ECODIAL 336

2SIS - Franck MEGRET - June 2004 - English

1. INTRODUCTION

Ecodial 3.36 :

98 SE, Win 2000, XP

Included : Contactors , Circuit breakers (Telemecanique), Thermal relays, Soft starters, Variable speed drives,

Capacitors

Calculation method : CENELEC (R0064-003) Installation rules : IEC364, C15-100 (ed. 2003), BS7671


Calculation standards define the formulas that should be used to calculate short circuit currents. IEC909 : method to calculate three phase short circuit currents in electrical

installations

IEC363 : method to calculate three phase short circuit currents on ships

What is a calculation GUIDE ? A simplified method that is usually accepted internationnally under certain conditions.

CENELEC guide R064-003 (as known as NFC15-500): method for calculating ALL short circuit currents (min, max, earth fault, single phase, three phase, …), voltage drops, cable short circuit withstand…

Guide often ignores transient phenomenon such as motor contribution, asymetric component, inrush when calculation short circuit levels.

Simplification is acceptable as product standards (IEC60947-2) take these transient phenomenons into consideration, for example :

- an 50kA Icu breaker must be able to ‘make’ at least 110kA peak Icm

What are ‘calculation standards’ ?IEC909, IEC363, ...


What are ‘installation rules’ ?IEC60364, NFC 15-100, BS7671, CP5, AS3008, ...

Installation rules address all the issues relative to safety : overload protection minimum cable sizes protection against direct and indirect contact short circuit protection

These rules are usually all based on the same inital document (IEC60364), onto which each country usually includes local requirements (temperature, safety, cable derating…).


What is Ecodial ?

Ecodial is a low voltage network calculation tool.

It can calculate simple ‘arborescent’ type networks no loops/ring feed systems

Ecodial calculates cable cross section based on

- upstream protection setting, maximum allowable voltage drop, protection against indirect contact,

short circuit currents according to :

- type of short circuit, polarity of circuit and earthing method sets protection devices based on

- short circuit currents, expected loads, …


What Ecodial is not :

Ecodial is not : A medium voltage design tool A tool that can be used lightly : professional engineers must check verify and certify

these results The solution to all the possible design problems that one may encounter.

Ecodial cannot solve all the layouts Several studies could be made... Simplified network should be drawn...


General characteristics

- definition of the global parameters (voltage, earthing, …)

Drawing- definition of the network layout

Definition of circuit characteristics

- definition of the terminal load, and all the cable lengths

Power sum

- calculation of the required power, and current in the distribution circuits

Calculation- sizing of cable, calculation of short circuit currents, choice of equipment, …

Results

- printout of the input / output used for the calculations

The main steps of an Ecodial study


Un Ph-Ph (400V) : sets the LV network voltage. This value corresponds to a phase-phase voltage

Earthing arrangement (TNS) : sets the earthing arrangement at the transformer. This value can only be changed in a network after an LV/LV transformer, or from TNC to TNS.

Cascading (YES) : authorises Ecodial to use reinforced breaking capacity to choose downstream breakers. This can help reduce the cost of an installation.

Discrimination (standard) : displays the discrimination results and chooses breakers giving better discrimination results.

Smax (240mm²) : sets the maximum cable CSA that Ecodial can use when sizing cables (multiple cables in parallel can always be used though)

General characteristicsCalculation / General characteristics


CSA N / CSA Ph (1) : sets the minimum ratio between phase and neutral conductors. This is used to allow half neutrals (1/2) or require full neutrals (1).

Tolerance (5%) : Ecodial calculates the theoretical Phase CSA. Tolerance can be included to allow the choice of cable slightly smaller than the theoretical value.

Standard (IEC947-2) : Allows the user to choose a default product standard (IEC947-2 or IEC898) according to which the breaking capacity of the circuit breakers are given. If the standard is set to IEC898, Ecodial automatically chooses IEC947-2 if no IEC898 are available

Target power factor (0.96) : this is the value Ecodial will use to size the required capacitor bank. It corresponds to the power factor downstream of the transformer.

System frequency (50Hz) : enables users to choose products that are suitable for 60hz applications (capacitors, …).

Thermal stress compliance (No) : enables Ecodial to check out that cables chosen are in compliance with thermal stress under short circuit.

General characteristicsCalculation / General characteristics

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SIS - Franck MEGRET - June 2004 - English

Characterisrics spread down

One will be able to modify some of these characteristics afterwards. Ecodial will then ask whether the modified characteristic should be spread abroad down the electrical network or not. This function can be quite useful in case the user is looking quickly for the results of a variant of its own design

Spreading propertiesCalculation

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Sources : Transformer, Generator, Undefined,

(Bus coupler) Busbar : Busbar, (interlock)

Feeders circuits

Loads : receiver, motor, lighting, variable speed drive

LV / LV transformers (isolating, step-up, step-down)

Miscellaneous : graphic links - project links

Drawings

Standard diagrams

Drawing the network - the symbol toolboxDisplay / Symbol Toolbox

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Drawing the network

Click on the symbol you wish to use: the mouse pointer becomes this symbol

Click on the diagram where you wish to place the circuit Ecodial verifies if this circuit can be placed there (if there is room, etc…)

Double- click on the circuit, and define : Name Characteristics (cable length, polarity, etc…) Customise (cable busbar trunking, circuit breaker fuse, …)

Validate

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Zoom : drag a box around the area to zoom into

Grid

Alf F3 = search for a particular circuit based on its name or ID

Circuit selection (multiple) : keep SHIFT button pressed while selecting multiple circuits, or draw a box around the circuits to select.

