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Railway Current &Voltage Transducers

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Current and Voltage Transducersfor Railway applications

LEM solutions for traction electrical measurements

This catalogue summarizes themost common LEM productofferings for electrical railwaymeasurements. It is ourbusiness to support you withboth standard and customizedproducts to optimize yourapplication.

Please contact LEM in yourregion for assistance.

Today, high speed trains, citytransit systems (metro, trams,and trolleybuses) and freighttrains are the solutions againstpollution and interstate trafficimmobility and provide asignificant energy savings.Power electronics is essential todrive and control energy in thesetransportation systems.LEM has been a main player intraction power electronicsapplications and developmentfor the last 30 years andleverages this vast experience tosupply solutions for isolatedcurrent and voltagemeasurements.

LEM transducers providecontrol and protection signals topower converters and inverters

that regulate energy to theelectric motors (for propulsion)and to the auxiliaries (for air-conditioning, heating, lighting,electrical doors, ventilation, etc.).This includes the earlymonitoring of the voltagenetwork (changing by crossingthe European borders) to makethe powers electronics workingaccordingly.Although this is true foron-board applications, LEM hasalso provided the same controland protection signals forwayside substations.

The rail industry is underconstant changes andevolution. As a recent example,the privatization of the railnetworks raised newrequirements for which LEMprovides: the on-boardmonitoring of powerconsumption (EM4T EnergyMeter), solutions to tracksideapplications, rail maintenanceand the monitoring of points(switches) machines or signalingconditions with some newtransducers families.LEM is always available to assistin adapting to these evolving

technical applications.

Three decades of railwayexperience has contributed toestablishing LEM as a marketleader with worldwide presenceto serve you and provide theefficient, safe and reliableoperation of the railways.

With more than 2 500 currentand voltage transducers in itsportfolio, LEM offers a completerange of accurate, reliable andgalvanically isolated devices forthe measurement of currentsfrom 0.1 A to 20000 A andvoltages from 10 V to 6 400 V invarious technologies: OpenLoop, Closed Loop, Isolationamplifier, etc.

LEM transducers for railwayapplications are designedaccording to the mostdemanding internationalstandards (EN50155,EN50124-1, NFF 16101,16102, etc) and carry CEmarking. UL or UR is alsoavailable on selected models.We have worldwide ISO 9000and ISO TS 16949:2002(Geneva production and design

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center, BeijingLEM planned for2007) qualification and offer a 5-year warranty on all of ourproducts.LEM constantly innovates andstrives to improve theperformance, cost and sizes ofits products.LEM is a worldwide companywith offices across the globe andproduction facilities in Europe(included Russia), Asia andAmerica.

We hope you will f ind thiscatalogue as a useful guide forthe selection of our products.Visit our website atwww.lem.com and contact oursales network for furtherassistance. Detailed datasheetsand application notes areavailable.Sincerely,

Luc ColombelVice President & BusinessSegment Manager Traction

Paul Van IseghemPresident & CEO LEM

Content

Transducer Technologies

On-Board Applications

Substations

Energy Measurement for On-BoardApplications : EM4T

Specific Railway Applications

Mining Trucks Applications

Trackside Applications

LEM’s Quality & Standards

Solutions for Voltage Measurement

From the Application to the Product

Secondary Connections Options

Design Specification Form

Dimension Drawings

LEM’s Warranty

LEM International SalesRepresentatives

Pages

4 - 5

6 - 13

14 - 17

18 - 21

22 - 23

24 - 25

26 - 29

30 - 31

32 - 33

34 - 35

36

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38 - 42

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Operation principle C/L

Operation principle O/L

Operation principle

Transducer Technologies

Open Loop Current Transducers (O/L)Features

The magnetic flux created by the primary current IP is

concentrated in a magnetic circuit and measured in the airgap using a Hall device. The output from the Hall device isthen signal conditioned to provide an exact representationof the primary current at the output.

• Small package size• Extended measuring range• Reduced weight• Low power consumption• No insertion losses

Isolated Output Voltage VOUTPrimary Current IP

Closed Loop Current Transducers (C/L)

• Wide frequency range• Good overall accuracy• Fast response time• Low temperature drift• Excellent linearity• No insertion losses

Features

The magnetic flux created by the primary current IP is

balanced by a complementary flux produced by driving acurrent through the secondary windings. A hall device andassociated electronic circuit are used to generate thesecondary (compensating) current that is an exactrepresentation of the primary current.

Primary Current IP Isolated Output Current IS

Closed Loop C Types

Features

This technology uses two toroidal cores and two secondarywindings and operates on the principle of Ampere-turnscompensation. For the voltage type a small (few mA)current is taken from the voltage line to be measured and isdriven through the primary coil and the primary resistor.

• High accuracy• Very wide frequency range• Reduced temperature drift• Excellent linearity• Measurement of differential currents (CD)• Safety isolation (CV)• Reduced loading on the primary (CV)

Primary Current IP Isolated Output Current IS

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Operation principle

Operation principle C/L

Primary Current IP Isolated Output Current IS

A very small current limited by a series resistor is takenfrom the voltage to be measured and is driven through theprimary coil. The magnetic flux created by the primarycurrent I

P is balanced by a complementary flux produced

by driving a current through the secondary windings. A halldevice and associated electronic circuit are used togenerate the secondary (compensating) current that is anexact representation of the primary voltage. The primaryresistor (R

1) can be incorporated or not in the transducer.

Closed Loop Voltage Transducers (C/L)Features

• Measurement of high voltages• Safety isolation• Good overall accuracy

• Low temperature drift• Excellent linearity

AV 100 types Voltage Transducers

The voltage to measure (VP) is directly applied on theprimary connections through an internal resistor networkand some components allowing the signal to feed anisolation amplifier.An isolated signal is recovered and conditioned to supplya current at the output, which is an exact representationof the primary voltage.

Features• Any kind of signal, DC, AC, pulsed and complex can be

measured • Galvanic isolation• Short dynamic response for a good frequency bandwidth • Fast response time • Small volume needed

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Motor Blower

3-Phase AC Motors Auxiliary InverterTo other 3-phase AC motors

Main Transformer

Battery

AxleBrush

AuxiliaryRectifier

Air Compressor

Locomotive Cooling Fans

Circuit BreakerPantograph

Main RectifierMain Inverter

DC Link

3-Phase AC Motors

M

CircuitBreaker

4 - Quadrant Controller DC - Link

CA

Uz

Inverter

Transformer

1c1a

2

2 5

1b

3c

3a

3b

6

6

4

4

4

V

U

Figure 1: Various parts of an AC electric locomotive

On-Board Applications

The electrical power is supplied tothe trains via the catenaries.So, depending on the country andalso to the applications (Subway,trolleybuses, high speed train,heavy traction…) the locomotivescan operate at different voltagelevels and under different systems.

1. Rolling Stock Heavy Traction

Heavy traction means high speed,or long distances, or heavily loadedcars (freight trains).For new lines, not part of an alreadyexisting network, AC voltage isoften the choice.Heavy traction rolling stocks aremade up of (figure 1):

countries with various electricalrailway catenary voltages, it hasbeen possible due to advances inmodern power electronics.Eurostar, for example, is able to runover four different voltages, 25 kV/AC/50 Hz, 3 kV DC, 1.5 kV DC and750 V DC.

The LV 100-Voltage series used atthis level allows the detection of thevoltage network, informing aboutthe country where is running thelocomotive (N°:1c in the figure 2).

To ensure the protection of thewhole system, the earth leakagecurrent to the wheels is alsomonitored thanks to special currenttransducers called CD seriesdedicated for that function (N°:1bin the figure 2). They are responsible

No contact and galvanically isolateddifferential measurement with alarge aperture for multiple primaryconductors result in safety-friendlytransducers and accuratemeasurement.

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- Main transformer,- Main rectifier,- DC link to make the connection

to the Main Inverter and AuxiliaryInverter,

- Main Inverter,- Auxiliary Inverter.

Main Transformer

Power from the catenaries routethrough the main circuit breakerbefore reaching the maintransformer. This is the first placewhere a current transducer can beadvantageous: The control of theinput current (N°1a in the figure 2).The LT 2005 & 4000 models bringthe necessary advantages for thatjob: a large aperture for cable pass-through of the primary conductoras well as high isolation voltage.

