Cast Resin Transformers Technical Guide GB

7/25/2019 Cast Resin Transformers Technical Guide GB

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T E C H N I C

A L G U I D E 0 8

DistributionCast resin transformers

ZDE08G/TA/GB



CONTENTS

1

CAST RESIN TRANSFORMERS TECHNICAL GUIDE

CONTENTS

General features 2

Description of EdM transformers 2

Certifications 3

Applications 4

Range 6

Constructional characteristics 8

Medium-voltage winding 9

Low-voltage winding 11

Environmental and climatic features and fire resistance 12

CLE system (certified low electromagnetic emission) 13

Transformer selection criteria 14

Technical information 36

Installation and maintenance 55



EdM boasts a long experience in the productionof dry transformers cast under vacuumin epoxy resin up to 36kV, offering themarket high-quality products with excellentperformance in many and varied applications.EdM is one of the most important producersof cast resin transformers in Europe,capable of guaranteeing, because of constantinvestment in research and development, astate-of-the art production process in both

productivity and product quality.

Correspondence to the specic Internationaland National Standards and conformityto classes C2, E2 and F1 mean that EdMtransformers can be used in many installationand environmental contexts. The absenceof inammable insulating liquids, the self-extinguishing materials exempt of toxic gasemissions, and the low noise levels representa safeguard for the environment and publichealth.

Description ofEDM transformers

2 RESIN TRANSFORMERS



ACCEPTANCE TESTS• Measurement of the

winding resistance IEC 60076-1

• Measurement of thetransformation ratio and checkof the polarity and connections IEC 60076-1

• Measurement of the short-circuitvoltage and the losses due to load IEC 60076-1

• Measurement of the no-load lossesand the no-load current IEC 60076-1

• Insulation testwith applied voltage IEC 60076-3

• Insulation testwith induced voltage IEC 60076-3

• Measurement of the partial discharges IEC 60076-11

TYPE TESTS• Atmospheric impulse test IEC 60076-3• Heating test IEC 60076-2 SPECIAL TESTS• Measurement of the noise level IEC 60076-10• Test of seal to short-circuit IEC 60076-11

Certications

IEC 60076-11 (2004):Dry-type power transformers;

IEC 60076Power transformers;

HD 538.1 S1 (1992)Dry-type transformers enclosed in resinwith insulation up to class 36KV;

STANDARDSThe safety and continuity of operation of thespecic users depend essentially on the reliabilityof the transformers installed.EdM cast resin transformers have beendesigned and manufactured according to theprovisions laid down by the main national andinternational standards.

TESTS AND INSPECTION

Before the cast resin transformers producedby EdM are supplied to the customer, theyare individually inspected and must pass theacceptance and, when necessary, type tests, ifthey are required in the order phase.At the end of the acceptance tests a specicinspection delivered with each transformer.

Both the ordering company and any nalcustomer can reserve the right to be present atthe inspections in the EdM test room and, on priornotication, can make inspection visits before andduring the manufacturing of the order.

3


GENERAL FEATURES



Applications

EdM cast resin transformers are used in a vastrange of applications and represent the mostreliable answer for distribution systems, powerproduction, rectication, traction and for specialneeds.

SERVICE SECTOR– Hospitals– Banks– Schools– Shopping and cultural centres

– Management centres

INFRASTRUCTURES– Airports– Military installations– Ports and off-shore installations

INDUSTRY IN GENERAL

DISTRIBUTION OF ELECTRICALPOWER:

– Air-conditioning systems– Continuity units– Railways, underground railways,

tramways and cable cars– Lifting and pumping systems

– Welding lines– Induction furnaces– Naval propulsion

CONVERSION ANDRECTIFICATION

– Wind parks– Photovoltaic systems– Cogeneration systems– Industrial applications

STEP-UP TRANSFORMERS FOR THEPRODUCTION OF POWER




Transformers for rectication and traction feature:

• very low total losses

• optimised design on the basis of the specic

harmonic load of the application

• small dimensions

• windings designed to optimise the temperaturerise of operation

• design resistant to network stresses

Transformers for wind and photovoltaic generatorsfeature:

• very low total losses

• reduced small height and width

• high resistance to atmospheric force

• design optimised for variable loads

• very silent operation

• pre-equipped for the mounting of surge arresters

• designed to t mechanically into the wind generator

TRANSFORMERS FOR RECTIFICATION AND TRACTION

TRANSFORMERS FOR WIND AND PHOTOVOLTAIC GENERATORS

TRANSFORMERS FOR MARINE APPLICATIONS

Transformers for marine applications feature:

• optimised design on the basis of the specicharmonic loads

• small dimensions and weight

• EdM’s experience in the specic sector

• the design’s adaptability to the installationdimensional conditions

• specic containment and cooling enclosure

5


GENERAL FEATURES



The EdM range of cast resin transformers is largeand can answer every market need, by proposingstandard products and special products on specicrequest.

Range

SUPPLY OF STANDARD PRODUCTS:

Distribution transformers– Rated power: 100 to 3150 kVA– Primary rated voltage: up to 36kV– Secondary rated voltage: up to 433V

SUPPLY OF SPECIAL PRODUCTS:

Special transformers– Rated power: up to 17000 kVA– Primary rated voltage: up to 36kV– Secondary rated voltage: on request

Please contact EdM for the special transformers.The company is able to offer all the necessaryassistance and technical competence in identifyingthe solution which will best satisfy the specicdesign features and needs.

P (KVA)

V2(kV)

V1(kV)




EdM standard cast resin transformers are classiedon the basis of losses by volume P0.Five categories of transformer are available:

CLE – CERTIFIED LOWELECTROMAGNETIC-EMISSIONS

R – REDUCED LOSSES

N – NORMAL LOSSES

D – DISTRIBUTIONS – STANDARD

EdM cast resin transformers are supplied:– in standard version

(without enclosure IP00)– with protective enclosure (degree of protection IP21, IP31 or IP23)

STANDARD EQUIPMENT– Bi-directional castors– Lifting eyebolts– Terminals for earth connection

ACCESSORIES ON REQUEST– Pt100 thermosensors with connection box– PTC thermistors

(as an alternative to the Pt100 thermosensors)– Electronic unit for thermal control, with inputs for

Pt100, without temperature display– Electronic unit for thermal control,

with inputs for Pt100 and temperature display– Forced ventilation systems to increase the

transformer power– MV terminations for plug-in connections

(Elastimold)– Transformer protective boxes– Earthing kit– Surge arrester kit

Contact EdM for further accessories or special

versions.

7


GENERAL FEATURES



Constructionalcharacteristics

EdM is distinguished by its high-quality production.Using state-of-the-art constructional techniquesand equipment and with constant attentionthroughout the production process and a rigorouscheck in the nal phase, guarantees quality for100% of the production.

MV windings in aluminium strip coils, castin resin under vacuum.

Core in three columns in magneticlamination with high-permeabilityoriented crystals, also available with lowlosses.

LV windings in aluminium plate/sheetand vacuum-cast impregnated insulationmaterial.

LV connections upwards (standard) ordownwards version (on request).

MV connections upwards (standard) ordownwards version (on request).

Rubber inserts attenuate the transmissionof vibrations between core and windingsand reduce to a minimum the operatingnoise generated by the transformer aswell as absorbing the thermal expansionof the components.

Sockets on the MV side to adapt theprimary voltage to the mains, which can

be set with transformer switched OFF.

Structure, armatures and carriage, madein strong painted sheet steel.

Carriage with bi-directional castors.

The epoxy resin insulation has a highashpoint and is self-extinguishing andmakes the transformer low maintenance. The operating temperature is checked byPt100 sensor or PTC in the LV windings.

Lifting eyebolts conform to the DIN-580

UNI-2947 standards with safety hookingat 4 points.

Optional pre-equipment for connectionof the LV connection to Zucchini busbartrunking system.

Class F insulating material, at 155°C,allowing for a temperature rise of 100°K.

The carriage allows safe movement andis pre-equipped for the mounting of an IPreinforced boxes.

5

7

8

6

1

2

3

10-14

9 -15

11 13 4 12

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15




Medium-voltagewinding

The medium-voltage winding, made by highlyautomated winding machines, is constructedwith the continuous disk technique and made inaluminium strip, interleaved with double insulation.This type of working produces uniformity of theinternal and external thickness of the resin andguarantees uniform resistance to the dielectricstresses to which the transformer will be subjectedin the inspection phase or during its operation at theplace of installation.

Modern electronicallycontrolled windingmachines

The pouring systemunder high vacuum.

The primary winding has sockets to adjust theprimary voltage equal to the value ± 2 x 2.5%, madewith brass bushes protruding from the resin, coppernuts and bolts and indelible numbering (not withadhesive labels).The thermal class of the insulating materials usedcorresponds to class F, with the temperature risesallowed by standard IEC 60076-11.

9


GENERAL FEATURES



Medium-voltagewinding

The tecnology used in making the MV windingsin strips, rather than in wire, puts less stress onthe insulation between the turns. In traditionalwindings, made with a circular-section conductor,each layer of the winding is made up of a numbern of turns side by side. In windings made with stripconductors, each layer is made up of just one turn.

If the voltage of a single turn of a winding isdenoted by us, in strip windings the voltagebetween turns belonging to two adjacent layers isalways us, while in traditional windings this voltageassumes the maximum value of (2n – 1) us, asshown in the diagram below.

Transformers with strip windings thus have agreater capacity of resistance to impulse voltagesand at industrial frequencies, as well as a lowerprobability of occurence of localised partialdischarges. Strip winding also has the advantageof drastically reducing the axial forces due toshort-circuit currents.

Winding made with wire conductors:the voltage increases with the number of turns.

Winding made with strip conductors:the voltage is divided uniformly.

Division of the voltage between the turns of the medium-voltage winding

1 2 3 4 5 6 7

2 3 4 5 6 7 8

U

1

2

3

4

5

6

7

8

➃

➄

➅

➆

➇

➃

➂

➁

➀

➅

➃

➄

➅

➂

➆

➂

➆

➁

➇

➁

➇

➀

U




The low-voltage winding, is made up of a singlealuminium strip, of the same mechanical heightas the MV electrical winding, with an interleavedsheet of insulating material which can be class F orclass H. The winding made in this way guaranteesa compactness which forms a single cylinderwhich resists any axial and radial forces which mayarise from a short-circuit.All the welds of the conductor strip with theoutput bars are made by butt welding in inert

atmosphere and under electronic control, so asto avoid any excess of material which could byrepeated stress affect or damage the insulationinterposed between output terminal and thefollowing turn.This winding is then impregnated with epoxyresin, by means of treatment under vacuum,to confer the necessary compactness andhomogeneity, as well as avoiding the absorptionof humidity during the transformer’s lifetime,wherever it may operate.This treatment allows to obtain the systemclassication at level F1 according to standards IEC60726 and IEC 60076-11.

Low-voltagewinding

TIG welding in controlledatmosphere for LVconnections.

LV winding system

11


GENERAL FEATURES



Standard IEC 60076-11 (HDL 464 S1 1988) uses analphanumeric code to identify the environmental,climatic and re behaviour classes of dry-typetransformers.

– environmental class (E0 – E1 – E2)

– climatic class (C1 – C2)

– re-behaviour class (F0 – F1)

Thanks to the use of a high-quality epoxy resin,all the EdM transformers reduce environmentalimpact to a minimum and conform to thefollowing classes:

– environmental class E2

– climatic class C2

– re-behaviour class F1

The thermal class of the insulating materials used corresponds to class F and the temperature rises arethose given in the specic standards for the transformer product.

ENVIRONMENTAL TESTS

E0No condensation on thetransformer, negligible pollution,installation in a clean and dryroom.

E1

Occasional condensation andlittle pollution.

E2The transformer is subject toconsistent condensation, tointense pollution, or to bothphenomena.

CLIMATIC TESTS

C1The transformer will not operateat temperatures lower than -5°C,but may be exposed to -25°Cduring transport and storage.

C2

The transformer can operate andbe transported and stored attemperatures down to -25°C.

FIRE RESISTANCE

F0The risk of re is not expectedand no measures are taken tolimit inammability.

F1 The transformer is subject to

the risk of re and reducedinammability is required. Fireon the transformer must beextinguished within laid-downlimits.

Environmental and climatic featuresand re resistance




CLE system (certied lowelectromagnetic emission)

The CLE system with low electromagneticemission conforms to DPCM 8/7/2003 and isapplied to substations and electrical cabinets inmedium and low voltage.The CLE (Certied Low Emission) transformationsystem consists in a range of special castresin transformers housed in enclosures,designed and constructed for use in workingenvironments where people are always present.The construction adopted for CLE transformation

systems in fact limit the electromagnetic emissionto values much lower than 10 microTesla (the EdMquality objective is 3 microTesla) in any direction,as required by DPCM 8/7/2003.Each CLE transformation system comes with aspecic electromagnetic emission measurementreport.Zucchini possesses a state-of-the-art anechoicchamber for testing, thus EdM’s CLE systemtransformers also come with a measurementreport of the noise subdivided by emission range.