Moving circuits : drag and drop the selection

Copying circuits (including the characteristics) select circuit to be copied CTRL+C and then CTRL+V Edit / Copy and then Edit / Paste

Enlarge busbars : select busbar, click on , enlarge bars.

Advanced editing

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B2

Switchboard

Q1

Source

C1

T1

Q5

Main lighting

C5

D5 Main lighting

E5

Q4

K4

Main motor

C4

M4

Q3

Main Load

C3

L3

The first study

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select circuit and (F4), or double-click on circuit Name all the circuits :

- Supply, Switchboard, Main Load, Main Motor, Main Lighting Enter circuit parameters:

- Main Load : 35m, 238A

- Main motor : 39m, 110kW (mechanical),

- Main Lighting :15m cable, 30m busbar, 20x150W Incandescent lights, 10 identical circuits

Useful tools Network / Item lists …

- faster input of circuit characteristics once the circuits are named. Network / Logical check (F3)

Definition of circuit characteristicsNetwork / Circuit description

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Automatically calculates the theoretical power of transformer and generator. (400kVA)

Automatically calculates the currents in the different branches of the circuits. (ex Total Switchboard feeders = 436.36A)

Ku and Ks coefficients can be used to optimise design.

Ecodial will recommend a transformer size.

Power sum should be run after every modification !

The Power SumCalculation / Power Sum

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The Power Sum is not compulsory.

But then the user must manually define the currents in every circuits. Advantage : quicker calculations :

- Do not have to draw/enter all the circuits.

- Enter only the circuits one wants to calculate, and expected current. Disadvantage : results can be sometimes surprising !

POWER SUM IS RECOMMENDED IN BIG PROJECTS !

The Power SumCalculation / Power Sum

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When single phases are connected to a three phase board, Ecodial can automatically suggest a phase distribution solution

The automatic distribution can be modified.

The logic applied is the followingEcodial sorts the loads by decreasing intensity.Starting from the highest load, Ecodial will place the loads onto the first phase until the sum of these loads is equal to 33% of the total loadEcodial then tries to load the second phase until the sum of these loads reaches 50% of the remaining loads.All the loads that remain are then allocated to the third phase.

This systems gives the best possible distribution in most cases. It is always possible to manually modify the result.

The upstream circuit is sized on the highest phase loading.

The Power SumLoad distribution

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Automatic mode - equipment is selected automatically.

- No additional entry is required, Ecodial uses default values (installation method, cable type,…)

Manual mode - parameters can be defined by user, and then they are checked to see if they verify all the

safety criteria.

- An unsafe choice will not be allowed to be validated.

Equipment calculated- Circuit breakers (and fuses) and isolators

- Contactors and relays

- Cable, BTS, and busbar

The CalculationCalculation / Calculate

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Load current and breaking capacity identifies circuit breaker

Choice of circuit breaker sets thermal setting

Thermal setting defines minimum theoretical cable CSA

Verification of cable (Sp, Sn, Spe theoretic) voltage drop protection against indirect contact short circuit currents

Sizing constraint (overload, voltage drop, user, …)


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Busbar sizing : For main busbar, size is defined by the circuit breaker protection which is defined by the

nominal current of transformer (and not the sum of the load currents !) For other busbar (sub DB) : sizing according to circuit breaker protection, which is defined

by the load current.

Short circuit currents Ik max : cold short circuit (copper is cold-low resistivity) Ik min : warm short circuit (copper is warm - high resistivity) Ik3 : three phase ‘bolted’ fault Ik2 : phase - phase fault Ik1 : phase - neutral fault Earth fault : phase-earth fault


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The CalculationResistivity values

o : resitivity at 20 degrees Celcius (IEC909) copper : 18,51 aluminium : 29,41

At different temperatures : PVC

1= 1,2x o at 70 degrees

2= 1,38x o at 115 degrees (if S <= 300 mm²)

2= 1,34x o at 105 degrees (if S > 300 mm²

3= 1,30x o at 95 degrees (if S <= 300 mm²)

3= 1,26x o at 85 degrees (if S > 300 mm²) PR




Linear reactance (non armoured cables) multi core or single core in trefoil : = 0,08 single core, flat touching : = 0,09 single core, spaced : = 0,13

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The CalculationShort circuit currents (values of resistivity to be used)

Ik3max, Ik2max and Ik1max : o

Ik2min and Ik1min for circuit protected by fuses : 2

for circuits protected by circuit breakers : 1

If (earth fault current) TNC :

- for circuit protected by fuses : 2

- for circuits protected by circuit breakers : 1 Multicore, PE included


- for circuits protected by circuit breakers : 1 PE separate


- for circuits protected by circuit breakers : 1

Voltage drop : 1 : = 0,13

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B7

Emergency DB

B2

Switchboard

C6

Emergency DB feeder

Q6

Q8

C8

Emergency supply

G8

L9

C9

Vital Load

Q9

M10

C10

Vital Motor

K10

Q10

Q5

Main lighting

C5

D5

Main lighting

E5

Q4

K4

Main motor

C4

M4

Q3

Main Load

C3

L3

Q1

Source

C1

T1

The second study

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Define new circuits : Emergency DB feeder : 45 m , (I = ???) Emergency DB Emergency supply Vital Load (36m, 135A) Vital Motor (75m, 18,5 kW mechanical)

Run Power Sum Transformer : 400 to 630 kVA Generator : 160 kVA (only supplies Emergency board !)

Run Calculation

Modify the circuit

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Under ‘Emergency’ supply, only the board under the ‘Emergency’ feeder is considered fed. All the other loads (those connected to the main DB are considered disconnected).