Although it is a complexundertaking to design a traincapable of operating in different

for measuring differential currentbetween 2 or 3 conductors anddetecting possible leakagebetween these conductors.It is also possible to accomplish thismeasurement by using 2 typicaltraction current transducers like theHAR 1000 or LT 2005 families.

Multi winding transformers convertthe catenary voltage to a voltagecompatible with the powerconverters.To get the best efficiency of theenergy provided by the network,accurate and reliable measurementis required. LEM proposes theadapted measurement tool“EM4T”, adapted to variousEuropean networks (please seesection dedicated to EM4T).One of the secondary windings ofthis transformer is used to build afour-quadrant controller.

Main Rectifier

This is generally made up by a fourquadrant controller to beconnected to the DC link.A four quadrant controller canregulate the flow of energy from theAC line to the DC link and from theDC link back to the AC line. It allowsto have the power, taken from thecatenaries, nearly close to themaximum theoretical value for agiven current and this over a largerange of speed and traction effort.In simple terms, this is an activerectifier.

This step is necessary for the 15kV/AC/16Hz 2/3 and 25 kV/AC/50Hz networks, in order todecrease the voltage level, and,also, to convert the voltage to a DCvalue, which has been defined asthe best compromise for thevoltage/current supplied to today’ssemiconductors. 2000 V is a

typical value at this stage of thevoltage transformation.The control of the input voltage (maintransformer output) is ensured by LV100-Voltage or CV 4-Voltagetransducers (N°:5 in the figure 2).

Figure 2: Where is the current and voltage measurement on the traction drive system ?

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Multiple options for a full modularity

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Various secondary connections

Various busbars

Various feet

LTC FAMILY

Mounting flexibility horizontal or vertical

350 A

500 A

1000 A

500 A

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UDC

UDC

M3

UDC

One current transducer may beused for the input currentmeasurement to control andprotect the four quadrant controller(N°:2 in the figure 2) such as modelsderived from LTC 1000 or LT 1005Series.

DC Link

This is the link between the mainrectifier output and the propulsioninverter input and the auxiliaryinverter.Its goal is to smooth the DC signal,limit the voltage (overloads), and/or filter the perturbations comingfrom the source (catenary/transformer) to the inverter or vice-versa.A voltage transducer derived fromthe LV 100-Voltage family can beused for these functions (there aremany models available for 2000 Vmeasurement which is a typicalvalue at this level) (N°:3c in thefigure 2). AV 100 Series transducerscan also be a solution if frequencyto follow is higher. The polarity onthe DC link is also a controlledparameter.

Current overloads and polarity arealso monitored by some currenttransducers to avoid powersemiconductor damage (N°:3a inthe figure 2): LT 1005, 2005, LTC1000 and LF 2005 families.

In the case of a direct DC voltagesupplied by the catenaries (notransformer, no rectif ier) (forsubways, or trolleybuses forexample, voltage line between 600to 900 V DC), the DC link could thenbe made up of a simple inductanceand some capacitors (LV 100-Voltage transducers range coversalso these values as well as the LV25-Voltage models) (N°:3c in thefigure 2).

As for measurement of differentialleakage currents at this level, theCD series transducers wouldsatisfy the requirement (N°:3b inthe figure 2).

Main Inverter or Drive PropulsionInverter

In the past, some other propulsionprinciples were running using seriesDC current motors. Initially, theadjustment of the motor speed andtorque was controlled by switchedseries resistors (figure 3).

The inverter is transforming the DCvoltage supplied by the DC link intoan AC voltage for a three phasesystem.The frequency and amplitude of theroot (base) signal can then beadjusted.The most used inverter today is the

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Years later, choppers appearedwith the use of the semiconductors(thyristors, then GTO thyristors orIGBT transistors). This lastpropulsion system is still often usedtoday for railway traction (figure 4).

Figure 4 : DC motor control perchopper

Today, however, the most popularway to propel the train is theasynchronous motor where thepower is supplied by inverters.

Indeed, asynchronous motorsbring advantages such ascompactness, robustness, lessexpensive for maintenance, andincreased productivity.(Synchronous motors are also oftenused for TGV propulsion forexample).

PWM (Pulse Width Modulation)inverter. This is made up of sixelectronic switches (initially GTOsfollowed by IGBTs) as representedin figure 5.

Figure 5 : AC motor control perPWM inverter

The switching frequency is normallyas high as possible.The motor voltage follows asinusoidal profi le and thefundamental frequency of thecurrent and the voltage supplied arefunctions of the required motorspeed. Depending on the requiredtorque, voltage and currentamplitudes fluctuate with thefrequency.To control these motor currentparameters, LTC currenttransducers located on each phaseof the asynchronous motor, fulfill all

Figure 3 : DC motor control per resistors adjustment

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Lines Accessories References1 Busbar KIT (busbar : 210 x 40 x 12 mm) 93.34.61.100.02 Busbar KIT (busbar : 185 x 40 x 8 mm) 93.34.61.102.03 Busbar KIT (busbar : 285 x 36 x 12 mm) 93.34.61.103.04 Busbar KIT (busbar : 260 x 36 x12 mm) 93.34.61.104.05 Busbar KIT (busbar : 195 x 36 x 10 mm) 93.34.61.105.06 Busbar KIT (busbar : 36 mm x 325 mm) 93.34.61.106.07 Busbar KIT (busbar : 185 x 40 x 10 mm) 93.34.61.107.08 Busbar KIT (busbar : 180 x 40 x 12 mm) 93.34.61.108.0

9 Busbar Fastening Kit (M5 x 25) dedicatedto busbars from lines 1 to 5 and lines 7, 8.

93.34.61.200.0

10 Busbar Fastening Kit (M5 X 40) dedicatedto busbar from line 6

93.34.61.201.0

11 Feet fixing Kit 93.34.63.100.0

*

*

*

*

*

***

∅

*

*

*

**

**

* including all the necessary for its mountingsuch as screws, washers, nuts, 2 clamps,busbar.

** as with * but without the busbar.*** including screws and 2 feet.

R.m.s. voltage value for partial discharge extinction depends on the busbar.Refer to the datasheet of the corresponding product.

R.m.s. voltage value for partial discharge extinction depends on the busbar.Refer to the datasheet of the corresponding product.

* including all the necessary for its mounting such as screws,washers, nuts, 2 clamps, busbar.

** as with * but without the busbar.*** including screws and 2 feet.

Accessories References

Busbar Kit * (busbar : 155 x 25 x 6 mm) 93.34.41.100.0Busbar Kit ** (busbar : 112 x 25 x 6 mm) 93.34.41.101.0Busbar Fastening Kit ** 93.34.41.200.0Feet fixing Kit *** 93.34.43.100.0

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LTC 600 & 1000 Transducer / Mechanical adaptation accessories

LTC 350 & 500 Transducer / Mechanical adaptation accessories

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the railway requirements for 350 to1000 A nominal currentmeasurements (N°:4 in the figure2): The LTC is modular, compact,designed for traction, manypossibil it ies of secondaryconnections, and fully approved fortraction.The LT 505, 1005, and 2005 seriesare also recognized for thisfunction, and have been used forseveral years in these applications.The higher the chopping frequency,the more sinusoidal is the currentwaveform.The choice of a Closed Loop Halleffect based transducer is justified:

- to get a fast response time (forprotection purpose),

- to “see” and support highfrequency signals of the current(ripple on the fundamental) fromthe high switching frequency ofthe inverter,

- and to achieve accurate controlof the speed.

Several propulsion motors can beconnected in parallel at the inverteroutput.Depending on the equipmentmanufacturer, some techniques arepossible to improve the voltagewaveform applied to the motor orto decrease the motor harmoniccurrents.The PWM inverter output phasevoltages can also be controlled withhelp from two voltage transducersderived from the LV 100-Voltage,AV 100-Voltage or CV-Voltagefamilies for speed control (N°:6 inthe figure 2).