Example of anelectromagnetic emission andnoise measurement report

13


GENERAL FEATURES



TRANSFORMERSELECTION CRITERIA




SECTION CONTENTS

16 Types of transformer

18 Choice of transformers

18 Technical comparison

19 Advantages of EDM cast resin transformers

21 Economic comparison

22 Energy saving transformers with reduced losses

24 Protection against temperature rises

26 Ventilation of the transformers

28 Protection against overloads

32 Protection against short-circuit

33 Protection against short-circuit with MV fuses

33 Protection against short-circuit with MV circuit breaker

34 Protection against overvoltages

35 The main vectorial groups of the transformers

15


CONTENTS



Dry-type transformers, with one or more enclosedwindings, are usually called cast resin transformers.These types, because of the developments madein constructional techniques, are more and morewidely used because of their reliability and becauseof their lower environmental impact with respectto oil transformers, because they reduce the risks

of re and spreading polluting substances in theenvironment.Medium-voltage windings, made with wire coilsor, even better, in insulated aluminium strips, areplaced in a mould into which the epoxy resin ispoured under vacuum, to avoid inclusions of gasin the insulations. The windings are then enclosedin a cylindrical enclosure, which is impermeable,mechanically strong and with a smooth surfacewhich impedes both the deposit of dust and theaction of polluting agents.Low-voltage windings are generally made in a singlealuminium sheet, as high as the coil, insulated bysuitable material and heat treatment.Cast resin transformers use class F 155°C insulatingmaterial, allowing for a maximum temperature riseof 100°K.

CAST RESIN TRANSFORMERS

Types oftransformer

Medium-voltage transformers are generally classied in threetypes depending on their construction. In the pages belowwe will often see comparisons between the features of castresin transformers and oil transformers.The three types of transformer are:

• Resin insulated dry-type transformers• Oil transformers• Air insulated transformers

EDM cast resin transformer




The windings of air transformers are insulatedby means of the wrapping of the windingsthemselves, the mounting of plastic partitions andthe respect of adequate insulation distances.These types limited use, because their specicconstructional characteristics make them verysensitive to humidity, to even limited pollution andto chemically aggressive substances. In fact theabsorption of humidity and the deposit of dustscan lower the dielectric coefcient of the insulatingmaterials used.

A careful commissioning procedure must thus befollowed, so as not to affect operation, such as thedrying of windings by means of heating elementsinstalled on the transformer.

AIR TRANSFORMERS

In oil transformers the windings are inserted insidea enclosure generally lled with mineral oil, whichhas the double function of guaranteeing adequateinsulation between the windings and the earthand dispersing the heat generated by the normaloperation of the transformer itself. The oil increasesin volume as the temperature of the surroundingsof the transformer itself rises. To compensate these

variations of volume some transformers have an“expansion vessel”, situated in the upper part,which compensates the variations of volume of theinsulating liquid. This tank communicates with theoutside by means of lters to remove the humiditywhich, if it accumulated, could impair the dielectricproperties of the oil with consequent problems forthe transformer itself.The liquid’s dielectric strength could be seriouslyaffected by the inefciency of the ltering system.For this reason the lters must be checkedregularly and replaced if necessary. Other types of

oil transformer instead do not have an expansionvessel and the liquid is contained in the leak-tight enclosure, where the windings are situated.In these types of transformer the variations ofvolume are compensated by a reservoir of dry airand nitrogen which acts as volume regulator. Theproblem with these transformers is that the seal ofthis air and nitrogen reservoir may deteriorate withtime.

OIL TRANSFORMERS

Oil transformer

Air transformer


17SELECTION CRITERIA



The transformer is an electric electromagneticinduction machine whose function is to transferelectrical power between two different voltagesystems at the same frequency. Transformers areavailable on the market in different constructionaltechnologies which have a considerable inuenceon the electrical properties and the elds ofapplication. To select the type of transformercorrectly one needs to know its different electricaland thermal properties and the resistance to

stresses due to faults or normal service of thetransformer itself. The transformer constructional

technology thus nally also determines theselection of the adequate protection. Anotherparameter to be borne in mind when selectingthe transformer is the type of operation for whichit is intended. For example, when used withlow loads or under a vacuum, oil transformersshould be selected; in the contrary case dry-typetransformers with low losses should be used.This selection is even more preferable when thetransformer will operate for long times at loads

more than 50% of the normal value.

Choice oftransformers

Properties Resin Oil Air

Inflammability YES NO YES

Self-extinguishing in the case of an electric fault YES NO YES

Need for anti-fire structures such as oil collection pit and anti-flame walls NO YES NO

Hygroscopicity of the insulation materials NO YES YES

Environmental pollution NO YES NO

Strip windings and good resistance to short-circuit YES NO NO

Stability of the heating element to short-circuit over the machine lifetime YES NO NO

Special commissioning procedures NO NO YES

Regular maintenance NO YES YES

Risks of environmental pollution because of leak of liquid NO YES NO

Deterioration of the dielectric properties because of the effect of time and environmental effects NO YES YES

Lack of sensitivity to humid, saline and tropical environments YES YES NO

Location at the centre of gravity of the load and reduction of system and management costs YES NO NO

Reliability when not maintained and when labour specialised in installation is not readilyavailable YES NO NO

Capacity of withstanding high instantaneous overloads of short duration thanks to the lowercurrent density and high thermal constant YES NO NO

Technicalcomparison




The constructional characteristics of cast resintransformers mean that they can be consideredfor most installations.Their main advantages with respect to oiltransformers can be expressed in three categories:

1. reduction of environmental impact

2. simplication of installation

3. exibility in use

1. reduction of environmental impact

• Greater safety (low risk of re) Because of the use of high-quality epoxy

resin, EdM cast resin transformers reduceenvironmental impact to a minimum andconform to the international environmentalstandards IEC 60076-11 (HDL 464 S1 1988).

EdM transformers are manufactured entirely withame-retardant and self-extinguishing materials.They therefore have reduced inammability

Advantages of EDMcast resin transformers

(self-extinguishing) and a minimum emissionof toxic gases and opaque smokes (F1 re-resistance classication); they can work in damp,dusty, saline or polluted environments (E2environmental test classication) and offer highresistance to thermal shocks (C2 climatic testclassication).

• No cooling fluids Because they have no cooling uids EdM cast

resin transformers do not present risks ofpollution and drastically reduce their contributionwhen there is a re, as compared withtransformers using insulating liquid.

• Recovery of materials at the end of life Cast resin transformers can be considered as

having the construction which most respectsthe environment, which is particularly importantwhen the machine which has come to the endof its working life must be disposed of. At theend of the disposal the resin is considered aninert material and the primary and secondarywindings can easily be recycled.

Semi-nished

Finished product

Raw materials

Separation

- Non-polluting recovery- Reduction of costs- Respect of the environment and

resources





3. exibility in use

• Greater overloading capacity As cast resin transformers use air cooling and

take longer to reach operation temperature,they can be more overloaded than insulatingliquid transformers and are thus particularlysuitable for supplying loads with frequent currentbreakaway starting current. The transformerscan be overloaded, as long as the temperature

rise on the windings does not remain above theallowable value for long periods of time. Thefeed unit can be temporarily increased by meansof the application of ventilation systems, to beused to tackle particular operating situations(temporary overloads or high room temperature)or to make available a temporary reserve ofpower when there is an emergency (e.g. when atransformer is out of service).

• Reduction of maintenance Cast resin transformers have lower maintenance

costs because they need only be inspectedregularly to check that there is no accumulationof dust and dirt. Oil transformers instead mustbe monitored to guarantee the level of insulatingliquid and to check that its dielectric propertieshave not changed (e.g. the dielectric strength ofmineral oils reduces considerably when there aresmall traces of humidity).

2. simplication of installation

• Reduction of the overall dimensions Cast resin transformers have lower overall

dimensions, about 16% by dimension and 10%by weight.

• Reduction of building laying works Cast resin transformers do not need the

expensive building work which is instead

required for oil transformers, such as collectionpits, extinguishing grids and re-resistantseparation barriers, to prevent the propagationof re and the spreading of insulating liquids.As EdM cast resin transformers are class F1 noseparation provision with re barrier is needed.

• Installation inside buildings Thanks to the reduction of expensive building

works, the greater safety (low re risk) and theabsence of cooling uids, cast resin transformerscan be installed inside buildings, even near to

rooms where people are present. The spaceoccupied and the installation costs can thus becontained.

Moreover transformers installed inside thebuilding can be closer to the loads, with theadvantage of saving in connection costs andreducing losses in the supply line.

Advantages of EDM cast resin transformers

In resin

In oil

0

1000

2000

3000

4000

5000

6000

0

500

1000

1500

2000

2500

Size [kVA]

Weight[kg]

In resin

In oil

0

1

2

3

4

5

6

7

8

9

0

500

1000

1500

2000

2500

Size [kVA]

m³

In resin

In oil

Transformer volume (L x H x D) Transformer weight




From the economic point of view a transformermust be chosen evaluating all the costs shownbelow:

• purchase cost• cost of installation• operating costs• maintenance costs• costs due to the disposal of materials

To check a transformer’s operating costs correctlyone must check the ratio between no-loadlosses (Po) and load losses (Pc). The rst areindependent of the load and are constant for thewhole time the transformer is connected to themains (generally 365 days a year), considering thefeed unit voltage and frequency as constant. Load

losses are instead proportional to the square ofthe current and are variable, as a function of theoscillations of the load itself.From the expenditure point of view often thechoice of a transformer is based exclusively on thepurchasing cost or initial cost (Ci). To evaluate thetrue cost of a transformer however, the operatingcost (Ce), or the cost of the electricity consumedby the transformer in its lifetime, should beconsidered as well. This is particularly important if

one considers the need for energy saving whichall businesses must face nowadays. See the “CRTAdvantages” section for the other parameters toconsider in the cost evaluation.

Economiccomparison

LOWER PURCHASE COST

LOWER INSTALLATION COST

LOWER OPERATING COST

LOWER MAINTENANCE COST

LOWER COSTS DUE TO THE DISPOSALOF MATERIALS

GREATER SAVINGS





One can observe the cost and energy savingproduced by the use of low-loss EdM transformerswith respect to a transformer with normal losses.

Transformer A: low-loss transformer (EdM).Transformer B: transformer with normal losses.

The technical selection of a transformer isnormally carried out with great care, while thecost analysis to determine the type of transformeris not always carried out in such a scienticmethod.EdM transformers, characterised by low losses,allow considerable energy saving with respect totraditional cast resin transformers.The results of a cost comparison between two castresin transformers evaluating the total cost

(CT = Ci + Ce), in relation to the values of thelosses, are given below.

Transformer comparison

Comparison data Transformer A Transformer B

An = Rated power 1000 kVA 1000 kVA

Insulation class 21 kV 24 kV

n = Transformer technical life 20 20

Po = No-load losses 1.8 kW 3.1 kW

Pcc = Losses at rated load 9.8 kW 9.8 kW

kWh cost = 0.19 € (for simplicity of treatment, the cost of power is considered constant throughout the 24 hours) i = 3% (annual capital interest).

Energy saving transformerswith reduced losses

0

-

l a

/ l n

0.2

hours

0.4

0.6

0.8

1.0

1.2

2 4 6 8 10 12 14 16 18 20 22 24

Load diagram over the working days of a small industrial factoryIa: current effectively absorbed by the transformerIn: transformer rated currentG (working days): 220




0

-

20,000.00

40,000.00

60,000.00

80,000.00

100,000.00

120,000.00

140,000.00

2

160,000.00

4 6

Transformer A Transformer B

8 10 12 14 16 18 20

c o s t e

Δ Ct = 28,679 Euros

Δ Ci = 3,850 Euros

The nal result is that transformer A is already cheaper after only two years. The Δ initial costof 3,850 Euros has been completely recovered

To conclude, the initial cost does not represent agood parameter for the choice of a transformer,but must be considered as an investment. In

fact, with the assumptions considered, the nalsaving is generally seven times greater thanwhat is invested as initial cost and the paybackperiod is just two years.

For a careful choice of transformer, on thewww.zucchinispa.it site there is a calculationprogram similar to that used in the example.

0

-

l a

/ l n

hours

0.2

0.4

0.6

0.8

1.0

1.2

2 4 6 8 10 12 14 16 18 20 22 24

Load diagram over the working days of a small industrial factoryG (working days): 145

Present cost

and at the end of the transformer lifetime there isa saving of more than 28,000 Euros.





During its normal operation a transformer hasno-load losses and load losses whichfundamentally translate into dispersed thermalenergy. This energy depends on the constructionof the transformer itself, its power and theinstallation conditions. It should be rememberedthat the energy dispersed thermally is proportionalto the transformer temperature minus the roomtemperature. At a given room temperature, thetransformer temperature depends mainly on the

load losses. As the load increases consequentlythe losses and the room temperature increasefavouring a more rapid degradation of theinsulations and thus a greater probability of failureof the dielectric. This situation could also occurwhen, with equal losses due to load, the roomtemperature and consequently the transformertemperature increase. The standards deneinsulation classes which indicate the maximumtemperatures which can be reached by thetransformers in their normal operation and whichmust not be exceeded.

Protection againsttemperature rise

Insulation classes

Class Transformers Average temperature rise limits, at rated current

Class B (130°C) oil 80 °K

Class F (155°C) resin 100 °K

Class H (180°C) dry-type 125 °K

PTC sensor to check the temperature




Temperature rises depend not only on the loadand the overcurrents which may be detected bythe protection devices, but also on environmentalfactors (inefciency of the cooling system, faulton the forced ventilation and increase of theroom temperature) which inuence the dispersalof heat produced by the transformer’s speciclosses. For this reason electronic temperaturemeasuring devices are normally provided. Theseare necessary to give the alarm or to trigger

transformer protection. The following temperaturesensors are available for EdM transformers: Pt100thermosensors and PTC thermistors.