The ‘Normal’ source is sized on the sum of all the loadsThe ‘Emergency’ source is sized ONLY on the loads on the ‘Emergency’ board.

For those feeders that can be fed by either the ‘Normal’ or the ‘Emergency’ supply, the worst case parameters are used to verify the selection and sizing of the equipment :

max 3 phase short circuit currentmin earth fault current

Normal / Emergency supply #1

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Normal / Emergency supply #2

Sources sizing : Transformer T1 is sized for circuits 6 to 9 : 315kVA Generator G5 is sized for circuits 8 to 9 : 100kVA

Short circuit level : Maximum IK3maxis given by the transformer Minimum earth fault current = minimum from the two

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Power (kVA) : the nominal rating of the transformer. It is usually calculated and set in the power sum, nonetheless it can be manually set by the user here.

Type : choice between immersed or dry transformer Earthing arrangement : a reminder of the earthing

arrangement set in the general characteristics. Modifying the earthing arrangement here does not modify the earthing arrangement of all the downstream circuits.

Distributed neutral : networks have or not neutral conductor. Un Ph-Ph : a reminder of the system voltage. If change, Ecodial

will propose to spread down this property downstream. Short circuit voltage : since version 3.36, Ecodial reads values

of transformer’s reactance and resistance in tables 2A&2B of the UTE 15 106.

High Voltage short circuit power : short circuit level on the medium voltage side of the transformer. Enables Ecodial to read in tables 2A&2B to determine cross section area

Connection : the different windings of the MV/LV transformer (Delta-star; star-star; zig-zag)

HV operating time : time used to read in tables 2A&2B of the UTE 15 106 , the cross section area

Neutral & earth electrods resistance : use to calculate the imedance loop

Circuit descriptionTransformer

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Circuit description PE Cable Cross section area from transformer (2)

Immersed transformer

Dry transformer

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Circuit descriptionTransformer (3)

Results :

R and X of MV network (using CENELEC R064-003 formulas)XQ= 0,995 x ZQ RQ=0,1 x XQ

R and X of transformer : either read values onto tables given by CENELEC harmonised documents HD 538.1 / HD 428.1

Ib : rated current of the transformer (In)

Isc max (maximum short circuit current at the terminals of the transformer)

Copper losses (heat loss)

No load voltage coeficient Difference between IEC 909 and CENELEC R064-003 IEC 909 considers that Un is the no load phase phase voltage. CENELEC R064-003 considers that Un is the load voltage. It is required to introduce a corrective factor.

kQQ S

UnZ

2)05,1(

TRInPcu 23

Un

SIn rT

3

upstream

kZ

UncIIsc

3

05,1maxmax3

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Circuit descriptionTransformer (4)

Dry transformer (NFC 52 115 - CENELEC HD 538.1 )

Immersed transformer (NFC 52 112 - CENELEC HD 428.1 )

Ecodial interpolates for missing Power values

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Circuit descriptionGenerators

Power (kVA) : the nominal rating of the transformer. It is usually calculated and set in the power sum, nonetheless it can be manually set by the user here.

Earthing arrangement : a reminder of the earthing arrangement set in the general characteristics. Modifying the earthing arrangement here will request spread down function.

Distributed neutral : networks have or not neutral conductor. Un Ph-Ph : a reminder of the system voltage. If change, Ecodial

will propose to spread down this property downstream. X’o (%) : zero phase impedance, 6% by default or manufacturer

value X’d (%) : Transient reactance, 30% by default or manufacturer

value X’’ (%) : Subtransient reactance, 20% by default or

manufacturer value Neutral & earth electrods resistance : use to calculate the

impedance loop

Ecodial uses the subtransient reactance to calculate the maximum short-circuit currents for networks supplied only by generator.

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Circuit descriptionAny source

Un Ph-Ph : a reminder of the system voltage. If change, Ecodial will propose to spread down this property downstream.

I service connection (A) : Intensity of the connection, in other words the current rating of the upstream protection device (not drawn on the diagram).

Earthing arrangement : a reminder of the earthing arrangement set in the general characteristics. Modifying the earthing arrangement here will request spread down function.

Distributed neutral : networks have or not neutral conductor. Neutral & earth electrods resistance : use to calculate the

impedance loop Ik3max (kA) : maximum prospective short circuit current at a

the feeding point Ik1min(kA) : minimum phase neutral prospective short circuit

current. This value is used to calculate the ‘warm’ impedance of the Phase/Neutral loop.

If (A) : fault current Short circuit power factor : power factor under short circuit Initial dU (%) : existing voltage drop at the delivery point. Energy supplier : choice between several public utilities

(Ecodial adaptation requested)

Ecodial uses a specific algorithm that depends on the earthing system.

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Circuit descriptionAny source (2)

Connection system drawing

Characteristics fields

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Why having such a complex algorithm?

The calculations made in Ecodial 3.2 were based on a number of simplifying assumptions that neglected the following problems:

The real constitution of a power supply network that can be a mixture of generators, transformers and cables of varying lengths.

The distance to the point where the neutral is created. For example, if a delta-star transformer is located just upstream, the neutral impedance is zero. On the other hand, if the cable impedance is high with respect to that of the transformer and the HV system, the neutral impedance will be close to that of the phases.

Upstream earthing location and method. This is particularly a problem TN systems, where the fault current could be confused with a single-phase short-circuit, while there is a very high probability of an equipotential link at the connection point.

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Factors Cmin and Cmax, along with the resistivities 0, 1 and 2 of the circuits, are used to distinguish between the maximum and minimum short-circuit current values.