Auxiliary Inverter

Auxiliary inverters are the systemssupplying other on-board loads.Although, not as popular, they areessential to the auxiliary loadsneeded for the propulsion and forthe passengers’ comfort.Depending on the catenary voltageson the applied loads at the output,on the constraints dictated by thecar itself (where it will be mounted :On the roof, into the floor…) or bythe application (environment)…, theelectronic schematics for the

auxiliary inverters are various, and,they use in all the cases all the lastinnovations of the power electronics.They have to bring the followingadvantages to the application:

- Compact,- Light weight,- High yield, low cost and low

maintenance,- High performance.

For DC power, auxiliary inverterscan be fed directly from thecatenaries and for AC power, theycan be connected to the maintransformer through a secondarywinding, but can also be connectedto the main or intermediate rectifierouput.By converting the voltage andcurrent under various waveforms(DC, AC, different frequencies,stable or variable frequency), theyhave the responsibility to supplysystems such as:

- Batteries: The DC voltageprovides charge to the batteryat different values depending onthe country and the tractionvehicle (24, 48, 72 or 110 Vbeing the most widely used).The batteries are used toprovide start-up current, foremergency lighting when the linesupply fails, or to supply powerto other auxiliary circuits.Charging and discharging of thebatteries are monitored byvoltage transducers.Depending on the accuracyneeded for this type ofmonitoring, various models areavailable.The CV 3 models are designedfor high accurate measurementthroughout their measuringranges followed by the AV 100and LV 100-Voltage models.

- Resistances and windings,- Motors: DC or even AC motors

operating under three phases380-400 V/50-60 Hz for carventilation, traction motors fansand traction compartment fans,blowers, pumps, compressors,etc.The start-up and shutdownof these motors areautomatically controlled by other

on-board systems but sti l lrequire current overload supportfrom the auxiliary inverter.

- Various electronics: AC single-phase power supplies controlpower, power plugs, lighting,etc. These voltages have to befiltered and stabilized since thecatenary voltages can fluctuate.The auxil iary inverter mustsustain any high transientovervoltages that may occur.

- Transformers…

Additionally, these systems supportthe operation of HVAC heating anddoors openers while having tooperate from several possiblevoltage networks for Europeancars.

The passenger’s comfort isrepresented more and more inthese systems and consequentlyincreases the overall energyrequirements. The auxil iaryinverters have to rationalize the bestenergy consumption by using thelatest power electronics technologyand take advantage of any possibleenergy savings.

For the previous mentionedreasons (protection and control),monitoring the DC or AC currentsand voltages at the input andoutput of the inverter is needed.This is also essential for successfulloop control. Again, depending onthe regulation accuracy required,the choices for voltage and currenttransducers are various.Furthermore, auxiliary inverters aresubject to cost pressures and oftenthe least expensive measuringsolutions are the final preferences.In this context, the bestcompromise of the price/performance ratio for the voltagemeasurement is the LV 25-Voltagefamily (200 V to 1200 V) and forcurrent measurements, modelsderived from the LTC and LACfamilies are typically the bestsolutions. All use the Closed LoopHall effect technology providinghigh bandwidth, overall accuracy at+ 25°C between 0.4 and 0.8 % ofnominal current (or voltage) and fastresponse time for current

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Copyright ALSTOM

LF FAMILY

1000 A

500 A

300 A

200 A

LAC 300-S

Very compact

packages

2000 A

SMA Technologie AG

Auxiliary InverterCopyright Bombardier

Mounting versatility

Several horizontal or vertical Mountings

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transducers (less than 1 µs @ 90% of Ipn).

If mounting constraints or overalldimensions restrictions are relevantthen other models can be used forthis function, such as the LA 205 /305 series or LT and LF 505 / 1005/ 2005-S families for example.However, if the price is the mainissue and if overall accuracy of 1% of Ipn at +25°C, a slightly longerresponse time (between 3 and10µs @ 90 % of Ipn) and a shorterbandwidth (10 to 50 kHz) areacceptable in the application then,the solution might be an Open LoopHall effect based currenttransducer: the HTA, HAR or HTCseries.

2. Rolling Stock Light RailCars (Trolleybus/Tramways)

In principle, there is no majordifference between the diagrams ofheavy traction and light rail tractionsystems.

Both are mainly propelled byasynchronous motors.

As for the heavy traction, thechopper technology is still oftenused to supply a series DC currenttraction motor.They operate mainly from DCvoltages supplied by the catenarieswith typical values such as: 600 V,750 V, 900 V, 1200 V or 1500 V atthe maximumThe main transformer and rectifierare then not needed.

Auxiliary inverters are also used, asfor the heavy traction, to generateeither three phase AC 380 V voltageor DC voltage (24, 48 V or more)for battery chargers. Both voltages(DC and AC three phase outputvoltages) can be isolated from theauxil iary inverter with anintermediate transformer.Trolleybuses as well as tramwaysare becoming more and moreimportant in cities to reduce thelocal air pollution. Trolleybuses arehowever more abundant thantramways, as they require less

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s significant infrastructure and also,as they are more convenient forsteep grades (where tramways arenot possible).

Often combined with a dieselengine (bi-mode), the rail networkcan be extended outside cities byusing the diesel mode. Also, thetrolleybuses and tramways, withtheir batteries charged via theauxiliary inverter or through wheelinertia or “Sup Cap,” ensure theirelectrical propulsion in placeswhere electrical networks are notpossible for architectural reasonsfor example: High flexibility.

3. Rolling Stock Underground(Subways)

At one time, subways propulsionsystems were based on resistorcontrol to control a series DCcurrent traction motor then,chopper control was progressivelyintroduced in the 70’s to reduce thepower losses and finally, combinedwith the regenerative braking toreduce overheating in tunnels andto save energy. Most of the recentdeliveries are now based oninverters controlling asynchronousmotors.

4. Rolling Stock Heavy TractionDiesel-Electric :

In the past, locomotives operatingwhere no electrical networks existhad only a couple of options:The diesel engine drives:

1. DC current generator,2. or, a three phase alternating-current generator.

Both scenarios need to supplypower to DC motors for thepropulsion.

The three phase alternating-currentgenerator must use a rectifier at theoutput to convert back to DC.

Current control from the generatorsis accomplished by a rheostat or agroup of contactors.Traction power is controlled byadjusting the rotational speedsetting of the diesel engine.DC voltages generated can be from400 to 1500 V with currents from500 A to 2500 A DC.

But as for all the other rolling stock,the trend is asynchronous motors.Today, we see that the share is 80% with AC and 20 % DC.This trend can also be justified bythe requirement to reduce the fuelconsumption.Indeed, asynchronous motorsprovide better yield than DC in thesame application.The whole electrical system issimilar to the one used for the heavytraction except that the initial ACpower is generated by the ACgenerator (alternator).The needs in current and voltagemeasurements are the same aspreviously detailed in the otherrolling stocks.

They operate mainly from DCvoltages supplied by the rails (thirdrail or 2 lateral rails) or by a catenary(for suburban lines) with typicalvalues: 600 V, 750 V up to 1500 Vat the maximum.Subway systems also use auxiliaryinverters for auxiliary functions suchas ventilation, air-conditioning,doors openers, etc., similar toheavy traction, trolleybuses andtramways.

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Auxiliary Inverter Copyright ALSTOM

Copyright ALSTOM

LT FAMILY

4000 A

500 A

1000 A

2000 A

Large current range capability up to 4000 A

LA 205 / 305 FAMILY

300 A200 A

Large choice of secondary

connections

Busbar or aperture

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High voltage distribution linesAC busbars

AC switchesor breakers

AC feedingcables

Transformer

DC swtichgears

To railIDC negative

Rectifier

To catenary or DC feeders

AC breaker Possibility to installtransducer

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Most of the trains are poweredelectrically. The necessary power toenergize the electrical motors forlocomotive propulsion is generatedat the railway substations.

Power substations convert the highvoltage provided by the utilitycompany’s distribution lines to thelow voltage (AC or DC) and supplyit with direct current needed tooperate railway vehicles.