Typical transformer alarm and release temperature values

Transformer type Room (°C) Alarm (°C) Release (°C)

Oil 40 105 118Resin 40 140 155

Air 40 165 180

• Pt100: supplies a signal proportional to thetemperature measured;

• PTC: supplies an ON/OFF signal depending onwhether the temperature measured is less ormore than the sensor’s threshold.

The sensors are positioned in the hot point of thewinding.Both the Pt100 and PTC signals must be processedby the temperature control unit, which does notform part of the standard equipment.

On request other accessories are available tocheck the temperature:• a separate temperature display, to be installed

on the control panel;• an output relay for alarm and release and control

of the fans.

Temperature rise limits for cast resin transformers

Part Insulating system temperature (°C) Maximum temperature rises (°C)

Windings:(temperature rise measured with the heatingelement variation method)

105 (A) 60

120 (E) 75

130 (B) 80

155 (F) 100

180 (H) 125

200 135

220 150

Core, metal parts and adjacent materials -In no case must the temperature reach values whichwould damage the core itself, other parts or adjacentmaterials





As mentioned before, during its service atransformer produces heat due to losses. Thisheat must be dissipated from the room where thetransformer is installed. For this purpose, one mustensure that there is adequate natural ventilationin the room. If not, forced ventilation must beinstalled.The CEI UNEL 21010 standards state that thetemperature of the installation room air must notexceed the following values:

20°C average annual30°C average daily40°C maximumThe system protecting against temperature risesmust be calibrated based on the maximum roomtemperature value of 40°C plus the maximumtemperature rise determined by the standards andby the delta K of the hot point where the sensorsare installed.

A good cooling system is obtained when the aircurrent enters from the bottom, crosses the roomwhere the transformer is installed and leavesfreely from the top in the opposite part (this ismandatory in many local standards). To evaluatethe effectiveness of the natural ventilation and

Ventilation ofthe transformers

consequently check the section of the ventilationopenings and the possible positioning heights,consider the following variables:

TL = total losses in kWΔT = temperature difference between air inlet and

outletQ = ow of air through the lower window in

m3/secH = distance in metres between the median

of the cabin and the median of the upperwindow (outlet window).

We denote the net area of the lower air inletwindow in m2 (excluding the grill) by S. AssumingΔT = 15°C, the formula to dimension the inletwindow is:

S = 0.185 x (TL √ H)(for different ΔT consult a specialist).

The outlet window (S’) must be about 15% largerthan the inlet window.If the air ow so calculated cannot be obtained,ventilation bars should be used.

S

QH min =160mm

S'

H




If the transformer room is small, or badlyventilated, use forced ventilation. This is alsonecessary when the average annual temperatureis higher than 20°C or when there are frequenttransformer overloads. To avoid affecting thenatural convection in the room an air extractormay be installed in the upper opening, possiblycontrolled by a thermostat.

USING PTC SENSORS

In three-phase transformers, the checkingsystem is made up of three sensors, one perphase, connected in series. The sensors are justresistances which send the release signal to arelay when the reaction temperature thresholdis exceeded. The sensor working conditionsare quickly reset when the temperature dropsbelow the threshold of 3°K. When there are twomonitoring systems, one gives the alarm signaland the other the release. The temperature valuesof the two systems deviate by 20°K. When theprotection relay is fed by the mains served by the

transformer, a delayed contact inhibits the alarmand release signals from when the transformer isput into service until the relay coil is powered.

1W 1V 1U

1 5

2W 2V 2U 2N 3

2

4

230Va.c.alarm/release

l

1 Temperature sensors2 Protection relay3 Alarm or release4 Delayed contact5 Transformer terminal board

H min =160mm

S'

H

S

CHECKING THE TEMPERATURE

The temperature may be checked using Pt100temperature sensors or thermometers. Analternative solution is to use PTC sensors,

which however has the disadvantage that thetemperature cannot be displayed.These systems are used to check the temperatureof the low-voltage windings. For transformersfor the supply of static current converters, thetemperature of the magnetic core should also bechecked.





Overload is the phenomenon which occurs whenthe value of current absorbed by the system ishigher than the rated value. The persistence ofan overload inevitably leads to exceeding theacceptable temperature rise limits speciedfor the transformer, with the consequent riskof deterioration of the insulating materials.Exceptionally, in certain abnormal serviceconditions, it may be acceptable to exceed theoverload and temperature rise thresholds, to

the detriment of the transformer’s expectedlifetime. This situation is sometimes preferableto an interruption of service (due to a temporarypower peak) which could cause considerablematerial and economic damage. In most cases theoverloads are transient and thus generally do notaffect the thermal equilibrium. The “acceptable”overload level is a function of the user’s need forservice continuity and the type of system itself.For insulating-liquid transformers the circulationof the cooling oil and the shape of the radiatorcontainment tanks allow the rapid restorationof the insulation and the reduction of partialdischarges, as well as allowing the transformer toreach its operating temperature quickly.

Protection againstoverloads

Overload capacity of an oil transformer

10Ir

5Ir

2Ir

Ir

5s 20s 2mn 10mn 1h 5h t

10s 1mn 5mn 20mn 2h

For cast resin transformers, the cooling componentis air and thus it takes longer to reach theoperating temperature. In these conditions castresin transformers may be more overloaded andthus may be used in systems with loads wherethere are frequent breakaway starting currents.This is true as long as the temperature rises onthe windings do not remain above the allowablevalues for too long. A partial solution of theproblem may be the use of radial fans afxed to

the cast resin transformers, allowing a temporarytransformer overload up to 150% of the ratedpower. It should however be remembered thatas the power increases the losses due to loadincrease. As they depend on the square of thecurrent they can reach up to 2.25 times the ratedvalue. Axial fans should only be used in special andtemporary cases to cool the windings or to havea sort of power reserve which may be used inemergency situations.

Example of radial fans for CRT




In public distribution, in the short term priorityis given to continuity of service. For this reasonoverloads do not generally lead to switchingthe transformer OFF. Again for the same reasongenerally low-voltage circuits are alwaysoverdimensioned and consequently an overloadof the transformer never corresponds to an

overload of the conductors. Attention shouldbe paid however when the overloads repeattoo frequently. In this situation the distributingorganisation should replace the transformer with amodel of greater power.

Airport

In an industrial installation, the overload can lastfor a short or long time. In these installations the

main distribution board equipped with protectivecircuit breakers against overload and short-circuit is always immediately downstream of thetransformers. Management of the overload isin fact delegated to the circuit breakers on thelow-voltage side which will detach the loads in anautomatic or controlled way.

Factory

OVERLOAD IN INDUSTRIAL DISTRIBUTION

In service installations, such as ofces and shoppingcentres, continuity of service is fundamental. Inthese types of application conditions of regularload which have starting regimes or similarbehaviour rarely occur.To guarantee maximum continuity of service evenwhen there are overloads it is essential that theloads considered non-priority are managed anddisconnected when needed by the transformer onthe Low-Voltage side.

Shopping centre

OVERLOAD IN PUBLIC DISTRIBUTION

OVERLOAD IN SERVICE DISTRIBUTION





PROTECTION AGAINST OVERLOADS BY MEANS OF CIRCUIT BREAKERS

For correct protection against overloads thecurrent values absorbed by the system must notexceed a threshold between 110 and 150% ofthe rated current. Protection against overloadmay be provided on both the Medium-Voltageside and the Low-Voltage side, depending on thetransformer power. For low-power transformers

the protection should be positioned on theLow-Voltage side, while for high-powertransformers the protection should be providedon the Medium-Voltage side. Protection againstoverloads on the MV side is provided using MVcircuit breakers associated with maximum-currentprotections in constant time or independent time.These circuit breakers also guarantee protectionagainst high fault currents. LV-side protectionis instead provided using LV circuit breakersinstalled in the main distribution board. Thesecircuit breakers have an inverse time curve whichprotects the transformer. For correct transformer

protection the circuit breaker is adjusted as a

function of the rated current of the transformerupstream. However, the selective chronometriccoordination of the circuit breaker with respectto other circuit breakers installed on the LV sideshould also be taken into account, as well as anyfaults which may occur at a distance from thetransformers, between the phases or between

one phase and the earth. In this case rememberthat the fault current is lower (about 2 – 3 timesthe transformer In). These types of faults must notbe underevaluated; even if they are slight, if theyare persistent, they could be extremely damagingfor the transformer. For suitable transformerprotection against these faults circuit breakerswith trips with the “thermal memory” functionshould be provided.

Legrand DMX circuit breaker

Protectionagainst overloads




PROTECTION AGAINST OVERLOADS BY MEANS OF MEASURING THE TEMPERATURE

As previously stated, overload, is fundamentallyassociated to a temperature rise which is the realcomponent to be kept under control, becauseits effects could lead to the rapid deteriorationof the insulation materials and to the failureof the transformer’s dielectric properties.Verifying the temperature is a determining factor

protection of the transformer itself. To check thetemperature therefore, cast resin transformersare generally equipped with thermoresistors, inturn connected to electronic control units, whichsignal or directly release the transformer when thedened thresholds are exceeded. EdM cast resintransformers have these thermoresistors installednear the parts which are most critical from thethermal point of view. For oil transformers insteadthe temperature measurement is managed usingthermostats. The dielectric liquid works like acooling uid for the windings and tends to levelthe transformer internal temperature. The use

of a thermostat as measurement device allowsmanaging more operation thresholds, which maybe used for example to activate the load transferor for forced cooling of the transformer.

Pt100 temperaturecontrol unit

Fan controlunit

Example of installation of a Pt100 temperature control unit





Protection against short-circuit

The reference standards dene that transformersmust be designed and manufactured to withstandthe thermal and mechanical effects due toexternal short-circuits without damage. Theimpedance of the low-voltage circuits is thedetermining factor for calculating the short-circuit currents which could be damaging, fromthe point of view of electro-mechanical stresses,for a transformer with a fault immediatelydownstream. A fault on the low-voltage side near

the transformer terminals causes a thermal stressand a mechanical stress on the transformer itselfwhich are functions of the values and duration ofthe fault. Transformers are designed to withstandshort-circuits between their terminals in the most

critical situation which corresponds to having aninnite fault source and short-circuit.It should be remembered however that repeatedfaults can have cumulative effects which couldcontribute to the rapid ageing of the insulationmaterial.To deal with this problem protection devicesshould be provided (fuses or automatic circuitbreakers) which can limit these effects and reducethe risks of damage to the transformer because of

thermal effects. For effective protection adequateprotection devices should be provided on boththe Low-Voltage side and the Medium-Voltageside (taking account of any necessary selectivecoordinations).

Selectivity between MV fuses and LV protection devices

t

Ir IMT

MV fault zone

MV/LV fault zone

MV fuse

LV fuse

LV circuit breaker




Because fuses are inexpensive and easy to usethey are widely used to protect distributiontransformers in public networks. While simplicityand price are denite advantages it is howevertrue that there are limits in the use of fuses. Theyare often used in conditions of low protectionwhere special requirements of selectivecoordination or continuity of service are notrequired. Fuses have a rated current value anda time/current melting property. MV fuses are

generally available in 2 versions: expulsion fusesand limitation fuses. The rst are generally usedin the air distribution system. The second aregenerally more widely used because of theircapacity of response to high currents within afew milliseconds. The high response speed is theparameter which offers the capacity of limitationof the fuse itself and which allows adequateprotection, even in the most serious conditions,reducing the risk of damage to the transformerand the associated circuits. The choice of the mostsuitable fuse for protection reasons is howeververy complex and must take account of variousfactors. An error in choosing the fuse could in fact

Protection against short-circuitwith MV fuses

Protection against short-circuitwith MV circuit breaker

To obtain more effective protection, withadjustment levels of the current thresholds andthe operating times and to obtain selectivity withrespect to the protections placed downstream ofthe transformer on the LV side, Medium Voltagecircuit breakers are more and more commonlyused. MV circuit breakers placed upstream of thetransformer have protection relays with thresholdswhich rarely correspond to the rated current ofthe transformer monitored. This means that theprotection curves move towards higher currentvalues, with a consequent increase of the level ofselectivity.

A protection circuit breaker dedicated to the MVtransformer must have the following properties:

• greater speed of operation of the MV protectiondevice immediately upstream;

• greatest possible speed for higher current valuesof the short-circuit current on the LV side;

lead to faulty service due to its melting, if it isunderdimensioned, or to lack of protection if it isoverdimensioned.

The criteria for correct choice of a fuse are:• the transformer service voltage;• the switch ON currents;• the transformer temporary overload level;• the time taken to remove the fault on the LV

side;

• the selectivity level with the LV protections.

• they must let the switch ON current pass;• they must guarantee monitoring of the overload

zone.

Example of an MV fuse

Example of an MV circuit breaker





Transformers may be affected by transient-induced overvoltages on the mains to whichthey are connected. These overvoltages, due todirect or indirect lightning strikes or to electricaloperation on machines installed on the LV side,can in turn give rise to stresses on the transformerdielectric which could cause its rapid ageing andconsequent failure in time, giving rise to faultson the transformer. The most critical conditionsnormally occur when voltage to the transformers

is cut by non-automatic circuit breakers whichinterrupt the currents. It should be rememberedthat the seriousness of an overvoltage depends onthe peak value and the speed variation voltage, asfactors which leads to an irregular distribution ofthe stresses in the windings. The risk of exposureto overvoltages is in the rst instance linked tothe place of installation and then to the followingfactors:

• type of MV distribution network and type of LVnetwork (above or under ground);

• whether there are any overvoltage limitationdevices (arresters or spark-gaps);

Protection againstovervoltages

• length and type of mains/transformerconnection;

• type of equipment connected and operationconditions;

• quality of the earth and cabin connections.