However, what types of circuits are concerned, what are their lengths and what resisitivity values should be applied?In this concern, UTE C 15 500 considers RQ and XQ, with RQ invariable with respect to temperature.

The ratio R/X of the different impedances. Ecodial 3.3 offers the possibility of entering an additional value, the power factor under short-circuit conditions, that is applied for Ik3max and Ik1min. Of course, taking the same short-circuit power factor for Ik3 and Ik1 leads to an approximation in the calculation of the neutral and PE impedances.

A test is required to check for consistency between the values entered for Ik3max and Ik1min.

Ecodial 3.3 offers the possibility of checking Ik1min with respect to Ik3max. According to the characteristics (system earthing arrangement, distributed neutral, reduced neutral, etc.), incompatibilities will be corrected and the user will be asked to confirm certain assumptions.

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What to do when I have no information ?

When no information are known about the upstream network, the UTE (French standard) proposes to consider the following assuptions:

Earthing system : TT

HV/LV transformer 1000kVA, Usc 6%

15 meters distance, 240mm² aluminium single core cable, installed on to punched cable trays.

It is upto the designer to adapt these assumptions to match its project.

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Circuit descriptionCapacitor

Power factor before compensation : value of the power factor calculated in the Power Sum (the Power Sum must be run to calculate a Capacitor bank)

Power of the Harmonic sources : In order to take into account the effect of harmonics on the capacitors, Ecodial needs the power of all the harmonic generating (non-linear) loads on the network. This value is used in conjunction with the transformer size to identify the type (Standard, H or SAH) of capacitor used by Ecodial.

Power (kvar) : Total power of the capacitor bank needed to attain the target power factor.

Type of compensation

Step : resolution of the automatic capacitor bank : ex 5x50kvar means the capacitor bank can go from 0 to 250kvar in steps of 50 kvar (controlled by the regulator)Ib : current drawn by the capacitor bank (inclusive of possible harmonic currents and manufacturing tolerances)

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Ih L, C,

Transformer(PT)

Capacitor(Q)

Harmonic current injection

Equivalent impedance of L-C circuit (resistances ignored)Z= j.L./ (1-L.C.²)

Resonance when ²=(2f)²=LC (Zmax induces to Voltage max)order of resonance :

if order of resonance is close to harmonic current injection, filtering devices

could be required.

Harmonic voltage created across the equivalent impedance of the transformer and capacitor, which causes circulating currents in the L-C loop, which can be a cause of nuisance tripping in transformer or capacitor protection devices.

c

T

Qucc

Pn

(%)

Circuit descriptionCapacitor

Vh

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Logic diagram for the selection of cable size and protection devices

short-circuit MVA at the origin of the circuit

Isc

upstream ordownstream network

choice ofprotective device

kVA to be supplied

short-circuit currentmaximum load current

IB

short-circuit current-breaking rating of C.B. or fuses

rated current of protective device (C.B. or fuses)

verification of thermal withstand requirements

verification of the maximum length of

the circuit

confirmation of the cross-sectional area of the cabling, and the choice of its electrical protection

determination of thecross-sectional areaof the conductors

IscbIn

cross-sectional area of conductors of the circuit

choice of C.Bor fuses

conditions of installations

TT scheme

IT or TN scheme verification of the maximum

voltage drop

specifications

estimated power (kw)

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The difference between a protection by fuses or C.B.

fuseIz = 1.31 In In < 10AIz = 1.21 In In > 10A < 25AIz = 1.10 In In > 25A

circuit-breaker

In or Ir

I'z =Iz

Kconductor cross-section I'z =In or Ir

K

installationconditions

K1. K2 .K3 = K

apparent power to convey

operational current IB

protective devicerated current

choice of protective device

short-circuit power at origin of circuit

short-circuitcurrent

protective devicebreaking capacity

IB

In or Ir

ICC

bc

Checking maximalvoltage drop

configuration of choice of duct cross-section and electrical protection

Checking maximumduct length

IT or TN system

TT system

upstream or downstrea m network

choice ofprotective device

determination of conductor cross-section

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Overall calculation algorithm

Estimated power

Calculation of service current iB

Choice of the protection device & its trip unit

Calculation of the cable size

Verification of the volatge drop

Calculation of the short circuit current

Choice of the breaking capacity

Verification of the cable stress

Discrimination

Cascading

Verification of the max length of IT & TN circuit

Confirmation of the cross section area

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Circuit descriptionCircuit breaker (distribution)

Range : Product range from which the circuit breaker is to be chosen. If Ecodial cannot find a breaker in that range it will look for a breaker in a predefined range (function of the demand current)Designation : name of circuit breakerTrip unit / curve : name of the trip unit or curve of the circuit breakerNb of poles protected : polarity of the circuit breaker that is required.Fire protection : this is a characteristic that will force an earth leakage device, and set it to ensure that a leakage current will not be able to cause a fire (threshold < 300mA)

Integrated with the protection device : certain RCDs are integrated (NS Vigi, …) and certain are separated (RH***). The user can choose the type of RCD required. By default, Ecodial looks for integrated RCDs, and then separated RCDs if unsuccessful.Class : (A / AC ) defines the sensitivity of the RCD to continuous and pulsed DC signals. Earth leakage protection device : name of the device ensuring the function of RCD.

Earth leakage protection : if earth leakage protection (RCD) is required (by user, or for a particular application, switch this characteristic to YES).