Once generated, the voltage andcurrent are distributed to thelocomotives or rolling stocks via thecatenaries or rails (for urbanunderground railway for example).The voltages generated by thesubstations are various, due to thedifferent possible voltage networksexisting, according to the countrywhere the roll ing stocks arerunning.All the following voltage networksexist in Europe:

- 1.5 kV DC : in south of France,Netherlands…

- 3 kV DC : in Spain, Italia, Latvia,Slovenia, Estonia, Poland,Belgium,Croatia, Moldavia…representing about 30 % of theworldwide railway electrical lines,

- 15 kV / AC / 16.7 Hz: inGermany, Switzerland, Austria,Norway, Sweden...

- 25 kV/AC/50 Hz : Portugal,North of France, North of UK,Finland, Belarus, Yugoslavia,Bosnia & Herzegovina,Macedonia, Greece, Romania,Bulgaria, Hungary, Lithuania,Denmark…

- 3 kV DC and 25 kV/AC/50 Hz :Czech Republic, Slovakia,Ukraine, Russia…

- 750 V DC : UK…

Today, the trend is to have moreand more heavy rolling stockspowered with voltage lines underAC voltage.For the subways, trolleybuses, ortramways the voltage line is typicallybetween 600 to 900 V DC (600,750 and 900 Volt).

The substations then supply thesevarious voltages to the rollingstocks.The supplied voltage type (AC orDC) and levels make thesubstations different in theirbuilding.These substations are located asclose as possible to the tracks tomaintain a consistent power level.The number of substations all alongthe track is dependent on thepower supply requirement (subwayor high speed trains for example)and also of the traffic.

Generally, they are made up of(figure 6):

- AC switchgear,- Power transformers,- Power rectifiers,- DC switchgear.

Initially, the substation has an inputvoltage of 10.5 kV/AC/50 (60) Hzup to 66 kV/AC/50 (60)Hz, as anexample, and can convert it intodifferent levels of AC or DC voltagesdepending on the network supplyrequirement.

transformers may have additionalwindings for metering andprotection purposes.Some relays are protecting thetransformer and also contribute tothe rectifier protection.

Rectifiers

Most of the rectifiers are in 3-phasebridge connection.These rectifiers shall withstand a fullshort circuit until the opening of theAC breakers; this is rather commonin traction networks.It is not unusual to find currenttransducers measuring earthleakage current from the rectifier tothe rail (as represented in figure 6).

DC switchgear

DC switchgear is used to connectthe rectifier DC busbar and thecatenary (DC line).

Its aim is to open the circuit:

- During low impedance shortcircuits, the DC switchgear must

AC switchgear and Powertransformers

AC switchgear is similar to the onesinstalled in AC distribution stations.In a general way, the AC current

open within milliseconds toprevent overcurrent levelsexceeding breaking capacity.You will find current transducersaccurately measuring andmonitoring these short circuit

Figure 6: Typical Substation layout.

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HAR 1000-S Small size for 1000 A measured

Copyright ALSTOM

LV 100-VOLTAGE

Voltage Measurement

from 50 to 4200 V

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Vout (V)

+ Ipn

+ 10

- 10

- Ipn

HAZ xxxx-SB

Iout (mA)

+ Ipn

+ 20

- Ipn + 4

HAZ xxxx-SRI/SP1-

Vout (V)

+ Ipn

+ 10

- Ipn

HAZ xxxx-SRU

Iout (mA)

+ Ipn

+ 20

- 20

- Ipn

HAZ xxxx-SBI

Iout (mA)

+ Ipn

+ 20

- Ipn

+ 12

+ 4

HAZ xxxx-SBI/SP1 or SP2

Iout (mA)

+ Ipn

+ 20

- Ipn

HAZ xxxx-SRI

overcurrents while feeding relayswith defined trigger levels toopen the switchgear withoutdelay (as represented figure 6).

- During medium to highimpedance short circuits, theDC switchgear must openwithin a few hundredmill iseconds. Again, thecombination of the currenttransducer and relay will triggerthe switchgear to open,however, electronic analysis ofthe transducer ouput waveformwould allow furtherconsideration and decisionmaking (as represented figure 6).

Typical nominal currents in DCswitchgear range from 1000 to10000 A DC and voltages from 600to 3000 VDC.

Current transducers LT 4000-S/SP32, SP13, SP34, LT 4000-T/SP42, or HAZ 4000…20000models can measure and detectthese required levels and areespecially useful due to their largeapertures allowing wide primaryconductors as this is often the casein this kind of application.

The protection can also be ensuredby measuring the current at therectifier output using the same currenttransducers previously indicated., andrepresented in figure 6.

The voltage at the DC switchgearor the DC busbar (rectifier output)is often monitored to ensure theright voltage supplied to thecatenary (The LV 100-4000/SP2 isa possible voltage transducersolution as represented figure 6.

Many times, when DC circuitbreakers interrupt the circuit, areverse voltage is generated atabout 2 times higher than itsnominal value. This reverse voltageis generated by the arc splittingprocess. This arc is split into smallarcs in series within the arc chuteand each individual arc generatesa reverse voltage (20 to 25 V).These small arcs are containedbetween arc splitting plates. Thesum of all these individual small

voltages makes the total reversevoltage.After the interrupt (up to 80 to 150kA peak), the current thendecreases with a time constantL/R while the breaker reversevoltage is higher than the busbarDC voltage. The arc stops when thecurrent is at a zero value.The current transducers installedmust support these high over-currents (representing sometimes20 times their nominal value) andvoltages.

When bare or semi-isolatedbusbars are used for the primarycurrent feed into the substations,then the isolation for transducersis required (12 kVRMS/50 Hz/1 minas isolation test voltage as anexample).On the other hand, if the primaryconductor is isolated, this willtypically result in a large conductorrequiring current transducers witha large aperture. The LT 4000-Sand HAZ models provide theoversized aperture for large isolatedprimary conductors.

HAZ models are designed forvarious nominal currentmeasurements from 4000 up to20000 A and can supply variousoutput signals such as :

- +/- 10 Volt instantaneous:HAZ xxxxx-SB models,

- +/- 20 mA instantaneous:HAZ xxxxx-SBI models,

- + 4 to + 20 mA instantaneous:HAZ xxxxx-SBI/SP1 models,

- + 20 mA DC TRUE RMS:HAZ xxxxx-SRI models,

- + 4 to + 20 mA DC TRUE RMS:HAZ xxxxx-SRI/SP1 models,

- + 10 Volt DC TRUE RMS:HAZ xxxxx-SRU models.

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Signal Conditioning or Instantaneous Output

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4

True RMS0/4 - 20 mA0 - 10 V

OutputModel

Instantaneous DC True RMS

Voltage 0 - 10 Volt - SB- SB - SRU- SRU

Current 0 - 20 mA - SBI- SBI - SRI- SRI

Current 4 - 20 mA - SBI / SP1 or SP2- SBI / SP1 or SP2 - SRI / SP1- SRI / SP1

HAZ 4000 ... 20000 FAMILY

Measurement from 4000 A to 20000 ARMS

with the same compact size

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On-Board Applications:EM4T

With the liberalization and/orprivatization of some of the majorrail networks, a need arose to useboth the existing and planned railnetworks under construction to runtraction units across nationalboundaries.This gave train designers thedaunting task to develop multi-system locomotives to be used onmulti-networks.These prime movers would beneeded to operate on the differentsupply networks of borderingcountries along the route withoutrequiring an equipment exchangeat the regional or network supplyborder.Today, it is therefore technicallypossible to transfer people orgoods throughout Europe, fromNorway to Sicily for example,without any physical exchange ofthe locomotive (Picture 1).

Changes also in the EnergyMarkets in the form of deregulationand increased competition for largeuser contracts brought potentialbenefits for those wil l ing tonegotiate for their electrical tractionsupply requirements.This negotiation however requiresgreater knowledge and under-standing of the load profile of bulksupply points in one of the harshestelectrical environments – thetraction supply.Also to date, any financial benefitsto the train operating company ofregenerative braking - energy fedback to the supply network whena train is generating power underbraking conditions- was only ableto be determined based on un-metered experience.With the new energy meter fromLEM, for the first time, data for theprecise calculation of both suppliedand regenerated energy for billingpurposes can be accomplished onthe train, independently of theenergy supplier.