Faults caused by overvoltages concern theinsulation of the transformer and its componentsand may be divided into:

• faults between the turns of the same winding(most frequent case);• faults between windings;• faults between the stressed winding and a

touching conductor part (core or tank).

Spark-gaps and surge arresters (which performmuch better) may be used to efciently protecttransformers against overvoltages.

Example of a characteristic curve of a Zinc Oxide (ZnO) arrester for 20kVmains with “impulse” 125 kV insulation level.

I

5kA

10mA

15kV 75kV U




Internal windings may be connected in star,triangle or zigzag. Depending on the connectionmethod the system of induced voltages on thelow-voltage side is out of phase with respect tothe average voltage by angles which are multiplesof 30°. The winding connection method isidentied by 3 letters (upper case for the primaryand lower case for the secondary):

Y - star connection

D - triangle connectionZ - zigzag connection

Associated with these letters are identiednumbers which represent the phase shift, dividingit into 4 groups:

Group 0 – no phase shiftGroup 11 – 330°Group 6 – 180°Group 5 – 150°

The choice of the transformer switching ON unit isone of the important factors for determining theoperating regime as a function of the load. Theideal condition is when the load is balanced on allthe phases, but this condition is often impossible toobtain. For this reason one must know the phaseshift between primary and secondary phases. Thetable below shows the typical insertion diagrams.

The main vectorial groupsof the transformers

1W

1W

1W

1W

1W

1W

1U

1U

1U

1U 1U

1U

1U

1V

1V

1V

1V 1V

1V

1V

1W

1W

1W

1W

1W

1W

1U

1U

1U

1U

1U

1V

1V

1V

1V

1V

2W

2W

2W

2W

2W

2W

2W

2W

2W

2W

2W

2W

2U

2U

2U

2U

2U

2U

2U

2U

2U

2U

2U

2U

2V

2V

2V

2V

2V

2V

2V

2V

2V

2V

2V

2V

Dd0

1W1U 1V 1W1U 1V

1W1U 1V

1W1U 1V

1W1U 1V

1W1U 1V

1W1U 1V

2W2U 2V

2W2U 2V

2W2U 2V

2W2U 2V

2W2U 2V

2W2U 2V

2W2U 2V

1W1U 1V 2W2U 2V

1W1U 1V 2W2U 2V

1W1U 1V 2W2U 2V

1W1U 1V 2W2U 2V

1W1U 1V 2W2U 2V

Yy0

Dz0

Dy11

Yd11

Yz11

Dd6

Yy6

Dz6

Yz5

Yd5

Dy5

D y

n

Type of connection

Possibleaccessible starcentre

Primary windings

(upper case letter)

Secondary windings

(lower case letter)

Group

Angular phase shift inadvance

11

Ur

Ur

3

Ur, I3

Zig-Zag

Ir

Ir

Ur

Triangle

Ir

Ir

3

Ir

3

Ur

Ur

3

Star

Ir





TECHNICALINFORMATION




38 12 kV insulation class

42 17.5 kV insulation class



52 LV connection terminals

53 Boxes

54 Options

SECTION CONTENTS

37


CONTENTS



kVA Item Prim V Sec V Uk% Po (W) Pk(W) Io% Acoustic Acoustic Weight pressure (dB(A)) power (dB(A)) kV V 120° 75° Lp(A) Lw(A) kg 100 EB2RBCBA 10 400 4 320 2000 1760 1.8 40 51 550

EB2NBCBA 10 400 4 440 2000 1760 1.9 46 59 550 160 EC2RBCBA 10 400 4 440 2700 2380 1.6 43 54 700 EC2NBCBA 10 400 4 610 2700 2380 1.7 50 62 700

200 ED2RBCBA 10 400 4 540 3150 2770 1.4 45 56 800 ED2NBCBA 10 400 4 720 3150 2770 1.5 51 63 800 250 EE2RBCBA 10 400 4 600 3500 3080 1.1 46 57 950

EE2RACBA 10 400 6 580 3700 3260 1.1 46 57 910 EE2NBCBA 10 400 4 820 3500 3080 1.2 52 65 950 EE2NACBA 10 400 6 750 3700 3260 1.2 52 65 910

EE2DACBA 10 400 6 910 3800 3340 1.5 55 67 980 EE2SACBA 10 400 6 1050 3800 3340 1.9 58 70 1050 315 EF2RBCBA 10 400 4 730 4400 3870 1 47 59 1050

EF2RACBA 10 400 6 700 4600 4050 1 47 59 1000 EF2NBCBA 10 400 4 880 4400 3870 1.1 53 67 1050 EF2NACBA 10 400 6 850 4600 4050 1.1 53 67 1000

EF2DACBA 10 400 6 1050 4600 4050 1.4 56 69 1150 EF2SACBA 10 400 6 1320 4600 4050 1.8 59 72 1200 400 EG2RBCBA 10 400 4 880 4900 4360 0.9 48 60 1250

EG2RACBA 10 400 6 790 5400 4810 0.9 48 60 1200

EG2NBCBA 10 400 4 1150 4900 4360 1 53 68 1250 EG2NACBA 10 400 6 1000 5400 4810 1 53 68 1200

EG2DACBA 10 400 6 1320 5600 5000 1.3 57 70 1200 EG2SACBA 10 400 6 1630 5600 5000 1.7 60 73 1250 500 EH2RBCBA 10 400 4 1020 6500 5780 0.8 49 61 1450

EH2RACBA 10 400 6 920 6700 5960 0.8 49 61 1400 EH2NBCBA 10 400 4 1300 6500 5780 0.9 54 69 1450 EH2NACBA 10 400 6 1200 6700 5960 0.9 54 69 1400

EH2DACBA 10 400 6 1630 6700 5960 1.2 57 71 1400 EH2SACBA 10 400 6 1790 6700 5960 1.5 60 74 1500

TECHNICAL DATA FROM 100 TO 500 kVA

12 kV insulation class

Standards CEI 14-4 and 14-8 - IEC 60076-11 - CENELEC HD 538.1

Power (kVA) 100 - 3150

Frequency (Hz) 50

Primary Voltages (kV) 6 - 10 - 11 insulation class 12 kV BIL 60/75 kV

Secondary Voltages (V) 400 - 433 insulation class 1.1 kV

Adjustment, MV side ± 2 x 2.5%

Vectorial group Dyn11

Insulating system insulation class F / F

Temperature rise 100 / 100 K Class E2 - C2 - F1 Certified CESI No. 98/11 908

Tolerances According to CEI / IEC

Notes Different values of primary or secondary voltage available at extra cost Lp (A) = Value measured at a distance of one metre, according to standard CEI EN 60076-10




kVA Item Uk% A B C D ØR G H N Weight

(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (kg) 100 EB2RBCBA 4 1000 600 1100 520 125 270 330 690 550 EB2NBCBA 4 1000 600 1100 520 125 270 330 690 550 160 EC2RBCBA 4 1050 600 1140 520 125 270 330 710 700 EC2NBCBA 4 1050 600 1140 520 125 270 330 710 700 200 ED2RBCBA 4 1150 620 1190 520 125 270 330 710 800 ED2NBCBA 4 1150 620 1190 520 125 270 330 710 800 250 EE2RBCBA 4 1250 630 1270 520 125 270 330 820 950 EE2RACBA 6 1250 630 1220 520 125 270 330 800 910 EE2NBCBA 4 1250 630 1270 520 125 270 330 820 950 EE2NACBA 6 1250 630 1220 520 125 270 330 800 910 EE2DACBA 6 1250 640 1300 520 125 270 330 820 980 EE2SACBA 6 1250 640 1300 520 125 270 330 820 1050 315 EF2RBCBA 4 1200 750 1300 670 125 345 405 830 1050 EF2RACBA 6 1250 750 1250 670 125 345 405 800 1000 EF2NBCBA 4 1200 750 1300 670 125 345 405 830 1050 EF2NACBA 6 1250 750 1250 670 125 345 405 800 1000 EF2DACBA 6 1350 750 1370 670 125 345 405 840 1150 EF2SACBA 6 1350 750 1370 670 125 345 405 840 1200 400 EG2RBCBA 4 1250 750 1370 670 125 345 405 870 1250 EG2RACBA 6 1300 750 1320 670 125 345 405 850 1200

EG2NBCBA 4 1250 750 1370 670 125 345 405 870 1250 EG2NACBA 6 1300 750 1320 670 125 345 405 850 1200

EG2DACBA 6 1350 750 1430 670 125 345 405 920 1200 EG2SACBA 6 1350 750 1430 670 125 345 405 920 1250 500 EH2RBCBA 4 1250 750 1550 670 125 345 405 1010 1450 EH2RACBA 6 1300 750 1500 670 125 345 405 1000 1400 EH2NBCBA 4 1250 750 1550 670 125 345 405 1010 1450 EH2NACBA 6 1300 750 1500 670 125 345 405 1000 1400 EH2DACBA 6 1350 750 1540 670 125 345 405 1020 1400 EH2SACBA 6 1350 750 1540 670 125 345 405 1020 1500

DIMENSIONS AND WEIGHTS

Summary reference values.Use the construction drawingfor the design.

All the data given may bemodified without warningfor reasons of technicalproduction or productimprovement.

LV terminalsPage. 52

39


TECHNICAL INFORMATION



kVA Item Prim V Sec V Uk% Po (W) Pk(W) Io% Acoustic Acoustic Weight pressure (dB(A)) power (dB(A)) kV V 120° 75° Lp(A) Lw(A) kg 630 EI2RBCBA 10 400 4 1150 7300 6500 0.7 50 62 1650 EI2RACBA 10 400 6 1050 7600 6750 0.7 50 62 1600 EI2NBCBA 10 400 4 1500 7300 6500 0.8 55 70 1650 EI2NACBA 10 400 6 1450 7600 6750 0.8 55 70 1600 EI2DACBA 10 400 6 1790 7800 6940 1.2 58 72 1650 EI2SACBA 10 400 6 2100 7800 6940 1.4 61 75 1800 800 EJ2RACBA 10 400 6 1350 9400 8370 0.7 52 64 1950 EJ2NACBA 10 400 6 1750 9400 8370 0.8 57 71 1950 EJ2DACBA 10 400 6 2100 9400 8370 1.1 59 73 1900 EJ2SACBA 10 400 6 2470 9400 8370 1.3 62 76 2100 1000 EK2RACBA 10 400 6 1550 10000 8900 0.6 53 65 2300 EK2NACBA 10 400 6 2000 10000 8900 0.7 58 73 2300 EK2DACBA 10 400 6 2470 11000 9800 1 60 74 2300 EK2SACBA 10 400 6 2940 11000 9800 1.2 63 77 2500 1250 EL2RACBA 10 400 6 1900 12700 11300 0.5 55 67 2700 EL2NACBA 10 400 6 2300 12700 11300 0.6 59 74 2700 EL2DACBA 10 400 6 2940 13400 11800 1 61 75 2700 EL2SACBA 10 400 6 3520 13400 11800 1.1 64 78 2900 1600 EM2RACBA 10 400 6 2200 14000 12460 0.4 56 68 3300 EM2NACBA 10 400 6 2800 14000 12460 0.5 60 76 3300

EM2DACBA 10 400 6.5 3520 16400 14400 0.9 63 77 3400 EM2SACBA 10 400 6.5 3890 16400 14400 1 66 80 3750

2000 EN2RACBA 10 400 6 2800 18000 16200 0.4 58 70 4000 EN2NACBA 10 400 6 3300 18000 16200 0.5 61 79 4000 EN2DACBA 10 400 7 3890 19000 17100 0.9 65 80 4250 EN2SACBA 10 400 7 4830 19000 17100 0.9 68 83 4550 2500 EO2RACBA 10 400 6 3300 21000 18900 0.3 59 71 4800 EO2NACBA 10 400 6 4300 21000 18900 0.4 63 81 4800 EO2DACBA 10 400 7 5040 23000 20700 0.8 66 82 4900 EO2SACBA 10 400 7 5990 23000 20700 0.8 69 85 5250 3150 EP2RACBA 10 400 7 3950 26000 23400 0.3 62 74 5400 EP2NACBA 10 400 7 4600 26000 23400 0.4 65 83 5400




Power (kVA) 100 - 3150

Frequency (Hz) 50

Primary Voltages (kV) 6 - 10 - 11 insulation class 12 kV BIL 60/75 kV





Temperature rise 100 / 100 K

Class E2 - C2 - F1 Certified CESI No. 98/11 908 Tolerances According to CEI / IEC






(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (kg) 630 EI2RBCBA 4 1350 850 1600 670 150 395 455 1060 1650