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Sensitivity (mA) : pickup current of the RCD deviceDelay (ms) : time delay before disconnection under earth fault conditionsI thermal setting (A) : Thermal setting of the circuit breaker. This value is set to be greater or equal to the demand current, and is used to size the cable.I magnetic setting (A) : magnetic setting of the circuit breaker. This setting s made to ensure protection against indirect contact in TN, and to ensure correct motor starting based on start-up currents.Frame rating (A) : maximum rating of the circuit breaker frameTrip unit rating (A) : maximum setting of the trip unit.Im/Isd : position of the magnetic adjustment on the trip unitIr : position of the thermal adjustment on the trip unitIo : position of the thermal adjustment on the trip unitMotor mechanism : breakers must be able to be fixed with a motor mechanism

Circuit descriptionCircuit breaker (distribution) (2)

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Cascading requested : YES : circuit breaker is chosen using cascading with the upstream device (only the device directly upstream)NO : circuit breaker is chosen based on its stand-alone breaking capacity.

Discrimination requested :YES : circuit breakers that have better discrimination potential are selected instead of normal circuit breakers

Installation : Fixed breakers or withdrawable breakers

Circuit descriptionCircuit breaker (distribution) (3)

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Circuit descriptionCircuit breaker (motor)

Range : see previousDesignation : see previousTrip unit / curve : see previousContactor : name of contactor to be used according to the co-ordination tablesThermal protection : name of thermal overload (if needed) according to co-ordination tables.Fire protection :see previous with the added safety that the tripping time is delayed by at least 60ms to ensure there is no nuisance tripping on start-up.Soft starter : name of soft starter (if needed) according to co-ordination tables.Earth leakage protection : see previous.Number of poles protected : always 3P3T, as Ecodial does not cover single phase motorsI thermal setting (A) : Thermal setting of the circuit breaker. This value is set to be greater or equal to the demand current, and is used to size the cable.I magnetic setting (A) : magnetic setting of the circuit breaker. This setting s made to ensure protection against indirect contact in TN, and to ensure correct motor starting based on start-up currents.

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Frame rating (A) : maximum rating of the circuit breaker frameTrip unit rating (A) : maximum setting of the trip unit.Im/Isd : position of the magnetic adjustment on the trip unitIr : position of the thermal adjustment on the trip unitIo : position of the thermal adjustment on the trip unitMotor mechanism : breakers must be able to be fixed with a motor mechanismCascading requested :

YES : circuit breaker is chosen using cascading with the upstream device (only the device directly upstream)NO : circuit breaker is chosen based on its stand-alone breaking capacity.

Discrimination requested :YES : circuit breakers that have better discrimination potential are selected instead of normal circuit breakers

Installation : Fixed breakers or withdrawable breakers

Circuit descriptionCircuit breaker (motor) (2)

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Circuit descriptionLoad (1)

Number of identical circuits : instead of drawing multiple feeders having EXACTLY the same characteristic, just draw one !

Ib : demand current of the load (calculated from the power and polarity)

Circuit polarity : polarity of the load

Earthing arrangement : see previous

Power (kVA) : demand power (calculated from the current and the polarity)

Power factor : power factor of the load (.8 is default value)

Ph/earth fault max turn off time :User may have the ability to force to 5s the tripping time of the breaker, but in TNC/TNS.

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Circuit descriptionLoad (2)

Load type & environment:

Load type : Ecodial offers you a variety of choices: standard, corresponding to the general case, or certain special cases: heating floor – Instrumentation/measurement – Public lighting – luminous signs – computers

Environment : various choices are pre-selected: standard, corresponding to the general case, or certain special cases.

Depending of both characteristics Ecodial will force RCD protection and in some cases will propose a SI type from the Multi 9 range. That’s specially the case when the load is considered as mobile : terminal load is fed through a power socket (special earth leakage conditions are then applicable : 30mA and Instantaneous protection is required)

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Circuit descriptionMotor

Type of starting : for Direct on Line or Soft Starting applicationsMechanical power (kW) : rated mechanical power of motorMotor efficiency : ratio between mechanical and electrical power (in kW)Ib (A) : full load current of motor Circuit polarity (always 3P) Power factor : full load power factor of the motorEarthing arrangement : see previousPower (kW) : demand power (calculated from the efficiency)Type of co-ordination : Type 1 or Type 2Number of identical circuits : see previousStarting class : Standard / LongId/In : ratio between inrush and nominal current .Start-up current sets the magnetic setting of the breakerPh/earth fault max turn off time : see previous

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Type1 and Type2 co-ordinationIEC60947-4

Association between the protection (thermal and magnetic) and control devices.Defines safety and maintenance levels of the association (IEC60947-4).These associations are verified/proven through testing at levels defined in the standards (corresponding to extreme conditions on the equipment)

Type 1 : damage is accepted on the contactor and the thermal relay under the two following conditions :

there is no risk for the operatorother elements must not be damagedmore maintenance required, poor continuity of service, cheaper equipment

Type 2 : it is acceptable for the main contacts to solder ‘lightly’ : they can be easily separated...

little maintenance required, continuity of service improved, more expensive equipment

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Circuit descriptionLighting

Number of identical circuitsLighting Source : type of lampIndividual lamp power :Number of lamps per light : for each lighting point there can be several lampsNb of lights (A) : total number of lamps on the Canalis lighting line Ib : full load current at the origin of the Canalis lighting distributionBallast power : for lamps using ballasts (fluo tubes, …)Circuit polarity Earthing arrangementPower (kW) : total demand power (calculated)Power factor : individual lamp’ s power factorPh/earth fault max turn off time : see previousEnvironment : see previous