The first universal energy meter fortraction especially designed for on-board applications

With the EM4T energy meter, LEMhas introduced the first universalenergy meter for electric tractionunits with approval for billings insome countries (e.g. in Germanyfrom the Physikalisch-TechnischeBundesanstalt (PTB)). Thanks tothe advanced capability of theEM4T, it can be used both in newmulti-system locomotives nowunder construction and forretrofitting to all types of electricalrail vehicles already in operation.

EM4T - the load profile provider

EM4T is a single-phase energymeter and compliant to all relevantstandards for metering and on-board use. The energy values arecollected and stored in load profileswhich can be set and stored inintervals of 60 minutes to 1 minute.The measured data recordingscontain the following details:

- Date and time stamp- Events- Train identification numbers- Absolute energy values for

consumption and feedback ofactive and reactive energy

- Frequency of the network(50Hz, 16.7Hz or DC).

Data transmission for the meterreadout is possible via isolated,serial interfaces or via an opticalinterface according to EN 61107,mounted on the front panel. Anexternal time base (e.g. GPS) canbe used at one of the serialinterfaces for periodic timesynchronization. The memoryincorporated in the device enablesrecordings of the above data overa period typically of more than 300days (at a load profi le of 15minutes).

Meter accuracy of the EM4T

The meters are offered with astandard class accuracy of 1%.Since even small inaccuracies can

cause large errors in the case ofcalculating and invoicing such largeenergy quantities, EM4T is alsoavailable with improved accuracyoptions at class 0.5% and 0.2%(according to EN 62052-11).

Technical details

The input variables - current andvoltage - are connected to themeasuring circuits of the EM4T viadifferential inputs (Picture 2 and 3),designed for connection of allcurrent and voltage transducers/transformers currently available onthe market.Four (4) input channels areproposed for metering of both DCand AC signals of any existingtraction network (600 V DC to 3 kVDC, 15 kV AC 16.7 Hz, 25 kV AC50 Hz).The requirements for currentmeasurement at this level can bediverse. A clamp-on currenttransducer can be helpful in theapplication so as to not disrupt theinstallation. This is the case withLEM’s LA 200 or 500-SD models.Or, a large aperture transducer isappropriate when the primaryconductor is highly isolated tosupport the high level of voltage (15to 25 kV AC as nominal level):LEM’s LT 4000-S transducer familyis of this category.For the DC networks, thetransducer’s inherent isolationproperties are adequate.

Analog to Digital Sigma-Deltaconversion processors suppresshigh frequency disturbances in bothchannels, enhancing even furtherthe capacity to handle the oftenrapid supply transitions withintraction supplies.The 16-bit microprocessor readsthe sampled values and calculatesthe real energy in adjustableintervals (standard value = 15 min).The results are then saved in flashmemory (a special variant of anEEPROM).The voltage supply is via a DC/DCconverter, which in the standardversion, is designed for a nominalvoltage of 110 V DC (77 to 143 V).

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Siemens Train

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not electrified

electrified (DC) tracks

1.5 kV DC

3 kV DC

15 kV 16.7 Hz

25 kV 50 Hz

3 kV DC / 25 kV 50Hz

Picture 1 :European rail networks

EM4T

Energy meter forelectrical tractionunits railways

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A Di

A Du

A Di

A Du

AC

DC16 Bit-CPU

LCD, Tasten

RS232RS422

optisch EN61107

GSM-Modem

optional

Real-timeclock

Flash

RAM

DC/DC110 V

optional

CV 4-VOLTAGE FAMILY

High accuracy

Large bandwidth

1000 V to 4200 V

AV 100-VOLTAGE FAMILY

50 V to 2000 V

Short response time

One unique design

Picture 3: Block diagram of the LEM energy meter

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24 V (19.2 to 31.2 V) is alsoavailable as an option.

Standards and regulations

The EM4T has been designed tocomply with the followingstandards:

- EN 62052-11- EN 62053-21:

Class 1, 0.5, and 0.2 alternating-current watt-hour meters

- EN 50155:Electronic equipment used onrolling stock

- EN 50121-3-2:EMC part 3-2: Rolling stock -Apparatus

- EN 50125-1:Environmental conditions forequipment part 1: Equipment onboard rolling stock

- Final draft (Issue 5) of theCENELEC-TC9X working group11 (Railway Applications –Energy metering on-boardtrains)

- CENELEC prEN 50463: 2005

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LA 200 & 500-SD FAMILY

Clip-on current transducersEasy installations aroundcables and busbars

500 A

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15 kV / 16.7 Hz 25 kV / 50 Hz

Part of a high voltage frame of a multi-system locomotive with the positions needed forcurrent & voltage measurement

3 kV / DC 1.5 kV / DC

LA 200 & 500-SDLT 505-S/SP22LT 4000-S

CV 4-5000/SP3CV 4-6000/SP6LV 100-4000/SP2

LT 2005-S/SP2LT 4000-S/SP34LT 4000-T/SP40

200 A

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DC-LinkUDC

CircuitBreaker Interference

currentmeasurement

Short circuitdetection

Breakingcurrent

DCVoltage

MotorCurrent

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Applications

1. Interference FrequenciesDetection

Most of the trolleybuses, trams,subways and suburban networkswork with DC voltage (600 to 3000V DC).These networks are divided intodifferent isolated sections, eachpowered by different substations asseen previously.In addition to their normal DCvoltages provided, thesesubstations are supplying also asmall AC signal (of 42 and 50 Hz or60 or 100 Hz).When a train enters a given sectionof the track system, the wheelsshort the AC signals (through theaxle) and the “Track-Free-Signaling-System” protects thisarea with a red stop signal for theother trains.

By using PWM (Pulse WidthModulation) converters, the drivesystem of the trains also generatelow frequency signals which are fedback into the network.Due to these generatedinterference currents, the frequencyspectrum must be controlled andlimited to 10 A maximum throughinternal filters, because when afrequency of 42 Hz and/or 50-60-100 Hz is fed into the network, the“Track-Free-Signaling-System” willmeasure the signal and will openthis section of the track for the othertrains.For example, in an application, the25 Hz current generated and sentback to the DC supply can be 50times greater than the maximumlimit tolerated at 42 or 50 Hz (0.5A).

LEM RA family current transducershave been designed to detect ACcurrents up to 20 A peak, in adedicated bandwidth,superimposed on a DC current of2000 up to 3000 A DC with a givenaccuracy.A control system is then used to

monitor the output signal of theLEM transducer. If frequencies of42 Hz and/or 50 - 60 - 100 Hz arepresent, the system detects themand automated equipment stopsthe train.Normally, the PWM converters aredesigned so that the drive systemcannot generate these frequencies,but these may appear because ofdefects in the internal fi lter,malfunctioning of the pulsemodulation system of the drive, etc.The RA products are considered asimportant products in thisapplication as ensuring a safetyfunction.That is why the RA transducer isused in a redundant way, with 2pieces on the same busbar. Someadditional functions are oftenrequired in this kind of applicationand then added, like an built-in testwinding, part of the simulationsystem to check the overall safetychain before every start of the train.

DC component measurement issufficient and is performed by aClosed Loop Hall effect transducer.However, to achieve this level ofaccuracy, and withstand a highparasitic magnetic fieldenvironment, a special design isnecessary (LEM current transducerLB 2000-S/SP4 for example).Recall that the standard 2000 Atransducers have a DC offset errorof at least 2.5 to 3 A (Figure 8).

If the DC component control ismade on the primary of thetransformer where the supplyvoltage can be of 25 kVRMS AC, theAC current level will be much lowerand the low DC componentallowed will then require a moreprecise current measurementtechnology. Typically, Fluxgatetechnology can be used for thatrequirement but that means also atransducer with a large aperture asthe primary conductor will have to

Figure 7: Interference currentmeasurement on the DC link.

2. Main TransformerSaturation Detection

The measurement of a low DCcomponent in high AC currents canbe requested to control the currentsupplied by the main transformerpreviously to the driving converter.This DC component can saturatethe transformer and, as a result,hasto be limited or the faulty converterdisconnected.A 2000 ARMS transducer is requiredto measure both the AC currentand the DC component. For thatapplication, a 1 A accuracy for the

be isolated for the network voltage(25 kV for example) or thetransducer proposed will have tosupport this voltage level constraint.