EI2RACBA 6 1500 850 1590 670 150 395 455 1060 1600 EI2NBCBA 4 1350 850 1600 670 150 395 455 1060 1650 EI2NACBA 6 1500 850 1590 670 150 395 455 1060 1600 EI2DACBA 6 1500 850 1670 670 150 395 455 1110 1650 EI2SACBA 6 1500 850 1670 670 150 395 455 1110 1800 800 EJ2RACBA 6 1500 850 1740 670 150 395 455 1160 1950 EJ2NACBA 6 1500 850 1740 670 150 395 455 1160 1950 EJ2DACBA 6 1500 850 1780 670 150 395 455 1120 1900 EJ2SACBA 6 1500 850 1780 670 150 395 455 1120 2100 1000 EK2RACBA 6 1550 1000 1820 820 150 470 530 1270 2300 EK2NACBA 6 1550 1000 1820 820 150 470 530 1270 2300 EK2DACBA 6 1550 1000 1890 820 150 470 530 1280 2300 EK2SACBA 6 1550 1000 1890 820 150 470 530 1280 2500 1250 EL2RACBA 6 1550 1000 2000 820 150 470 530 1340 2700 EL2NACBA 6 1550 1000 2000 820 150 470 530 1340 2700 EL2DACBA 6 1550 1000 2030 820 150 470 530 1440 2700 EL2SACBA 6 1550 1000 2030 820 150 470 530 1440 2900 1600 EM2RACBA 6 1650 1000 2180 820 150 470 530 1460 3300 EM2NACBA 6 1650 1000 2180 820 150 470 530 1460 3300

EM2DACBA 6.5 1650 1000 2180 820 150 470 530 1560 3400 EM2SACBA 6.5 1650 1000 2180 820 150 470 530 1560 3750 2000 EN2RACBA 6 1800 1310 2260 1070 200 580 730 1570 4000 EN2NACBA 6 1800 1310 2260 1070 200 580 730 1570 4000 EN2DACBA 7 1900 1310 2220 1070 200 580 730 1580 4250 EN2SACBA 7 1900 1310 2220 1070 200 580 730 1580 4550 2500 EO2RACBA 6 2050 1310 2390 1070 200 580 730 1650 4800 EO2NACBA 6 2050 1310 2390 1070 200 580 730 1650 4800 EO2DACBA 7 2050 1310 2310 1070 200 580 730 1600 4900 EO2SACBA 7 2050 1310 2310 1070 200 580 730 1600 5250 3150 EP2RACBA 7 2150 1310 2400 1070 200 580 730 1670 5400 EP2NACBA 7 2150 1310 2400 1070 200 580 730 1670 5400





41





kVA Item Prim V Sec V Uk% Po (W) Pk(W) Io% Acoustic Acoustic Weight pressure (dB(A)) power (dB(A)) kV V 120° 75° Lp (A) Lw (A) kg 100 EB3RAFBA 15 400 6 380 2050 1800 1.9 40 51 560 EB3NAFBA 15 400 6 430 1900 1670 2 45 59 560 160 EC3RAFBA 15 400 6 480 2900 2550 1.6 43 54 750 EC3NAFBA 15 400 6 570 2800 2470 1.7 49 62 750 200 ED3RAFBA 15 400 6 570 3600 3170 1.4 45 56 800 ED3NAFBA 15 400 6 680 3600 3170 1.5 51 63 800 250 EE3RAFBA 15 400 6 670 3800 3340 1.2 46 57 950 EE3NAFBA 15 400 6 750 3650 3210 1.3 52 65 950 EE3DAFBA 15 400 6 910 3800 3340 1.5 55 67 980 EE3SAFBA 15 400 6 1050 3800 3340 1.9 58 70 1050 315 EF3RAFBA 15 400 6 790 4600 4050 1.1 47 59 1050 EF3NAFBA 15 400 6 880 4500 3970 1.2 54 67 1050 EF3DAFBA 15 400 6 1050 4600 4050 1.4 56 69 1150 EF3SAFBA 15 400 6 1320 4600 4050 1.8 59 72 1200 400 EG3RAFBA 15 400 6 920 5500 4890 1 48 60 1250 EG3NAFBA 15 400 6 1000 5200 4630 1.1 54 68 1250 EG3DAFBA 15 400 6 1320 5600 5000 1.3 57 70 1200 EG3SAFBA 15 400 6 1630 5600 5000 1.7 60 73 1250 500 EH3RAFBA 15 400 6 1170 6700 5960 0.9 49 61 1400 EH3NAFBA 15 400 6 1200 6700 5960 1 55 69 1400

EH3DAFBA 15 400 6 1630 6700 5960 1.2 57 71 1400 EH3SAFBA 15 400 6 1790 6700 5960 1.5 60 74 1500 630 EI3RAFBA 15 400 6 1360 7800 6940 0.9 50 62 1700 EI3NAFBA 15 400 6 1600 7800 6940 1 55 70 1700 EI3DAFBA 15 400 6 1790 7800 6940 1.2 58 72 1650 EI3SAFBA 15 400 6 2100 7800 6940 1.4 61 75 1800 800 EJ3RAFBA 15 400 6 1600 9400 8370 0.8 52 64 2000 EJ3NAFBA 15 400 6 1780 9300 8290 0.9 57 71 2000 EJ3DAFBA 15 400 6 2100 9400 8370 1.1 59 73 1900 EJ3SAFBA 15 400 6 2470 9400 8370 1.3 62 76 2100


17.5 kV insulation class


Power (kVA) 100 - 3150

Frequency (Hz) 50

Primary Voltages (kV) 12 - 13.2 - 15 insulation class 17.5 kV BIL 75/95 kV

Secondary Voltages (V) 400 - 410 - 420 insulation class 1.1 kV











(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (kg) 100 EB3RAFBA 6 1050 600 1090 520 125 270 330 710 560 EB3NAFBA 6 1050 600 1090 520 125 270 330 710 560 160 EC3RAFBA 6 1200 630 1210 520 125 270 330 720 750 EC3NAFBA 6 1200 630 1210 520 125 270 330 720 750 200 ED3RAFBA 6 1250 630 1230 520 125 270 330 730 800 ED3NAFBA 6 1250 630 1230 520 125 270 330 730 800 250 EE3RAFBA 6 1250 640 1240 520 125 270 330 740 950 EE3NAFBA 6 1250 640 1240 520 125 270 330 740 950 EE3DAFBA 6 1250 640 1300 520 125 270 330 820 980 EE3SAFBA 6 1250 640 1300 520 125 270 330 820 1050 315 EF3RAFBA 6 1250 750 1300 670 125 345 405 840 1050 EF3NAFBA 6 1250 750 1300 670 125 345 405 840 1050 EF3DAFBA 6 1350 750 1370 670 125 345 405 840 1150 EF3SAFBA 6 1350 750 1370 670 125 345 405 840 1200 400 EG3RAFBA 6 1350 750 1390 670 125 345 405 910 1250 EG3NAFBA 6 1350 750 1390 670 125 345 405 910 1250 EG3DAFBA 6 1350 750 1430 670 125 345 405 920 1200 EG3SAFBA 6 1350 750 1430 670 125 345 405 920 1250 500 EH3RAFBA 6 1350 750 1520 670 125 345 405 940 1400 EH3NAFBA 6 1350 750 1520 670 125 345 405 940 1400

EH3DAFBA 6 1350 750 1540 670 125 345 405 1020 1400 EH3SAFBA 6 1350 750 1540 670 125 345 405 1020 1500 630 EI3RAFBA 6 1500 850 1630 670 150 395 455 1070 1700 EI3NAFBA 6 1500 850 1630 670 150 395 455 1070 1700 EI3DAFBA 6 1500 850 1670 670 150 395 455 1110 1650 EI3SAFBA 6 1500 850 1670 670 150 395 455 1110 1800 800 EJ3RAFBA 6 1500 850 1780 670 150 395 455 1170 2000 EJ3NAFBA 6 1500 850 1780 670 150 395 455 1170 2000 EJ3DAFBA 6 1500 850 1780 670 150 395 455 1120 1900 EJ3SAFBA 6 1500 850 1780 670 150 395 455 1120 2100





43





kVA Item Prim V Sec V Uk% Po (W) Pk(W) Io% Acoustic Acoustic Weight pressure (dB(A)) power (dB(A)) kV V 120° 75° Lp (A) Lw (A) kg 1000 EK3RAFBA 15 400 6 1890 11000 9800 0.7 53 65 2300 EK3NAFBA 15 400 6 2000 10800 9630 0.8 58 73 2300 EK3DAFBA 15 400 6 2470 11000 9800 1 60 74 2300 EK3SAFBA 15 400 6 2940 11000 9800 1.2 63 77 2500 1250 EL3RAFBA 15 400 6 2100 13000 11600 0.6 55 67 2750 EL3NAFBA 15 400 6 2350 12600 11250 0.7 59 74 2750 EL3DAFBA 15 400 6 2940 13400 11800 1 61 75 2700 EL3SAFBA 15 400 6 3520 13400 11800 1.1 64 78 2900 1600 EM3RAFBA 15 400 6 2420 16000 14240 0.5 56 68 3300 EM3NAFBA 15 400 6 2750 15500 13800 0.6 60 76 3300 EM3DAFBA 15 400 6.5 3520 16400 14400 0.9 63 77 3400 EM3SAFBA 15 400 6.5 3890 16400 14400 1 66 80 3750 2000 EN3RAFBA 15 400 6 2920 19000 17100 0.5 58 70 4000 EN3NAFBA 15 400 6 3350 18500 16650 0.6 61 79 4000 EN3DAFBA 15 400 7 3890 19000 17100 0.9 65 80 4250 EN3SAFBA 15 400 7 4830 19000 17100 0.9 68 83 4550 2500 EO3RAFBA 15 400 6 3650 23000 20700 0.4 59 71 4950 EO3NAFBA 15 400 6 4300 21800 19620 0.5 63 81 4950 EO3DAFBA 15 400 7 5040 23000 20700 0.8 66 82 4900 EO3SAFBA 15 400 7 5990 23000 20700 0.8 69 85 5250

3150 EP3RAFBA 15 400 7 3950 27000 24300 0.3 62 74 5750 EP3NAFBA 15 400 7 4700 26000 23400 0.4 66 83 5750


17.5 kV insulation class


Power (kVA) 100 - 3150

Frequency (Hz) 50

Primary Voltages (kV) 12 - 13.2 - 15 insulation class 17.5 kV BIL 75/95 kV












(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (kg) 1000 EK3RAFBA 6 1550 1000 1870 820 150 470 530 1290 2300 EK3NAFBA 6 1550 1000 1870 820 150 470 530 1290 2300 EK3DAFBA 6 1550 1000 1890 820 150 470 530 1280 2300 EK3SAFBA 6 1550 1000 1890 820 150 470 530 1280 2500 1250 EL3RAFBA 6 1550 1000 2010 820 150 470 530 1350 2750 EL3NAFBA 6 1550 1000 2010 820 150 470 530 1350 2750 EL3DAFBA 6 1550 1000 2030 820 150 470 530 1440 2700 EL3SAFBA 6 1550 1000 2030 820 150 470 530 1440 2900 1600 EM3RAFBA 6 1650 1000 2190 820 150 470 530 1470 3300 EM3NAFBA 6 1650 1000 2190 820 150 470 530 1470 3300 EM3DAFBA 6.5 1650 1000 2180 820 150 470 530 1560 3400 EM3SAFBA 6.5 1650 1000 2180 820 150 470 530 1560 3750 2000 EN3RAFBA 6 1800 1310 2250 1070 200 580 730 1580 4000 EN3NAFBA 6 1800 1310 2250 1070 200 580 730 1580 4000 EN3DAFBA 7 1900 1310 2220 1070 200 580 730 1580 4250 EN3SAFBA 7 1900 1310 2220 1070 200 580 730 1580 4550 2500 EO3RAFBA 6 1950 1310 2320 1070 200 580 730 1600 4950 EO3NAFBA 6 1950 1310 2320 1070 200 580 730 1600 4950 EO3DAFBA 7 2050 1310 2310 1070 200 580 730 1600 4900 EO3SAFBA 7 2050 1310 2310 1070 200 580 730 1600 5250

3150 EP3RAFBA 7 2150 1310 2350 1070 200 580 730 1610 5750 EP3NAFBA 7 2150 1310 2350 1070 200 580 730 1610 5750





45





kVA Item Prim V Sec V Uk% Po (W) Pk(W) Io% Acoustic Acoustic Weight pressure (dB(A)) power (dB(A)) kV V 120° 75° Lp (A) Lw (A) kg 100 EB4RBGBA 20 400 4 400 1750 1540 2 40 51 630 EB4RAGBA 20 400 6 360 2050 1800 2 40 51 570 EB4NBGBA 20 400 4 540 1750 1540 2.1 46 59 630 EB4NAGBA 20 400 6 480 2000 1760 2.1 46 59 570 160 EC4RBGBA 20 400 4 580 2500 2200 1.7 43 54 900 EC4RAGBA 20 400 6 480 2900 2550 1.7 43 54 800 EC4NBGBA 20 400 4 790 2500 2200 1.8 50 62 900 EC4NAGBA 20 400 6 650 2800 2470 1.8 50 62 800 200 ED4RBGBA 20 400 4 680 2900 2550 1.5 45 56 1030 ED4RAGBA 20 400 6 550 3600 3170 1.5 45 56 900 ED4NBGBA 20 400 4 900 2900 2550 1.7 51 63 1030 ED4NAGBA 20 400 6 800 3600 3170 1.7 51 63 900 250 EE4RBGBA 20 400 4 840 3450 3040 1.3 46 57 1150 EE4RAGBA 20 400 6 650 3800 3340 1.3 46 57 1000 EE4NBGBA 20 400 4 1000 3450 3040 1.5 53 65 1150 EE4NAGBA 20 400 6 850 3700 3260 1.5 53 65 1000 EE4DAGBA 20 400 6 1050 3800 3340 1.5 55 67 1050 EE4SAGBA 20 400 6 1210 3800 3340 1.9 58 70 1150 315 EF4RBGBA 20 400 4 970 4500 3970 1.2 47 59 1350 EF4RAGBA 20 400 6 750 4600 4050 1.2 47 59 1200