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Circuit descriptionSocket

Number of identical circuitsIb : load current of the total distributed socketsCircuit polarity Earthing arrangementPower (kW) : total demand power (calculated)Power factor : total expexted power factorPh/earth fault max turn off time : see previousLoad type & environment : see previous

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Circuit descriptionVariable Speed Drive

Reference : name of VSDVSD IP : level of dust & water protection level (will define VSD type range)Permitted transient torque (A) : starting torque (High or standard)

This information is directly linked to the type of application (lift, roof top fan, liquid pump, etc…) Note : a VSD can work either with a standard or high transient torque (especially for motors over 15kW). Electrical characteristics fluctuates

Transient overtorque value (%) : value of permitted transient overtorqueHeat power consumed : VSD heat loss (value from VSD data base)Nominal power of the VSD (kW) : characteristic of VSDForm factor (K): ratio between total RMS and 50Hz signal (characteristic of VSD)Ib consumed by the VSD : current drawn by VSD (including losses)Called current : inrush currentMaximum deliverable nominal current : permanent Is output currentMaximum transient current for 60s/10min : output current Is maximum 60s (characteristic of VSD)Earthing arrangementCircuit polarity

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Circuit descriptionVariable Speed Drive (2)

VSD selected based onfull load current of the motorpermitted transient torque (A) = type of starting : standard or high torque VSD Ip ratings ( if low IP, ATV38 is selected)Voltage range : ATV 68/38 have various characteristics depending of voltage

Active power supplied by VSD:kWe= kWm / motor efficiency)

Heat dissipation power by VSDPl (function of the VSD selected)

Power drawn by VSDpower factor = 1kVA = kW = kWe + Pl

Ib consumed by the VSDk = form factor linked to presence of harmonics (function of VSD)Ib = kVA / (1,732 x V) x k

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Circuit descriptionCable

Length : length of the cable (Short circuit and voltage drop calculations)Installation method : code for the type of installation. Defines the standard derating factors and the type of conductors used.Insulation : sets the insulation material of the cable (impedance calculation)Type of conductor : output from the Installation method, not an input !Neutral loaded : source of derating on 3P+N networksConductor arrangement : calculation of the linear reactance of the cableType of PE : influences the type of cables selected by EcodialNumber of additional circuits : cable deratingNumber of layers : cable deratingK user : additional cable derating (over and above the standards)Ambient temperature : cable deratingDelta U max on circuit (%) : maximum voltage drop allowed on the cableReference : name of cable

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Circuit descriptionCable (2)

Nb Ph conductor : calculation resultCSA Ph conductor : calculation resultNb N conductor : calculation resultCSA N conductor : calculation resultNb PE conductor : calculation resultCSA PE conductor : calculation resultPhase metal : cable characteristic (input)Neutral metal : cable characteristic (input)PE metal : cable characteristic (input)Safety voltage : 50V or 25V

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Ecodial and the earthing schemesImplementing protection against indirect contact

TTEarth fault current (leakage) calculated using the impedance of the source and earth electrodes, and the Phase-Earth conductor impedanceStandards require an RCD device on the main incomer the earth and source electrodes must not be interconnected !

TNEarth fault current calculated using the Phase-Earth conductor impedanceProtection against indirect contact ensured by setting the magnetic under the Earth fault currentTrip units can be changed to ensure accurate magnetic threshold is usedRCDs can be implemented

IT (2nd fault)identical calculations as for the TN systemEarth fault current is calculated assuming both fault occur at the same point. This ensures ‘worse case scenario’ as if the second fault appears further away, the real fault current on the 2nd fault would be greater than the calculated fault current corresponding to the 2nd fault location, and ensuring tripping by the 2nd fault location protection device.

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Calculation rulesPhase CSA

a

m

Irth

KSth

11

Theoretical Phase CSA : calculated by a formula, where (IEC 60364-5-523-B):K is the total derating (temperature laying method, cables in parallel, …)Irth : is the thermal setting of the upstream breakerm and a : parameters defined by the laying method and the type of cable (metal, insulator) andthe number of loaded conductors in the circuit)

Choice of Phase conductorbased on cable database suppliedbased on theoretical phase CSA and tolerancebased on installation rules (ex TNC Smini = 10mm²)based on limits implied in the standards (ex Smini for multicore conductors on perforated tray = 25mm²)based on maximum phase CSA allowed

Voltage drop is calculated on this cable using demand currentCSA could be increased

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Calculation rulesNeutral CSA

Theoretical calculation made by Ecodialminimum theoretical CSA equal Ph or Ph/2

Warning : the Neutral, as any cable, should be sized according to the upstream protection setting (this is to ensure safety)

With 4p4t CB, the neutral can be of the same CSA of the PhaseWith 4p3t 1/2N, the neutral can be halfWith 3p devices (Neutral not protected), there is an unknown, as there is no direct protection on the neutral…

Phase unbalance can lead (worse case scenario) to a phase current equal to neutral current, so Neutral should be at least equal to Phase

Triplen Harmonics see specific rules

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Calculation rulesNeutral CSA

Recommended actions :use half neutrals

when there is a 4p3t N/2 circuit breaker protecting the circuit, and if there is no possibility of excessive phase unbalance and/or triplen harmonic loading on the circuit.Note : 3p3t are acceptable solutions, but 4p3t N/2 offer more safety under unexpected conditions

use full neutrals when there is a 4p4t circuit breaker protecting the circuitand if there is a possibility of excessive phase unbalance, or limited triplen harmonic (max allowed = 33% triplen in the RMS)Note : 3p3t are acceptable solutions, but 4p4t offer more safety under unexpected conditions

use double neutralswith 3p3t circuit breakerswhen there is a high risk of excessive triplen harmonic