3. Fault Detection

In underground DC traction powersupplies using a positive and anegative running rail, differentialcurrent detectors (CD differentialcurrent transducers) are needed todetect faults from either supply poleto earth (Figure 9).

Such faults would perturbingcurrents for the signaling system.In this application, primary currentsreaching up to 1200 A are

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LB 2000-S/SP4

4 Quadrant Controller

Inverter

TractionMotor

25 kV

M

200 Ohm

+ 420 V

- 210 V

100 Ohm

Substation

CD transducer

Earth fault = 3A

Earth fault = 6A

Figure 8: AC+DC measurement in transformer output of driving converter

CD FAMILY

RA FAMILY

LB 2000 FAMILY

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imbalance level of 1 A at a precisionof 0.1 A.In the same kind of undergroundvehicle, the heating circuits mustalso be controlled with differentialcurrent transducers. Currents ofapproximately 100 A are monitoredfor imbalance down to 100 mA witha maximum offset error of 15 mA.

4. MES Solutions

For the measurements of currents,voltages and powers, LEM candesign customer-tailored completesolutions.These are, for example, severaltransducers mounted on oneprinted circuit board and deliveredas a wired and tested set. Theseare the MES reference types.As an example, the MES 14 :

Copyright ALSTOM

Figure 9: Current balance detector for underground

24

Alternatorexcitation

MicroprocessorControl unit

Motorexcitation

Rectifier

Alternator

Engine WheelMotors

BreakingChopper

ResistorGrid

Inverter 1

Inverter 2

IDC

UDC

M

IM VM

M

IM VM

I

Rectifier

Alternator

Engine

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Applications

Mining Trucks Traction

Off-highway vehicles (trucks)operating in mining use highhorsepower diesel enginescombined with an electrical drivesystem to propel them efficientlywith electrical motors in harshenvironments such as large surfacemining.AC or DC drive systems can beused according to the motors used.The global systems for propulsionof these trucks are quite similar tothe ones used for the Diesel-Electric railway locomotives.LEM, based on its experience intraction applications, suppliescurrent and voltage transducers forcontrol in inverters, one of the majorsub-systems in truck drive systems.In open cast mining (surfacemining), the conditions are extremeleading to high constraints.The truck wheels are electricallymotorized, either DC or AC motors,driven by a specific drive (orinverter), as the ones used intraction applications to ensure thepropulsion locomotives.Electronic drives systems,compared to mechanical drives,provide lower operating costs andhigher haul productivity.The elimination of torqueconverters, drive shafts,transmissions, and differentials (allexhibiting high wearingcoefficients), reduces themaintenance, improves the truckslife time, reliability and finally overallcost.The motor torque and speedapplied to the wheels is controlledby the DC or AC drives by closelymonitoring the voltage and currentsupplied, avoiding then a gear box.This provides smooth application ofthe power to the wheels (this alsoreduces tire wear during wheelspinning and safe operation).

Wheel drive system with DC motors

mining) and provide the whole systemenhanced productivity by reducingmaintenance services (Brusheselimination, contactors decreasing…).

The use of power electronicsmakes the system simpler andmore reliable with increasedefficiency. And the improvedefficiency leads to less fuelconsumption.To simplify, the AC system is madeup of:- An alternator,- a rectifier,

As for the traction propulsion inrailway industry, the trend today isto use IGBT (GTO are also still used)based AC drive systems to controlAC motors (generally asynchronousmotors driving the wheels) for newlevels of performance. AC motorsare indeed less restricting (smaller,more robust, and, better suited forharsh environments such as surface

- a DC link,- one or several DC/AC drive

inverters,- a microprocessor control unit,- and motorized wheels

(asynchronous motors).The drive inverters are controlled bythe microprocessor control unit toconvert DC to AC power and tosupply the motorized wheels with

To simplify, the system is made upof:- An alternator,- a rectifier,- a microprocessor control unit,- and motorized wheels (DCmotors).

The microprocessor control unitmonitors the alternator and rectifier,and DC motorized wheels to deliveroptimal performance.The use of a microprocessorcontrol unit allows quickdiagnostics when defects occur.

Wheel drive system with AC motors

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HTA FAMILY

HTC FAMILY

250 A1000 A

500 A3000 A

One unique design

to cover their ranges

Copyright ALSTOM

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inverter with variable frequency, ACcurrent). This is the same conceptused for the drive propulsioninverters for locomotives in railwayindustry. All of the inverter outputparameters (current, voltage,frequency) are controlled by themicroprocessor control unit,adjusting if necessary, certainparameters at the inverter leadingto attain the required power for thecommanded torque and speed ofthe wheels.Current and voltage transducersare essential to monitor theseparameters. Nevertheless, due tothe harsh conditions of the appli-cation, the models used have to bewell adapted. Mining trucks areexposed to extreme dust, humidity,and temperature conditions allaround the world; therefore, thetransducer must be designed toperform optimally in thisenvironment.The result can be models issuedfrom the HTC series (500 to 3000A nominal), LT 505 - 1005 - 2005series for current measurement andfrom LV 100-Voltage family for vol-tage measurement. All transducersare potted to guaranteeexceptional protection againsthumidity and dust. Also, vibrationimmunity is important in such ap-plications. This explains the choiceof transducers adapted for tractionapplications, as they have alreadycomplied with high level vibrationconstraints originating from railwayapplications. Hence, all arequalified against the EN 50155standard for the environmentaltests.

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The rail industry operates in aphysically unique context.If there is a points failure, signalproblem or a fault with the rails, youcan’t just drive around the obstacle.More and more, people and goodsare to be moved. Existinginfrastructure must be exploitedmore efficiently.

The increasing separation ofinfrastructure and railwayundertakings responsibilities withinthe rail system, particularly inEurope, underlines the importanceof trackside and on-boardmonitoring. They serve to optimizethe capital and maintenance costof track equipment and rolling stockwhile ensuring satisfactorylevels of safety and operationalperformance.

A study about the reliability andmaintainabil ity of the railinfrastructure revealed the followingneeds :

- Introduction of conditionmonitoring methods,

- Optimization of the maintenanceplans,

- Guarantee of the safety level.

Monitoring systems arose fromthese needs expressed by thevarious maintenance contractors.One of the goals was to decreasetrain service interruptions due tofailures to improve the punctualityand to reduce potentially strongpenalties.Also, the availability of the railwaynetwork is becoming more andmore crucial.Existing infrastructure must beexploited more efficiently, that’s whymonitoring crucial track objects(points, crossing gates, signaling…)is an indispensable tool in thiscontext. Online monitoring makesit possible to take preventive action.Replacements take place beforeabnormalities lead to failures.Main functions of conditionmonitoring :

- Preventive maintenance,replacement to prevent failures,

- Maintenance processimprovement.

About 25 % of disturbancescausing trains delays are due to thepoint machines.

1. Points Machines (Picture 4) andCondition Monitoring

To measure the movement and theposition of the switch machines,you can use a:

- Position transducer,- Power transducer,- Pressure transducer,- Current and voltage transducers.

The curve of the motor current isshown every time the switch runs.This curve is compared with anideal situation (reference curve) ofthe motor current.A significant difference between thelast curve and the reference curvewill result in an alarm signal.Maintenance engineers can adjustthe alarm level (Figure 10) and it isalso possible to measure thevoltage to adjust the trigger if thereis a change in the voltage level.

As time elapses, changes in themachine footprint can indicatemechanical wear, lack oflubrication, points misalignment,and jamming within the pointsmechanism caused by ballast,electrical motor and winding failure.All indications result in an increasein total current absorbed.Any variation from the normal profilealso indicates the likelihood of otherdeveloping problems – wear, rust,debris, vandalism, etc.An early warning of machine failure,using current profile monitoringbefore problems or criticalbreakdown occur, is provided tosignal preventive maintenance.When necessary, the replacementof material (points motor forexample) is performed, withsupporting evidence, i.e. currentprofile records.The information is collected and

analyzed to predict a morepreventive maintenance time forsimilar equipment.Generally speaking, this optimizesthe efficiency of the railwaymaintenance staff, minimizes thetraffic disruption and keeps coststo an acceptable level.LEM has designed a dedicatedclip-on current transducer familycalled PCM (Points ConditionMonitoring), covering DC or ACcurrent measurements of 10, 20and 30 A nominal. To be mounteddirectly in the switch and withoutdisruption to existing cabling orconnections, the PCM currenttransducer is to be secured aroundthe conductor without any contact.This is one of the mainrequirements for retrofitapplications. Its mechanical designis also adapted to the harshenvironment along the tracks andwaterproof versions are available.