EF4NBGBA 20 400 4 1150 4500 3970 1.4 55 67 1350 EF4NAGBA 20 400 6 950 4500 3970 1.4 55 67 1200 EF4DAGBA 20 400 6 1210 4600 4050 1.4 56 69 1200 EF4SAGBA 20 400 6 1470 4600 4050 1.8 59 72 1250 400 EG4RBGBA 20 400 4 1160 4900 4360 1.1 48 60 1500 EG4RAGBA 20 400 6 940 5500 4890 1.1 48 60 1350 EG4NBGBA 20 400 4 1360 4900 4360 1.3 55 68 1500 EG4NAGBA 20 400 6 1150 5400 4810 1.3 55 68 1350 EG4DAGBA 20 400 6 1470 5600 5000 1.3 57 70 1350 EG4SAGBA 20 400 6 1740 5600 5000 1.7 60 73 1450




Power (kVA) 100 - 3150

Frequency (Hz) 50

Primary Voltages (kV) 20 - 23 insulation class 24 kV BIL 95/125 kV












(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (kg)

100 EB4RBGBA 4 1200 600 1160 520 125 270 330 730 630 EB4RAGBA 6 1050 600 1110 520 125 270 330 710 570 EB4NBGBA 4 1200 600 1160 520 125 270 330 730 630 EB4NAGBA 6 1050 600 1110 520 125 270 330 710 570 160 EC4RBGBA 4 1250 640 1260 520 125 270 330 740 900 EC4RAGBA 6 1250 640 1240 520 125 270 330 730 800 EC4NBGBA 4 1250 640 1260 520 125 270 330 740 900 EC4NAGBA 6 1250 640 1240 520 125 270 330 730 800 200 ED4RBGBA 4 1350 640 1320 520 125 270 330 750 1030 ED4RAGBA 6 1250 640 1250 520 125 270 330 740 900 ED4NBGBA 4 1350 640 1320 520 125 270 330 750 1030 ED4NAGBA 6 1250 640 1250 520 125 270 330 740 900 250 EE4RBGBA 4 1350 640 1360 520 125 270 330 830 1150 EE4RAGBA 6 1350 640 1260 520 125 270 330 750 1000 EE4NBGBA 4 1350 640 1360 520 125 270 330 830 1150 EE4NAGBA 6 1350 640 1260 520 125 270 330 750 1000 EE4DAGBA 6 1350 640 1360 520 125 270 330 850 1050 EE4SAGBA 6 1350 640 1360 520 125 270 330 850 1150 315 EF4RBGBA 4 1350 750 1450 670 125 345 405 880 1350 EF4RAGBA 6 1350 750 1350 670 125 345 405 860 1200

EF4NBGBA 4 1350 750 1450 670 125 345 405 880 1350 EF4NAGBA 6 1350 750 1350 670 125 345 405 860 1200 EF4DAGBA 6 1350 750 1410 670 125 345 405 860 1200 EF4SAGBA 6 1350 750 1410 670 125 345 405 860 1250 400 EG4RBGBA 4 1450 750 1530 670 125 345 405 900 1500 EG4RAGBA 6 1500 750 1440 670 125 345 405 880 1350 EG4NBGBA 4 1450 750 1530 670 125 345 405 900 1500 EG4NAGBA 6 1500 750 1440 670 125 345 405 880 1350 EG4DAGBA 6 1500 750 1510 670 125 345 405 1020 1350 EG4SAGBA 6 1500 750 1510 670 125 345 405 1020 1450





47








Power (kVA) 100 - 3150

Frequency (Hz) 50

Primary Voltages (kV) 20 - 23 insulation class 24 kV BIL 95/125 kV








kVA Item Prim V Sec V Uk% Po (W) Pk(W) Io% Acoustic Acoustic Weight pressure (dB(A)) power (dB(A)) kV V 120° 75° Lp (A) Lw (A) kg 500 EH4RBGBA 20 400 4 1370 6400 5700 1.1 49 61 1640 EH4RAGBA 20 400 6 1050 6700 5960 1.1 49 61 1500 EH4NBGBA 20 400 4 1580 6400 5700 1.2 56 69 1640 EH4NAGBA 20 400 6 1350 6700 5960 1.2 56 69 1500 EH4DAGBA 20 400 6 1740 6700 5960 1.2 57 71 1550 EH4SAGBA 20 400 6 2000 6700 5960 1.5 60 74 1650 630 EI4RBGBA 20 400 4 1600 6900 6150 1 50 62 2000

EI4RAGBA 20 400 6 1250 7800 6940 1 50 62 1800 EI4NBGBA 20 400 4 1950 6900 6150 1.1 56 70 2000 EI4NAGBA 20 400 6 1740 7800 6940 1.1 56 70 1800 EI4DAGBA 20 400 6 2000 7800 6940 1.2 58 72 1800 EI4SAGBA 20 400 6 2420 7800 6940 1.4 61 75 1950 800 EJ4RAGBA 20 400 6 1450 9400 8370 0.9 52 64 2100 EJ4NAGBA 20 400 6 1950 9300 8290 1 58 71 2100 EJ4DAGBA 20 400 6 2310 9400 8370 1.1 59 73 2150 EJ4SAGBA 20 400 6 2730 9400 8370 1.3 62 76 2350 1000 EK4RAGBA 20 400 6 1800 11000 9800 0.8 53 65 2500 EK4NAGBA 20 400 6 2310 10800 9630 0.9 59 73 2500 EK4DAGBA 20 400 6 2790 11000 9800 1 60 74 2550 EK4SAGBA 20 400 6 3260 11000 9800 1.2 63 77 2800 1250 EL4RAGBA 20 400 6 2100 13000 11600 0.7 55 67 2900

EL4NAGBA 20 400 6 2730 12800 11430 0.8 60 74 2900 EL4DAGBA 20 400 6 3260 13400 11800 1 61 75 3000 EL4SAGBA 20 400 6 3730 13400 11800 1.1 64 78 3250 1600 EM4RAGBA 20 400 6 2400 16000 14240 0.6 56 68 3550 EM4NAGBA 20 400 6 3100 15500 13800 0.7 61 76 3550 EM4DAGBA 20 400 6.5 3730 16400 14400 0.9 63 77 3600 EM4SAGBA 20 400 6.5 4410 16400 14400 1.1 66 80 3950 2000 EN4RAGBA 20 400 6 2900 19000 17100 0.5 58 70 4300 EN4NAGBA 20 400 6 3800 18600 16740 0.6 62 79 4300 EN4DAGBA 20 400 7 4570 19000 17100 0.9 65 80 4500 EN4SAGBA 20 400 7 5360 19000 17100 0.9 68 83 4900 2500 EO4RAGBA 20 400 6 3800 23000 20700 0.4 59 71 5250 EO4NAGBA 20 400 6 4800 22000 19800 0.5 64 81 5250 EO4DAGBA 20 400 7 5880 23000 20700 0.8 66 82 5200 EO4SAGBA 20 400 7 6620 23000 20700 0.8 69 85 5650 3150 EP4RAGBA 20 400 7 4500 26000 23400 0.4 62 74 6250 EP4NAGBA 20 400 7 5360 26000 23400 0.5 67 83 6250









(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (kg) 500 EH4RBGBA 4 1450 750 1610 670 125 345 405 980 1640 EH4RAGBA 6 1500 750 1560 670 125 345 405 960 1500 EH4NBGBA 4 1450 750 1610 670 125 345 405 980 1640 EH4NAGBA 6 1500 750 1560 670 125 345 405 960 1500 EH4DAGBA 6 1500 750 1570 670 125 345 405 960 1550 EH4SAGBA 6 1500 750 1570 670 125 345 405 960 1650 630 EI4RBGBA 4 1500 850 1690 670 150 395 455 1100 2000

EI4RAGBA 6 1500 850 1650 670 150 395 455 1080 1800 EI4NBGBA 4 1500 850 1690 670 150 395 455 1100 2000 EI4NAGBA 6 1500 850 1650 670 150 395 455 1080 1800 EI4DAGBA 6 1500 850 1700 670 150 395 455 1090 1800 EI4SAGBA 6 1500 850 1700 670 150 395 455 1090 1950 800 EJ4RAGBA 6 1550 850 1810 670 150 395 455 1200 2100 EJ4NAGBA 6 1550 850 1810 670 150 395 455 1200 2100 EJ4DAGBA 6 1550 850 1850 670 150 395 455 1300 2150 EJ4SAGBA 6 1550 850 1850 670 150 395 455 1300 2350 1000 EK4RAGBA 6 1650 1000 1890 820 150 470 530 1310 2500 EK4NAGBA 6 1650 1000 1890 820 150 470 530 1310 2500 EK4DAGBA 6 1650 1000 1930 820 150 470 530 1300 2550 EK4SAGBA 6 1650 1000 1930 820 150 470 530 1300 2800 1250 EL4RAGBA 6 1650 1000 2030 820 150 470 530 1370 2900

EL4NAGBA 6 1650 1000 2030 820 150 470 530 1370 2900 EL4DAGBA 6 1650 1000 2070 820 150 470 530 1460 3000 EL4SAGBA 6 1650 1000 2070 820 150 470 530 1460 3250 1600 EM4RAGBA 6 1750 1000 2200 820 150 470 530 1480 3550 EM4NAGBA 6 1750 1000 2200 820 150 470 530 1480 3550 EM4DAGBA 6.5 1800 1000 2250 820 150 470 530 1590 3600 EM4SAGBA 6.5 1800 1000 2250 820 150 470 530 1590 3950 2000 EN4RAGBA 6 1900 1310 2270 1070 200 580 730 1590 4300 EN4NAGBA 6 1900 1310 2270 1070 200 580 730 1590 4300 EN4DAGBA 7 1900 1310 2270 1070 200 580 730 1590 4500 EN4SAGBA 7 1900 1310 2270 1070 200 580 730 1590 4900 2500 EO4RAGBA 6 1950 1310 2350 1070 200 580 730 1610 5250 EO4NAGBA 6 1950 1310 2350 1070 200 580 730 1610 5250 EO4DAGBA 7 2050 1310 2310 1070 200 580 730 1600 5200 EO4SAGBA 7 2050 1310 2310 1070 200 580 730 1600 5650 3150 EP4RAGBA 7 2250 1310 2400 1070 200 580 730 1670 6250 EP4NAGBA 7 2250 1310 2400 1070 200 580 730 1670 6250

49





TECHNICAL DATA FROM 250 TO 3000 KVA


kVA Item Prim V Sec V Uk% Po (W) Pk(W) Io% Acoustic Acoustic Weight pressure (dB(A)) power (dB(A)) kV V 120° 75° Lp (A) Lw (A) kg 250 EE5NAIBA 25 400 6 1320 3600 3180 1.5 55 68 1380 315 EF5NAIBA 25 400 6 1450 4800 4250 1.4 56 69 1500 400 EG5NAIBA 25 400 6 1600 5800 5100 1.3 57 70 1700 500 EH5NAIBA 25 400 6 1800 7200 6350 1.2 58 71 1900 630 EI5NAIBA 25 400 6 2100 7600 6750 1 59 73 2250 800 EJ5NAIBA 25 400 6 2580 9400 8370 0.9 60 74 2700 1000 EK5NAIBA 25 400 7 2800 10500 9280 0.8 61 75 3100 1250 EL5NAIBA 25 400 8 3000 14000 12350 0.7 62 76 3400 1600 EM5NAIBA 25 400 8 3600 16500 14600 0.6 64 77 4050 2000 EN5NAIBA 25 400 8 4600 18000 16200 0.5 65 79 4900 2500 EO5NAIBA 25 400 8 5780 22000 19800 0.5 67 80 6000 3000 EP5NAIBA 25 400 8 6620 25500 22500 0.4 68 82 7000


Power (kVA) 250 - 3000

Frequency (Hz) 50

Primary Voltages (kV) 25 - 33 insulation class 36 kV BIL 170 kV


Adjustment, MV side ± 2 x 2.5% 33 kV: +2/-3 x 1.5 kV (36 - 34.5 - 33 - 31.5 - 30 - 28.5 kV)











(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (kg) 250 EE5NAIBA 6 1600 830 1430 670 125 345 485 880 1380 315 EF5NAIBA 6 1600 830 1480 670 125 345 485 900 1500 400 EG5NAIBA 6 1650 880 1600 670 150 395 485 1030 1700 500 EH5NAIBA 6 1650 890 1700 670 150 395 495 1110 1900 630 EI5NAIBA 6 1750 900 1800 670 150 395 515 1180 2250 800 EJ5NAIBA 6 1750 910 1920 670 150 395 505 1250 2700 1000 EK5NAIBA 7 1900 1000 2030 820 150 470 530 1350 3100 1250 EL5NAIBA 8 1900 1000 2180 820 150 470 530 1480 3400 1600 EM5NAIBA 8 1950 1020 2300 820 150 470 550 1500 4050 2000 EN5NAIBA 8 2050 1310 2320 1070 200 580 730 1520 4900 2500 EO5NAIBA 8 2250 1310 2430 1070 200 580 730 1640 6000 3000 EP5NAIBA 8 2350 1310 2550 1070 200 580 730 1820 7000




51





LV connectionterminals

DIMENSIONAL TERMINALS

LV connection terminals are made in aluminium. Special CUPAL interfacing plates(item 030013) are available to connect copper wires, at extra cost.