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Calculation rulesPE CSA

Automatic minimum PE :if Ph 16mm², PE = Ph x kph/kpeif Ph 35 mm², PE = 16mm² x kph/kpeif Ph > 35 mm², PE = Ph/2 x kph/kpewhere kph and kpe function of the type of phase and earth conductor (metal, insulation, single/multi core, …)in TT, max PE = 35mm²

Theoretical minimum PE : the theoretical minimum PE cross section should only verify the I²t < k²S² condition, as very little current is ever expected to flow on the PE (as it is an equipotential link). This condition usually implies small PE cross sections (+/- 4mm² in TN and 1mm² in TT). Using such small cables has two bad consequences :

reducing Earth fault current (due to higher loop impedance), which could require the use of earth fault protection devices or lowering the magnetic thresholds to non efficient levels (motor starting and discrimination problems)creating a higher voltage differential on the PE due to natural leakage currents Ecodial chooses automatically the CSA given above, but allows smaller cables to be selected by the user.

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Network General characteristics

- TNS

- 400V Transformer

- 800kVA transformer

- Incomer cable length = 0 Load

- 3P+N

- 160A

- Installation method 14,touching, multicore, trefoil

- THDI<15%

Calculate the network with : Load cable length =30m, 100m, 140m, 170m Info needed : Irm, If, Sph, Spe, DeltaU, CB, Sizing criteria

Tableau

B2

T1

C1

Circuit

Q1

Q3

Circuit

C3

L3

Calculation examplesthe effect of long cables

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Calculation examplesthe effect of long cables

Cable sized on upstream thermal setting Cable sized on voltage dropSetting of trip unit to cater for low earth fault current (protection against indirect contact)To ensure disconnection in sufficient time, Ecodial verifies that the earth fault current is higher than the magnetic setting of the breaker (including tolerance).

• Trip units can be changed to ensure this :C curve to B curve (Multi9 breaker)TM to STR (NS breaker)

• Cable size can be increased• If no solution is found Ecodial interrupts the calculation requesting the user to manually place an RCD on the circuit breaker to ensure disconnection, and therefore protection against indirect contact.

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Non-uniformly distributed load the Icc and DeltaU can be calculated at each tap-off point, or for worst case scenario (Icc at

source) Calculation method to be used for distribution systems having loads that vary substantially in

power and location.

Uniformly distributed load the Icc is calculated at the beginning of BTS. The voltage drop is estimated as a function of the number of tap-offs Calculation adapted for distribution systems having evenly distributed loads (in power and

location)

Calculation examplesPrefabricated busbar trunking

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Uniformly and Non-uniformly distributed load. 800kVA 100A tapoffs D=5,10,15,20,25 Total length 30m Info needed :

- Icc, deltaU per tap/off.B2

Tableau

D4

CEP

Q8

Circuit

C8

L8 L9

C9

Circuit

Q9

Q7

Circuit

C7

L7L6

C6

Circuit

Q6

Q5

Circuit

C5

L5

Q3

Circuit

C3

Q1

Circuit

C1

T1

Calculation examplesPrefabricated busbar trunking (2)

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Ku : usage coefficient applicable to a CIRCUIT % full load current when load is running example :

- motor +/- 80%

- Light 100%

Ks : diversity coefficient applicable to a DISTRIBUTION BOARD chance of all feeders drawing maximum load at any given time relative to the number of feeders on DB. See Electrical Installation Guide

The Power sum, KS & KuDiversity and usage coefficients

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The Power sum, KS & Ku#2

Ib is the maximum current potentially consumed by the load.

Therefore, Ecodial makes sure to take the worst case if considering the maximum Ib.

Ib will size the frame and the overload protection of the protective device.

Consequently Ecodial does not consider the Ku input for the load.

In three phases system :

In single or bi phase systemcosNPh

kWb U

PI

cos3 PhPh

kWb

U

PI

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Ku is a user coefficient.

If the user knows is equipment load will be only 80% of the nominal current, he should input 0.8. These kind of assumptions are quite common for motors.

Ku is not used to size the macro component. He is taken into account to size the upstream circuits

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73



154.6 36.24

74



154.6

75



154.64240.86110.94

76



154.64240.86110.94

77



78



The power required is equal

In three phases system

In single phase system

In Bi phases system

m is the Voltage coefficient that is requested to alleviate Voltage fluctuation. Standards has fixed it to m = 1.05

3bPhPhkVA ImUP

bNPhkVA ImUP

bPhPhkVA ImUP

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Lathe 1 5.5 kWLathe 2 5.5 kW

Distribution box Lathe 3 5.5 kWLathe 4 5.5 kW

Workshop A Drill 1 2.2 kWDrill 2 2.2 kW

3x socket outlet circuit (1P+N) 20 A each6x lighting lines (1P+N) 10x 100W each

Compressor 15 kWIncomer Workshop B 5x socket outlet circuit (1P+N) 20 A each

4x lighting lines (1P+N) 4x 100W each

Ventilation Fan 1 2.2 kWDistribution box Ventilation Fan 2 2.2 kW

Oven 1 15 kWWorkshop C Oven 2 15 kW

10x socket outlet circuit (1P+N) 20 A each2x lighting lines (1P+N) 2x 100W each


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Apartment blocks :

Consumers 4 9 14 19 24 29 34 39 49

Ks 1 .78 .63 .53 .49 .46 .44 .42 .41

Distribution Boards (IEC439) :