Most of the motors used for thepoints machines have been DCmotors but today, the trend is touse AC motors as they are morerobust, compact and lessexpensive on maintenance.The PCM-PR versions arededicated for these AC motors tocontrol the high speed trainswitches. They measure the AClow frequency currents (from 0.040to 1 kHz) exactly for the samereasons as for the DC motorspreviously and provide a 4-20 mADC output representing the trueRMS value of the measured signal.This kind of output signal iscompatible with PLCs that analyzethe data.

PCM products are designed for useby the railway maintenancecontractors as a retrofit tool for theactual infrastructure. Typically, thecontractors provide currentmeasurement without disruption tothe operating points machines.It is important not to interrupt thecurrent carrying conductors to thepoints motors as this would disruptthe safety chain mechanism.Hence, the PCM transducers aredesigned to allow uninterruptibleconnection and measurement by

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Clip-on design - Ideal for retrofit applications

PCM FAMILY

10 to 30 A

LTS FAMILY

LA 25-NP FAMILY

PCB mounted current transducers

6 - 15 - 25 A

0.25 to 25 A

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type of retrofit is a requirement bythe integrators and infrastructureowners.Of course, condition monitoringusing transducers may beintegrated into the initial design ofthe points machine system. If thisis the case, electrical currentinterruption is not a concern andtherefore other, more cost effective,current measurements areavailable. Being part of the originalelectronic assembly, PCB mountedcurrent transducers might be viablesolutions. LEM can offer the LTS6-15-25-NP or the LA 25-NP seriestransducers for this particularapplication.

2. Track Circuits (Picture 5) andCondition Monitoring

About 5 % of disturbances causingtrains delays are due to track circuitfailures.

The track circuit is a method ofindicating the presence of a trainon a given section of line.With relay-operated signals, theextend of the circuit typicallycorresponds to a signaling blocksection.

Figure 10: Typical current profile of a points DC Motor over the timePicture provided by courtesy of STRUKTON

Picture 4: Points Machine along the tracks.

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battery

insulated joints

rails

relay energized

signaling lights

train on section battery

rails short circuitedby the train wheels rails

relay de-energized

insulated joints

signaling lights

The source of current begins at oneend of the isolated rail section, thedriving current travels down the railto the end of the section where itthen energizes a relay, is redirectedto the other rail section and finally,returns to the power supply tocomplete the circuit. The energizedrelay prevents the signaling lightsto operate indicating that the railsection is free. (Figure 11).

today, with modern continuouswelded rails, it is more and moredifficult and less desirable to fitinsulated joints.Today, coded electrical impulsetrack circuits are installed.

Monitoring the actual track circuitcurrent flow, in lieu of the relay,would allow interpretation of thecurrent levels as an indication of

LEM transducers can work with ACor DC track circuits and areextensively used in the railwayindustry.The RCM 2A-VI/SP1 currenttransducer (0 to 2 A DC measuringrange) has been specificallydeveloped for measuring thecurrent in the vast number of relaysused within the rail network. Inaddition, this model design exhibitsthe non-contact measurementtechnique which is clearly arequirement for avoidinginterference of relay operation.For non-contact measurement, theCT series is also an option withnominal measurements of 100, 200or 400 mARMS and a large apertureof 11 mm diameter.Other current transducers are alsoavailable for this function, such asthe LTS 6-NP or LV 25-P (6 ARMS

and 10 mARMS nominal, respectively)capable of measuring AC or DCwaveforms with an integratedprimary conductor.

3. Crossing gates (Picture 6) andCondition Monitoring

About +/-15 % of disturbancescausing trains delays are due tocrossing gate failures.

In the USA, priority is on the levelcrossings (railroad crossings). Eachnew level crossing uses currentmeasurement for the motor, theincandescent lamps and bells.The current measured may be DCas well as AC.

Although the future is LED lamptechnology and thereby smallercurrents, current measurement issti l l necessary for conditionmonitoring.It is easily understood that themonitoring system must detect ifthe gate motor and signals areworking properly when there is anapproaching train. This is aquestion of safety and currentmeasurement provides thisknowledge.The motor current waveform canbe analyzed and compared with thetypical current profile during gateactivation.

Figure 11: Track circuit situation with no train on the track.

Figure 12: Track circuit situation with a train on the track

potential problems as well asknowing when a train is passing ornot. Typical current monitoringlevels are between 20 and 90 mAdepending of the resistance of theshort circuit.A current threshold detector can beused to report relay failure when thecircuit current changes but the relay

However, if there is a train on thesection, the current path is shortedthrough the wheels and axles,bypassing the relay, back to theother rail and returning to the powersupply. The relay is now de-energized and the signaling lightsare in operation indicating thepresence of a train (Figure 12).

For the system to work reliably, railjoints have to be electrically bondedwith a wire connecting the two railends. At each end of the section,the circuit has to be kept inisolation.Foreign objects (ice, leaves, etc.) onthe line can cause failure of thiscircuit resulting in an avoidance orcreation of an untimely short circuit.

This kind of circuit is typical for olderand existing installations, however

does not operate.By sensing the current in the lamps,the system can not only determineif the lamp filaments are intact andwired properly but, can also recordthe aspect (color) of the signal whena train passes a section of track.Consequently, an alarm can beissued if the driver passes a redsignal.Monitoring of the supply voltagesfor both the track circuit and signallamps will also highlight failures.

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RCM FAMILYDIN rail mounting

CT xx-P FAMILYPCB mounting

2 A0.1 / 0.2 / 0.4 A

Non-contact small current measurement

LV 25-P FAMILY

Current measurement of 10 mARMS

Picture 5: Tracks network

Picture 6: Signaling at a crossing gate

An excess of supplied current to themotor could signify a potentialfailure or problem such as the endof life of the motor or an obstaclein front of the gate.

Signal monitoring is a method toidentify if the lamps are workingfine. The current provided to theLED lamp cluster is monitored by ahighly accurate current transducer.A reduced LED current level wouldindicate that one or severalindividual LEDs have ruptured.There is a defined number ofallowable defective LEDs in a lampand this can be determined fromthe current level and then thedefective LEDs can be replaced toensure the minimum safety.Current transducers provide thisinformation.This early warning detection isuseful when scheduling routinemaintenance thereby reducing thecosts to schedule an unplannedrepair run.

Typical current consumption for alamp produced with several LEDsis 500 mA and 10 A for the gatemotor when lifting or lowering.

An inexpensive transducer solutionfor motor current monitoring is theLTS series with nominal currentmeasurements from 6 to 25 ARMS.For signal monitoring, the CT–Pseries meets the requirement with3 models covering accuratemeasurements from 100 mARMS upto 400 mARMS.These transducers providemeasurement with no contact withthe conductor. In this type of ap-plication, it is important not to addany new items in the existingsignaling circuit, that is to say, notto introduce a new potentialdisruption in the circuit. The non-contact measurement is a must asthey are considered safety items.

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s LEM’s Quality & Standards

Quality is demanded by everyoneand it is quite justified.The levels of quality required bycustomers are different dependingon the application as well as thestandards to comply with.This quality has to be reached butalso maintained and constantlyimproved for both products andservices. The different LEM designand production centers around theworld are either ISO TS 16949, ISO9001 and/or ISO 14001 certified.