Drawing Range Thickness Width No. of holes Ø holes kVA mm mm mmA 100 4 40 1 13 160 4 40 1 13

B 200 5 50 1 15 400 5 50 1 15

C 500 6 60 2 13 630 6 60 2 13 800 8 60 2 13

D 1000 8 80 4 13

E 1250 8 100 4 15

F 1600 10 120 4 18 2000 12 120 4 18 2500 16 120 4 18 3150 20 120 4 18

All the data given can be modified without warning for reasons of technicalproduction or product improvement.

40

2 0

A= =

Ø13

50

2

5

B = =

Ø15

32

3 2

C = =

2xØ13

1 4

60

40

4 0

D = =

4xØ13

2 0

80

50

5 0

E= =

4xØ15

2 5

100

60

6 0

F = =

4xØ18

3 0

120





Boxes

KVA Item A B C S Weight Degree of protection (mm) (mm) (mm) (mm) (kg) Walls Base

100 230316 1600 900 1470 500 120 IP21 IP20 230353 1600 900 1470 500 120 IP31 IP20

230288 1600 900 1470 500 120 IP23 IP20

160 230316 1600 900 1470 500 120 IP21 IP20

230353 1600 900 1470 500 120 IP31 IP20

230288 1600 900 1470 500 120 IP23 IP20

200 230316 1600 900 1470 500 120 IP21 IP20

230353 1600 900 1470 500 120 IP31 IP20

230288 1600 900 1470 500 120 IP23 IP20

250 230211 1700 950 1580 405 140 IP21 IP20

230263 1700 950 1580 405 140 IP31 IP20

230273 1700 950 1580 405 140 IP23 IP20

315 230211 1700 950 1580 405 140 IP21 IP20

230263 1700 950 1580 405 140 IP31 IP20

230273 1700 950 1580 405 140 IP23 IP20

400 230212 1800 1000 1680 405 160 IP21 IP20

230234 1800 1000 1680 405 160 IP31 IP20

230215 1800 1000 1680 405 160 IP23 IP20

500 230212 1800 1000 1680 405 160 IP21 IP20

230234 1800 1000 1680 405 160 IP31 IP20

230215 1800 1000 1680 405 160 IP23 IP20

630 230204 1900 1050 1950 575 180 IP21 IP20

230222 1900 1050 1950 575 180 IP31 IP20

230277 1900 1050 1950 575 180 IP23 IP20

800 230204 1900 1050 1950 575 180 IP21 IP20

230222 1900 1050 1950 575 180 IP31 IP20

230277 1900 1050 1950 575 180 IP23 IP20

1000 230213 2050 1100 2200 600 210 IP21 IP20 230223 2050 1100 2200 600 210 IP31 IP20

230221 2050 1100 2200 600 210 IP23 IP20

1250 230213 2050 1100 2200 600 210 IP21 IP20

230223 2050 1100 2200 600 210 IP31 IP20

230221 2050 1100 2200 600 210 IP23 IP20

1600 230214 2300 1310 2500 730 280 IP21 IP20

230249 2300 1310 2500 730 280 IP31 IP20

230267 2300 1310 2500 730 280 IP23 IP20

2000 230214 2300 1310 2500 730 280 IP21 IP20

230249 2300 1310 2500 730 280 IP31 IP20

230267 2300 1310 2500 730 280 IP23 IP20

2500 230287 2500 1310 2700 730 300 IP21 IP20

230371 2500 1310 2700 730 300 IP31 IP20

230309 2500 1310 2700 730 300 IP23 IP20

3150 230287 2500 1310 2700 730 300 IP21 IP20

230371 2500 1310 2700 730 300 IP31 IP20

230309 2500 1310 2700 730 300 IP23 IP20

Degree of protection: IP21-IP31-IP23

Class 12-17.5-24 kV

For Class 36 kV boxes dimensions and weight on request

All the data given can be modified without warning for reasons of technicalproduction or product improvement.

A

C

S

B

Colour RAL 7032AREL door lock on the box item 230076

53





TEMPERATURE MEASUREMENT SENSORS

Options

Type Range Item Qty Temperature threshold Notes kVA °C

Pt100 up to 2000 200073 3 - 3 sensors mounted on the LV windings and wired in the box

Pt100 from 2500 200074 3 - 3 sensors mounted on the LV windings and wired in the box

Pt100 up to 2000 200137 4 - 3 sensors mounted on the LV windings plus a sensor mounted on thecore and wired in the box

Pt100 from 2500 200138 4 - 3 sensors mounted on the LV windings plus a sensor mounted on thecore and wired in the box

PTC - CB0012 6 130 - 140 3 pairs of PTC sensors on the LV windings for alarm and release.

Wired in the box

PTC - CB0240 6 110 - 120 3 pairs of PTC sensors on the LV windings for alarm and release.Wired in the box

The sensors are supplied mounted on the transformer and wired to a die-castaluminium IP 55 junction box.

VENTILATION BARS

Ventilation bars allow a temporary increase of the rated power (at ratedoperation conditions). Supplied mounted on the transformer.

Range Item Power Notes kVA increase % 100 - 250 CB02443 + 30

315 - 800 CB02453 + 301000 - 1250 CB02463 + 301600 - 2500 CB01413 + 20

3150 CB01411 + 15 a temporary increase in rated 100 - 250 CB02444 + 40 conditions 315 - 800 CB02454 + 40

1000 - 1250 CB02464 + 401600 - 2500 CB01414 + 30

3150 CB01412 + 20

FAN CONTROL UNIT

The unit is supplied non-mounted.

Type Item Notes VRT200 220035 To control the ventilation bars

TEMPERATURE CONTROL UNIT

The unit is supplied non-mounted.

Type Item Notes

T154 220002 Unit for 4 Pt100 sensors MT200 220023 Unit for 4 Pt100 sensors T119 DIN 220010 Unit for 6 PTC sensors.

Set up for mounting on DIN railT 119 22004 Unit for 6 Pt100 sensors

RUBBER BUFFERS

Range kVA Item Notes100 - 1600 170019 4 buffers supplied for mounting under

the transformer casters 2000 - 3150 170020 4 buffers supplied for mounting under the transformer casters

NON-MAGNETIC THERMOMETER

Item Description 250662 Thermometer without support bracket,

initial installation or for replacement 258005 Thermometer support bracket (always necessary)

KIT OF SURGE ARRESTERS MOUNTED ON THE TRANSFORMER

Voltage Vn kV Item10 130054D 15 130055D

20 130056D

All the data given can be modified without warning for reasons of technicalproduction or product improvement.For details on the functions of all optional components, see pages 24 to 35.




SECTION CONTENTS

56 Safety indications

57 Reference standards and rating plate

58 Transport, reception and storage

60 Installation

68 Commissioning

70 Maintenance

71 Technical glossary

INSTALLATION ANDMAINTENANCE

55


CONTENTS



The epoxy cast resin transformer is an electricaldevice.It must be installed, protected and used respectingthe international and national standards in force.

• Read these user instructions carefully beforelifting or moving the transformer or putting itinto service.

• All work operations must take place voltagefree.

• Do not switch the transformer ON before theearth connection has been made.

• Do not access the transformer area, or removeprotective parts without having switched thetransformer OFF.

Safetyindications

For all information or requests for spare partscontact the Customer Service, just giving the serialnumber. Telephone +39 30.2017100 or send ane-mail to:[email protected].

AFTER-SALES SERVICE

Lifting eyebolts

Connection for earth

MV windings

Carriage with casters

MV adjustment base

MV terminals

Magnetic core

Rating plate

Centralisation box

LV terminals




Reference standardsand rating plate

REFERENCE STANDARDS

IEC 60076-11 – Power transformers – Part. 11: Dry– type.IEC 60076-1 – Power transformers – Part. 1:General Amendment 1 (1999).IEC 60076-2 – Power transformers – Part. 2:Temperature rise.EC 60076-3 – Power transformers – Part. 3:Insulation levels, dielectric test and externalclearances in air.

IEC 60076-5 – Power transformers – Part. 5: Ability

RATING PLATE

Conditions for correct transformer operation

Observe the indications in these user instructions;Use the transformer in correspondence with the

data given on the plate;Connect the parts to be earthed by means of theterminals;

Protect against chemical agents, atmosphericcontamination and solar irradiation and against

vegetation or animals which could inuencenormal operating conditions;Protect against mechanical damage duringinstallation or in normal operating conditions.

to withstand short circuit.IEC 60076-10 – Power transformers – Part. 10:Determination of sound levels.IEC 60085 – Thermal evaluations and classicationsof electrical insulations.IEC 60270 – High-voltage techniques – Partialdischarge measurement.IEC 60529 – Degree of protection provided byenclosures (IP code).

IEC 60905:1987 – Loading guide for dry-typepower transformers.

57


INSTALLATION AND MAINTENANCE



During transport, the transformers must besuitably fastened, using the holes provided in theupper transformer armature.

On arrival at the destination, examine thetransformer carefully to make sure that it has notbeen damaged during transport (LV busbars orMV connections, broken insulators, scratches onthe MV windings, presence of humidity or dirt,protection enclosure damaged, presence of foreignbodies, etc.).

Transport,reception and storage

Warning: Do not stand underneath the suspended loads Warning: the transformer can tilt over

LIFTING

Make a note of any non-conformity found on the delivery note and informthe transporter or EdM via fax or recommended letter within 3 workingdays of receiving the transformer.




MOVEMENT

Whether the transformer has its protectiveenclosure or not, it must be moved by means ofthe carriage or the lower armatures, specicallyusing the holes in it.

DO NOT move the transformer by pushing directlyon the resin coils.

The casters are provided for positioning in the

transformer room. For movement over longerdistances, use adapted transport methods.

STORAGE

If the transformer is not installed immediately,it is good practice to protect it from water, dust,humidity and sunlight.

Usually the transformer is supplied with aprotective PVC covering which should not beremoved if it is to be stored.

The room temperature of the locale should not beless than -25°C.

Movement can be in two directions, depending on the wheel mounting.

59





EdM cast resin transformers are suitable in theirstandard version for installation indoors, in a cleandry room, with no possibility of entry of water,protected against direct solar radiation, with thefollowing temperatures in the standard version:maximum: +40°C, daily average: +35°C if used for24 h.Only if requested, and in specic environmentalconditions, can they be installed outdoors with the

Installation

transformers protected by an box, sheltered fromdirect sunlight and water, with a minimum degreeof protection IP 21.During installation, adhere to the Standards in effectfor the prevention of accidents at work.When there is, or may be, a special danger becauseof the presence of explosive or inammableatmospheres, refer to the provisions of the specicapplicable National Directives.

EXAMPLES OF INSTALLATION

The following shows some examples ofconnection from both below and above.

Installation in an enclosure




There are certain indications which must berespected:1. In standard version: installation indoors, in a

clean dry room, protected against direct solarradiation, with no possibility of entry of water.

To protect transformers against outsideinuences and people against risks of directcontact, a series of standard boxes is available,with different degrees of protection IP21-IP31-IP23, depending on installation requirements.

2. Altitude above sea level not greater than1000m (for higher altitudes, contact EdM).

3. Ambient air temperatures in the room, whenthe transformer is working (for higher valuescontact EdM):

• Minimum T: – 25°C • Maximum T: + 40°C4. In standard version the transformers are

dimensioned in accordance with theEN 60076-11 Standards for the followingambient air temperatures:

• 40°C at any time • 30°C as monthly average in the hottest month • 20°C as annual average

Examples of correct installation of cast resin transformers

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The blocking and/or tightening of the electricalconnections and mechanical fastenings must beperformed in accordance with the values given inthe table.

TORQUES OF ELECTRICAL CONNECTIONS AND MECHANICAL FASTENINGS

POSITIONING

The cast resin transformer does not guaranteesafe insulation against contact.

The enclosed windings must not be touched whenthe machine is live.

For this reason it must be installed inside an boxes,a fence or a room which is only accessible throughdoors with locks which can only be opened whenthe transformer is not live.

Inside the cabin the machine must be sopositioned that the minimum insulation distancesfrom the wall are respected. These distancesdepend on the transformer insulation class givenon the rating plate.

Electrical connections[Nm]

Mechanicalconnections

Screw/Bolt Steel Brass [Nm] (mm)

M 6 10-15 5-10 20 10

M 8 30-40 10-15 35 13

M 10 50-60 20-30 45 17

M 12 60-70 40-50 60 19

M 14 90-100 60-70 100 22

M 16 120-130 80-90 170 24

M 18 - - 240 27

M 20 - - 330 30

M 22 - - 450 32

M 24 - - 600 36

kV A (mm) B (mm) C (mm)

≤ 12 ≥ 125 ≥ 60 (*)

≤ 17.5 ≥ 170 ≥ 80 (*)

≤ 24 ≥ 225 ≥ 120 (*)

≤ 36 ≥ 320 ≥ 200 (*)

(*) if the adjustment terminals are:• on the MV connection side: C = B• on the LV connection side: C = A

Installation




The cooling surfaces must be ventilated by thecirculating air; this implies correct and suitableopenings for the passage of air (about 3.5 to 4 m3 of fresh air per minute for every kW of losses).Whenever the circulation of air is insufcient thetransformer will be subjected to incorrect heating,which in the most serious cases will cause thethermal protection to operate.