Circuits 3 5 9 10+

Ks .9 .8 .7 .6

Circuits (Ks or Ku ?): Lighting 1 Heating, air conditioning 1 Socket outlet circuit .1 to .2 (higher in industry) Lifts/hoists 1 / .75 / .6


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Problem with Ku and Ks Responsibility of the user Personal experience Knowledge of installation Database of existing installations

Advantage of Ku and Ks more cost effective installation not oversized Example

- total installed power : 144kVA

- maximum expected demand : 80 kVA


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Circuit breaker and busbar selection Discrimation and cascading tables Tripping curves

Guides and tools

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Maximum number of circuits in a project : 200 Maximum number of copied circuits : 50 Maximum number of transformers : 4

Network calculation limitation

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Short circuit limitation : why ? Installation of current limiting circuit breakers offers several advantages

current limiting circuit breakers considerably reduce the undesirable effects of short-circuit currents in an installation.

cable heating is reduced hence longer cable life. electrodynamic forces reduced, thus electric contacts less likely to be deformed or

broken. measuring equipment situated near an electric circuit less affected the cascading technique offers substantial savings on equipment, enclosures and

design by using lower rated devices downstream.

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Principle of limitation

prospective current

limited current

arc voltage

network voltage

U arc

i u

I limited

t

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Limitation : how The limiter block operates in a similar manner to the main poles of the circuit breaker

but is not linked mechanically to the main poles or to the tripping mechanism of the circuit breaker.

This allows the limiter contacts to re-close after fault interruption. Isolation is then provided by the circuit breaker contacts.

II

Fr

Fm

I I

Fm

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What it is limitation : tables to use for applications circuit breaker limitation capability : the

limitation capability of a circuit breaker is that characteristic whereby only a current less than the prospective fault current is allowed to flow under short-circuit conditions.

withoutlimitation

withlimitation

kA peak

kA rms300

25

55

prospectiveIsc peak

prospective Isc

limited Isc

limited Isc peak

t

Isc

total energy let through duringhalf cycle without limitation

I2t

kA rms300

6 x 106 energy let through duringhalf cycle with limitation

9 x 106

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Definition : discrimination discrimination (selectivity), is the coordination of automatic protective devices in such a

manner that a fault appearing at a given point in a network is cleared by the protective device installed immediately upstream of the fault, and by that device alone.

no discrimination

CB1

CB2

CB1 and CB2 open

discrimination

CB1

CB2

only CB2 open

why is discrimination useful ? Discrimination contributes to continuity of service, a necessity in many industrial, commercial or institutional installations.

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Full or restricted discrimination Full discrimination

i²t

D2

D1

i²t

D2

D1

Is I

Restricted discrimination

D2

D1Icc

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Definition : cascading cascading is the use of the current limiting capacity of circuit breakers to permit

installation of lower rated and therefore lower cost downstream circuit breakers.

the principle of cascading has been recognised by the IEC 364-434.3 standard

cascading can only be checked by laboratory tests and the possible combinations can be specified only by the circuit breaker manufacturer.

comments : the upstream CB acts as a barrier against short-circuit currents. They thus allow circuit breakers of lower breaking capacity than the prospective short-circuit current at their point of installation to operate under the stress conditions of normal breaking.

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Harmonics : introduction of specific cable sizing Triplen harmonics :

Origin : harmonics are created by non linear loads that absorb current in a form a discrete peaks . Harmonics are generated by DC adpater, fluorescent tubes, wheastone led circuit..

(3rd, 9th, …) add up on the neutral. Therefore, if the phase is ONLY 3rd harmonics, neutral current = 3x phase current. In reality, the neutral current will usually be less than 1.7-1.8 times the phase current, example ;

Irms (phase) = (I1, I3 (80%), I5(45%), I7(12%)) = 1.36x I1 Irms (neutral) = 3x I3 = 2.4x I1 = 1.76 Irms (phase)

The NFC15-100 has introduced in 2003, rules for the calculation of CSA of conductors. It defines the THDI, harmonics rate in current as

Typical values of the THDI and impact onto the LV installation

- a value lower than 15% is considered as normal. No running disturbance is to be feared. Neutral conductor is not loaded.

- Between 15 % and 33%, one considers harmonics polution as medium. There is a risque of over heated cables, that induces oversizing of cables from sources. Neutral is loaded.

- Ocer 33%, one consoders harmonics polution to be severe. Runing disturbances will occur. It must be analysed accurately and some specific tripping unit might be required.

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Harmonics : cable sizing

THDI <= 15% 15%<THDI <= 33% 33%<THDI

Single core cable

multicore cable,

CSAph<16mm² (Co), 25mm² (Al)

multicore cable,

CSAph >16mm² (Co), 25mm² (Al)

single cable,

CSAph >16mm² (Co), 25mm² (Al)

CS N <= CSA Ph CS N <= CSA Ph CS N = CSA Ph

CS N = CSA Ph CS N = CSA Phk=.84

CS N = CSA PhNeutral determine Ph

Ib N = 1.45 Ib Phk=.84

CS N = 1/2 CSA PhNeutral protected

CS N = CSA Phk=.84

CS N = CSA PhNeutral determine Ph

Ib N = 1.45 Ib Phk=.84

CS N = 1/2 CSA PhNeutral protected

CS N = CSA Phk=.84

CS N > CSA PhNeutral determine Ph

Ib N = 1.45 Ib Phk=.84

Installation IEC 364 : even IEC 364 has been fully updated yet, Schneider Electric is stating that one would have better to always take the worst case. Ecodial IEC 364 will apply the NFC 15 -100 rule.

ECODIAL 336

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