Several quality tools have beenimplemented at LEM to assess andanalyze its performances. LEMutilizes this information to take thenecessary corrective actions toremain a responsive player in themarket.Among which the mostrepresentatives are:

DPT FMEA (Design, Process &Tool Failure Mode Effect Analysis)tool used preventively to:

- identify the risks and the rootcauses related to the product,the process or the machineryand,

- set up the corrective actions,

Control Plan: Description ofchecks and monitoring actionsexecuted along the productionprocess,

Cpk – R&R (Capabil ity forProcesses & MeasurementSystems):

- Cpk: Statistical tool used toevaluate the abil ity of aproduction procedure to remainstable and accurate within aspecified allowance range,

- R&R: Repeatabil ity andReproducibility: Tool to monitorthe accuracy of a measurementdevice within a pre-determinedallowance range,

QOS – 8D (Quality OperatingSystem – Eight Disciplines):

- 8D: Problem solving processused to identify and eliminate therecurrence of quality problems,

- QOS: System used to solveproblems,

IPQ (Interactive PurchaseQuestionnaire): Tool aimed atinvolving the supplier in the qualityof the purchased parts and spareparts.

In addition to these qualityprograms, and since 2002, LEMembraces Six Sigma as itsmethodology in pursuit of businessexcellence. The main goal is tocreate an environment in whichanything less than Six Sigma qualityis unacceptable.

LEM’s Standards

LEM traction transducers aredesigned and tested according torecognized worldwide standards.

The EN 50155 standard dedicatedto “Electronic Equipment used onRolling stock” in railwayapplications is our standard ofreference for electrical,environmental and mechanicalparameters.It guarantees the overallperformances of our products inrailway environments.All of the LEM traction products aredesigned according to the EN50155 standard.

CE marking is a guarantee that theproduct complies with theEuropean EMC directive 89/336/EEC and low voltage directive andtherefore warrants the electro-magnetic compatibil ity of thetransducers.

UL is used as a reference to definethe flammability of the materials(UL94V0) as well as the NFF 16101and 16102 standards for the fire/smoke materials classification.LEM is currently UL recognized formain models.You can consult the UL website toget the updated list of recognizedmodels at www.UL.com.

The individual datasheets preciselyspecify the applicable standards,approvals and recognitions forindividual products.

The EN 50124-1 (“Basicrequirements – Clearances andcreepage distances for all electricaland electronic equipment”)standard is used as reference todesign the creepage and clearancedistances for the transducersversus the needed insulation levels(rated insulation voltage) and theconditions of use.

The rated insulation voltage levelallowed by a transducer intendedto be used in an applicationclassified as being “Railway”, isdefined according to several criterialisted under the EN 50124-1standard. Some criteria aredependent on the transducer itselfwhen the others are linked to theapplication.These criteria are the following:

- Clearance distance (the shortestdistance in air between twoconductive parts),

- Creepage distance (the shortestdistance along the surface of theinsulating material between twoconductive parts),

- Pollution degree (applicationspecific - this is a way to classifythe micro-environmentalconditions having effect on theinsulation),

- Overvoltage category (applicationspecific - characterizes theexposure of the equipment toovervoltages),

- Comparative Tracking Index (CTIlinked to the kind of materialused for the insulated material)leading to a classification overdifferent Insulating Materialgroups,

- Simple (Basic) or Reinforcedisolation need.

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Non Competitive

Industry Average

World Class

Sigma Level

Defect Free

Defects Per Million

2

3

4

5

6

65%

93%

99.4%

99.976%

99.9997%

308,537

66,807

6,210

233

3.4

Key Six Sigma StatisticsCompany

Status

Source: Six Sigma Academy, Cambridge Management Consulting

LEM follows this thought processfor the transducer designs:Example: LTC 600-S, currenttransducer in an propulsion inverter

Conditions of use:

Creepage distance: 66.70 mm,Clearance distance: 45.90 mm,CTI: 600 V (group I),Overvoltage category: II,Pollution Degree: 3.

Basic or Single insulation:

According to EN 50124-1standard: With clearance distanceof 45.90 mm and PD3, UNi (Ratedimpulse voltage) = 30 kV.With UNi = 30 kV & OV II, the ratedinsulation voltage (AC or DC) called“UNm” can be from >= 6.5 up to <8.3 kV.With a creepage distance of 66.70mm and PD3 and CTI of 600 V(group I), it is allowed to have 12.5mm/kV, leading to a possible ratedinsulation voltage UNm of 5.336 kV.In conclusion, the possible ratedinsulation voltage, UNm, in theseconditions of use, is of 5.336 kV(the lowest value given by the bothresults from the creepage andclearance distances).

Reinforced insulation:

Let’s look for the reinforcedinsulation for the same creepageand clearance distances aspreviously defined:

When dimensioning reinforcedinsulation, from the clearancedistance point of view, the ratedimpulse voltage, UNi, shall be 160%of the rated impulse voltagerequired for basic insulation.The clearance distance of 45.90mm is already designed and then,we look for the reinforced insulationwith this distance.Reinforced UNi = 30 kV obtainedwith the clearance distance of45.90 mm.Basic UNi = Reinforced UNi / 1.6 =18.75 kV.Reinforced UNm: From >= 3.7 up to< 4.8 kV, according to the clearance

distance.From the creepage distance pointof view, when dimensioningreinforced insulation, the ratedinsulation voltage UNm shall be twotimes the rated insulation voltagerequired for the basic insulation.With a creepage distance of 66.70mm and PD3 and CTI of 600 V(group I), it is then allowed to have25 mm/kV (2 x 12.5) vs. 12.5 mm/kV previously (for basic insulation),leading to a possible reinforcedrated insulation voltage UNm of2.668 kV.

In conclusion, the possiblereinforced rated insulation voltageUNm, in these conditions of use, isof 2.668 kV (the lowest value givenby the both results from thecreepage and clearance distances).

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Response Time ( µs )

Nominal Voltage Measurement Range ( V )

LV 25-P Family LV 25-Voltage AV 100-Voltage CV 3-Voltage

Solutions for Voltage Measurement

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Acc

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+ 2

5 °C

( %

of V

PN

)

Response Time ( µs )

Nominal Voltage Measurement Range ( V )

LV 100 Family LV 100-Voltage LV 200-AW/2/Voltage CV 4-Voltage

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breaker

Main

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Auxiliary

inverter

Propul-

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inverterPower

measure-ment

Lighting / plugs

HVAC

SECONDARY SYSTEM

DoorsControl

Battery Charger

On-BoardEN

ERG

YV

OLT

AG

E

CU

RR

EN

T

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AS

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EN

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LT 505-S family

LT 1005-S family

LT 2005-S family

LT 4000-S family

LTC family

LAC 300-S

LA 205/305-S family

LF 205-S family

LF 305-S family

LF 505-S family

LF 1005-S family

LF 2005-S family

HTA family

HAR family

HTC family

LA 200..500 -SD family

HAZ family

LB family

CD family

RA family

CT -P family

LA 25-NP family

PCM family

RCM family

LTS family

LV 25-P family

LV 25-P family

LV 25-Voltage family

LV 100 family

LV 100-Voltage family

LV 200-AW/2/Voltage family

CV 3-Voltage family

CV 4-Voltage family

AV 100-Voltage family

EM4T

250-720 A

1000 A

1100-2000 A

4000-4400 A

350-1000 A

300 A

200-500 A

100-200 A

250-300 A

500 A

1000 A

2000 A

250-1000 A

1000 A

500-3000 A

200-500 A

4000-20000 A

2000 A

2 x 1000 A, 2 A differential

10-20 A AC Peak super-

posed on 1000 to 3000 A DC

0.1-0.4 A

0.25-25 A

10-30 A

2 A

6-25 A

0.01 A

10-1500 V

200-1200 V

100-4000 V

50-4200 V

100-6400 V

85-1400 V

1767-4200 V

50-2000 V

Points Relays SignalingSwitch-

gear

Packagerepresentedon page n°

Interfe-rence

measure-ment

Trackside SubstationProductSolution

NominalRange

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7 & 9

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Various options for secondary connections

Molex 5045/ASeries connector

JST VH SeriesConnector

Molex Mini-Fit, Jr 5566Series Connector

Molex 70543Series Connector

Threaded Studs, M4, M5, UNC...

...or Faston 6.30 x 0.80 orscrews......or the both, in the same time

M4, M5 inserts

LEMO Connectors

AMP Connectors

Burndy Connectors

Sub-D Connectors

Cables, Shielded Cables...

But also Wago, Phoenix, Souriau ... connectors36

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