VENTILATION

“For transformers without casters, the base mustbe sufciently elevated from the ground to allowthe entry of cooling air from below.Whenever the geometry of the room doesnot allow an adequate exchange of air, an airextraction or circulation system must be installedto ensure suitable transformer cooling”.

OVERVOLTAGES

If the transformer is subjected to overvoltages(atmospheric or manoeuvres) it should beprotected by using a suitable surge arrester,calibrated according to the operating voltage.

COLD AIR

HOT AIR

Surge arresters for CRT

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The ZUCCHINI SCP busbar trunking system andEdM cast resin transformers, have been designedin perfect synergy for a direct connection. Theversions shown below represent just a few of thestandardised solutions.

To connect the medium-voltage cables tothe transformer correctly, the recommendedminimum distances must be respected (12 cmminimum) to avoid triggering discharges due toionisation or partial discharges. For more detailssee the “Installation and maintenance” sectionbelow.

Transformer400 V

currentlk 6%

Busbars

kVA Insulationclass Family Connection

component

(kVA) (kV) (A) (kA)

630

12, 17.5,24, 36

910 15.2 SCP 1000 A AI 60281012 P

800 1155 19.5 SCP 1250 A AI 60281014 P

1000 1443 24.1 SCP 1600 A AI 60281016 P

1250 1804 30.1 SCP 2000 A AI 60281017 P

1600 2310 38.5 SCP 2500 A AI 60391014 P

2000 2887 48.2 SCP 3200 A AI 60391016 P

2500 3608 60.2 SCP 4000 A AI 60391017 P

Transformer400 V

currentlk 6%

Busbars

kVA Insulationclass Family Connection

component

(kVA) (kV) (A) (kA)

630

12, 17.5,24, 36

910 15.2 SCP 1000 A Cu 60281011 P

800 1155 19.5 SCP 1250 A Cu 60281013 P1000 1443 24.1 SCP 1600 A Cu 60281015 P

1250 1804 30.1 SCP 2000 A Cu 60281016 P

1600 2310 38.5 SCP 2500 A Cu 60281018 P

2000 2887 48.2 SCP 3200 A Cu 60391015 P

2500 3608 60.2 SCP 4000 A Cu 60391016 P

Installation

Example of combination between EDM transformers and ZUCCHINI busbar ducts




The LV terminals are placed in the upper part ofthe transformer and are normally in aluminium.The cable connection must be made with tinnedcopper terminals, connecting one or two cablesper hole, as shown in the gure.

LV-SIDE CONNECTIONS

When connecting LV terminals with untreatedcopper busbars, special intermediate Cupal platesare supplied on request.

The MV terminals are integrated into the windingitself and are usually made with brass pins.The terminals positioned at the two ends of thewinding, allow:

• to facilitate the connection to the incoming MVcables from either the top or the bottom;

• the connection of the phases of the transformerto the MV mains;

• to avoid galvanic couples between the variousmaterials which might exist in the connection.

The brass bolts must not be replaced with bolts ofanother material. Such a modication could alter

the quality of the connection.

MV-SIDE CONNECTIONS

Cupal

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Installation without protective enclosure (IP00)

The MV and LV cables must always be solidlyanchored to avoid mechanical stress on theinsulators.

Installation




Every EdM transformer is equipped as standardwith Pt100 sensors.On request other temperature sensors can beused, such as PTC sensor (according to DIN44082).

TEMPERATURE CONTROL SYSTEM

If the transformer has a temperature monitoringunit, the recommended calibrations are:

Recommended calibration

Class Alarm (°C) Release (°C)

Class H 140 155

Class F 130 140

Class B 110 120

1 2 3 4 5 6 7 8 9 1 0

1 1

1 2

2u

P T C 1

3 0 ° C

P T C 1

4 0 ° C

P T C 1

3 0 ° C

P T C 1

4 0 ° C

P T C 1

3 0 ° C

P T C 1

4 0 ° C

2v 2w

PTC (130 - 140) °C

Spare

1 5

3 7

6 5

8 7

6 2

8 4

Control and command units for Pt100 or for PTCsensors are supplied on request.Wiring diagrams, number of contacts and theirfunction and terminal numbering can be found onthe specic unit user instructions.

Terminal board wiring diagrams

1

X1

Spare

2u 2v

Pt100

2w

1 2 3 4 5 6 7 8 9 1 0

1 1

1 2

2 3 4 5 6 7 8 9

1 2 3

1 2 3

4 5 6 7 8 9

4 5 6 7 8 9

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Commissioning

Earth conductor ≥ 16mm2, in accordance with Stan-dard IEC 11-1 chapter 9.

TRANSFORMER-EARTH CONNECTION

Before commissioning the transformer, make thefollowing checks:

1. Make sure that the windings have not movedand that the compression bolts are wellpositioned on the anchoring blocks.

2 Check the connections between the MV cablesand their isolators, the LV cables or busbars andthe transformer output plate.

3. Make sure that the earth connections and theauxiliary circuit connections are correct and well

tightened.

CONNECTIONS

If the transformer has remained unused for a longperiod, give it a general cleaning.Clean away any deposits of dust, dirt or

condensation from the MV/LV windings with avacuum cleaner, to avoid dispersing the depositson the remaining parts of the transformer.

CLEANING




The voltage tolerances of the electricity supplycompany can be compensated by changes onthe adjustment taps (movement of the plates) tokeep the voltage to the LV terminals constant.As standard, the transformers are supplied withvoltage taps -5%, -2.5%, 0%, +2.5% and +5%.The connection schema for the adjustments, fortransformers with one or two primary voltages isshown on the rating plates.

The plates must be moved on all 3 MV columns.The plates must have the same position on all theadjustment bases, to avoid circulation currentswhich would irreversibly damage the transformer.

TAPS FOR VOLTAGE ADJUSTMENT

After performing a general system check andmaking sure that no objects have been left onthe transformer, the MV-side feed unit circuitbreaker can be closed and the load applied to theLow-Voltage winding by closing the LV-side circuitbreaker.

COMMISSIONING

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Generally, in normal operating conditions, EdMcast resin transformers requires little specicmaintenance. Standard maintenance checks arelisted below.

Maintenance

Indicative table of the main maintenance and checking operations

Pos. Check to be carried out Frequency of the check Tool to use Result to obtain

1Operation of Pt100/PTCthermosensors

Annual and/or when needed Tester Electrical continuity

2Unit Monthly and/or after exceptional

events- Check operation as in the user

instructions

3Cleaning of dust, deposits of dirt andany foreign bodies on the windings

Weekly and/or if there are anyshutdowns

Dry low-pressure compressed airmax 3 bar and dry cloths

No occlusions/dirt in the MV and LVwinding cooling channels

4Condensation deposited on thewindings

After a transformer halt Furnace and/or heating method inshort circuit

Drying at about 80°C

5Nuts and bolts of the star/triangleconnections and MV/LV terminals

Annual and/or when needed Torque wrench Torque see table section 4.4

6

Check insulation of the windings,between themselves and to theearth

After a transformer halt Megaohmeter (Megger type) withvoltage greater than 1000V

LV and earth: min 5 MOhmMV and earth: min 20 MOhmMV and LV: min 20 MOhmWith smaller values, contact EdM

7Check centring of MV/LV windings onthe magnetic core

After exceptional events (accidentalimpact, short-circuit)

Meter Geometric centring of the windings

8Check suspension block adjustmentplates

Monthly and/or after exceptionalevents

Torque wrench Torque from 20 to 40 Nm

Guide to identication of problems and troubleshooting

Pos. Problem found Possible cause Procedures to follow

1Overheating Irregular distribution of the load Check the symmetry of the currents, changing the division

2Overheating High room temperature Make sure that the cabinet or protection enclosure ventilation openings are

not blocked.Reset the air circulation

3Overheating localised in the core Eddy currents in the core due to tie

rod breaking or insulation defectIsolate the central tie-rods on the end plate armatures, with insulating tubesand washers

4Overheating localised in the core Too high feed unit voltage Check the position of the change voltage plates, adapting them so that the

value of the voltage on the secondary under volume is less than or the sameas the rating plate value (on the + or ++)

5Noise Too high feed unit voltage

6Noise Rigid connections/fastenings with

any busbar ducts, or with the floorReplace the rigid connections with flexible connections and/or insert antivi-bration supports under the sliding rollers

7

Operation of the temperature sen-sors. Alarm/release

Defective unit or sensor Replace the defective component

Absorption of current at the/over therating plate limits

Reduce the load until the rated current is reached or install the forcedventilation kit

Cooling air which does not circulateregularly

See “Position” and “Ventilation”

Imperfect sensor electrical contact Check, clean and tighten all the contacts in the sensor measurement chain




Technicalglossary

The transformer rated properties to be taken intoaccount for a correct selection are:

Rated voltage of a winding (Vn) is the voltageapplied or induced in the no-load operation of thetransformer between the winding line terminals.

Short-circuit voltage (Vcc), is the voltage to beapplied between the winding line terminals so

that the rated current circulates between themwhen the terminals of the other winding are inshort-circuit. This voltage may be divided into aresistive component and an inductive component.This voltage value allows calculation of the short-circuit current at the secondary terminals if theimpedance upstream is neglected, according tothe formula:Icc = 100 In/Vcc.

The transformer impedance is also calculated withthis magnitude. It is necessary to calculate thisshort-circuit current in the Low-Voltage distributionsystem according to the formula:Z =Vcc % Vn/100 In

The transformer short-circuit currents are afunction of the transformer power and arestandardised on the values 4% and 6%.

No-load current (I0), is the magnetic circuitmagnetisation current which is established in awinding when this is supplied at rated voltage andfrequency (the other winding is open circuit). Thiscurrent value is expressed in % of the transformer

rated current. The magnetic circuit is made up ofinsulated laminations.

Switching on current, is the pick-up current peakwhich occurs when the transformer is powered. Itsinitial value can be even 8 – 10 times the windingrated current. The pick-up current of a transformermust be known to determine the calibrations forthe associated protection devices.

Noise, is caused by magnetostriction of themagnetic circuit laminations. The noise is a

function of the transformer magnetic workinduction and the quality of the laminations.The noise level can be expressed in terms ofAcoustical pressure Lp (A), or Acoustical powerLw (A) and is independent of the load.

No-load losses (Po), represent the active powerabsorbed by the transformer when the ratedvoltage is applied at the rated frequency to one ofthe two windings and with the other winding withopen circuit. No-load losses, also called iron losses,are independent of the load and are equivalent tothe sum of the losses caused by the hysterisis andthe eddy currents (Foucault).

Load losses (Pcc), are the losses due to the ohmiccurrents on the main circuits, to the additionallosses in the windings and to the losses on themetallic masses. These losses are proportional tothe square of the load current and are expressedat a standardised reference current of 75°Cfor oil transformers and 120°C for cast resintransformers.

Rated power (Sn) is the conventional value of

the power assigned to a winding which, togetherwith the rated voltage, allows us to determine therated current.

ELECTRICAL PROPERTIES OF THE TRANSFORMERS

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Item Tolerance

1a) Total lossesb) Partial losses(no load or load)

+ 10% of the total losses+ 15% of each of the partial losses, on condition that the tolerance for thetotal losses is not exceeded

2

No-load transformation ratio on the main tap for a first specific pair ofwindings

The lesser of the two following values:a) ± 0.5% of the declared ratiob) ±1/10 of the real percentage short-circuit impedance on the main tap

Transformation ratio on other taps for the same pair of windingsMust be agreed, however it must be not less than the lower of the twovalues in a) and b) above

3

Short-circuit impedance for:• transformers with separate windings and with two windings, or• a rst specied pair of separate windings in a transformer with several

windings

a) Main tap When the impedance value is ≥10% ± 7.5% of the declared valueWhen the impedance value is < 10% ± 10% of the declared value

b) Any other tap of the pair of windings When the impedance value is ≥10% ± 10% of the declared valueWhen the impedance value is < 10% ± 15% of the declared value

4

Short-circuit impedance for:• a pair of auto-connected windings• a second specied pair of separate windings in a transformer with several

windings

a) Main tap b) Any other tap of the pair

± 10% of the declared value± 15% of the declared value

• More pairs of windings To be agreed however ≥15%

5 No-load current 5. No-load current + 30% of the declared value

Note:(1) In the case of transformers with several windings, the tolerances on the losses must be understood as for each pair of windings unless the guarantee does not

specify that they refer to a defined combination of the load.(2) For certain autotransformers and booster transformers the smallness of their impedance guarantees wider tolerances. Transformers with wide adjustment

ranges, particularly if the range is asymmetric, may also require special consideration. On the other hand, for example, when a transformer must be associated to already existing units, it may be justified to specify and agree smaller tolerances on

the impedances. The problems with special tolerances must be highlighted when the invitation to tender is given and the reviewed tolerances agreed betweenmanufacturer and purchaser.

(3) The expression “declared value” must be understood as value declared by the manufacturer.

Technicalglossary




Zucchini SpAVia Conicchio, 3425136 Brescia - Italy

Tel. +39 030 2017100Fax +39 030 [email protected]

Cast Resin Transformers Technical Guide GB

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