HVI Track Circuits - RSSB Iss 2.pdfHVI Track Circuits. 2. RAILTRACK. Railway Group Approved Code of Practice GK/RC. 0756. Issue . Two. Date . December 1998. Page 2 . …

This document is the property ofRailtrack PLC. It shall not bereproduced in whole or in part withoutthe written permission of the Controller,Railway Group Standards,Railtrack PLC.

Published bySafety & Standards Directorate,Railtrack PLC,Floor DP01, Railtrack House,Euston Square,London NW1 2EE

© Copyright 1998 Railtrack PLC

Railway Group Approved Code of Practice

GK/RC0756Issue TwoDate December 1998

HVI Track Circuits

SynopsisThis Approved Code of Practicedetails the planning, installation,testing , maintenance and fault findingprocedures to ensure that the integrityof HVI Track Circuits is maintained atall times.

Approved by

Keith TurnerStandards Project Manager

Authorised by

Richard SpoorsController, Railway Group Standards

Withdrawn Document Uncontrolled When Printed

jtrousdale

Text Box

jtrousdale

Text Box

Signatures removed from electronic version

jtrousdale

Text Box

This page has been left blank intentionally


HVI Track Circuits

R A I L T R A C K 1


GK/RC0756Issue TwoDate December 1998Page 1 of 2

ContentsSection Description Page

Part AIssue record A1Distribution A1Health and Safety Responsibilities A1Supply A1

Part B1 Purpose B12 Scope B13 Glossary B14 Limitations B15 Introduction B16 Features B17 Principle of Operation B2

Part C Planning and Design1 Introduction C12 Uses and Limitations C13 Different Forms of HVI Track Circuit C24 Design Principles C65 Arrangements for a Network of Track Circuits C10

Part D Components and Installation1 Introduction D12 Bonding D23 Installation D2

Part E Instrumentation Description and Use1 Introduction E12 Test Equipment E1

Part F Testing and Commissioning1 Introduction F12 Cable Tests F13 Track Circuit Energisation F24 Drop Shunt Requirements F25 Limit Test F26 Electrical Stagger F27 Interference Tests F28 Table of Tests F2


HVI Track Circuits

2 R A I L T R A C K



Section Description Page

Part G Maintenance1 Introduction G12 Service B Tests G13 Track Circuit Maintenence Record Card G3

Part H Fault Finding1 Introduction H12 Sequential Testing H1

References Ref1


HVI Track Circuits

R A I L T R A C K B 1



Part AIssue Record

This Approved Code of Practice will be updated when necessary by distributionof a replacement Part A and such other parts as are amended.

Amended or additional parts of revised pages will be marked by a vertical blackline in the adjacent margin.

Part Issue Date CommentsPart A One August 1994 Original documentPart B One August 1994 Original documentPart C One August 1994 Original documentPart D One August 1994 Original documentPart E One August 1994 Original documentPart F One August 1994 Original documentPart G One August 1994 Original documentPart H One August 1994 Original documentReferences One August 1994 Original document

Part Issue Date CommentsPart A Two October 1998 Revised document.Part B Two October 1998 Revised document.Part C Two October 1998 Revised document.Part D Two October 1998 Revised document.Part E Two October 1998 Revised document.Part F Two October 1998 Revised document.Part G Two October 1998 Revised document.Part H Two October 1998 Revised document.References Two October 1998 Revised document.

DistributionControlled copies of this Approved Code of Practice should be made availableto all personnel who are responsible for the design, installation, testing,maintenance and faulting of HVI Track Circuits.

Health and SafetyResponsibilities

In issuing this Approved Code of Practice, Railtrack PLC makes no warranties,express or implied, that compliance with all or any Railway Group Standards orCodes of Practice is sufficient on its own to ensure safe systems of work oroperation. Each user is reminded of its own responsibilities to ensure healthand safety at work and its individual duties under health and safety legislation.

SupplyControlled and uncontrolled copies of this Approved Code of Practice may beobtained from the Industry Safety Liaison Dept, Safety and StandardsDirectorate, Railtrack PLC, Railtrack House DP01, Euston Square, London,NW1 2EE.




HVI Track Circuits



GK/RC0756Issue TwoDate December 1998Page B1 of 4

Part B1 Purpose

This Approved Code of Practice gives details of best practice in respect of GECAlsthom High Voltage Impulse track circuits in order to achieve the requirementsof GK/RT 0251.

2 ScopeThe contents of this Approved Code of Practice apply to all GEC Alsthom HighVoltage Impulse track circuits and is to be read in conjunction with GK/RC0752.

3 GlossaryThe definitions of terms used by Signal Engineers vary depending on the locationin which they were trained. A full list of terms is given in GK/RC0752, Part B.

4 LimitationsWhere job titles are used within this Approved Code of Practice to reflect theanticipated functional splits of responsibility relevant to technical competence,they should not be interpreted as actual job titles. The specific split ofresponsibility will be governed by a contractual framework, to which referenceshould be made.

Catalogue Numbers shown within this document are not directly controlled byRailtrack and as such, will not be maintained and kept up to date. Althoughevery effort has been made to ensure that these were correct at the time ofpublication, it is therefore recommended that your supplier is contacted and acheck is made with regard to the accuracy of these catalogue numbers prior touse.

Where references are made to other documents, a comprehensive list of thesewill be contained within the “Ref” section of this document. The informationappertaining to these references was correct as of Issue 13 of the RailtrackCatalogue of Railway Group Standards

5 IntroductionThe GEC–Alsthom High Voltage Impulse (HVI) track circuit is significantlydifferent from other types of track circuit. It has features that are very beneficialin its application under certain operating requirements. Its design is based onthe continental practice of centralised equipment rooms with remote linesidetransmission.

6 FeaturesThe HVI track circuit can only be used as a jointed track circuit and, dependenton the bonding configuration, can be used on electrified or non–electrified lines.The track circuit requires a power supply for the transmitter, but a power supplyis not required at the receiver/track relay. The high peak voltage used in theoperation of the track circuit will break through railhead contamination andenable the track circuit to be satisfactorily shunted by vehicles.

The HVI track circuit is immune to a.c., d.c., train borne electrical systems andexternal electrical systems. The performance of the track circuit can be affectedby neighbouring HVI track circuits. This mutual interference is prevented in thedesign process by the provision of electrical stagger between adjoining trackcircuits.

The track circuit settings are calculated during design, and are shown in thewiring diagrams. After the initial setting up, no further adjustments are required.

Inherent in its operation, the HVI track circuit has a very long drop-away timeand is categorised as Category C, requiring two slow-to-pick TPRs, or “extra


HVI Track Circuits

B 2 R A I L T R A C K



delay” data in SSI. Reference should be made to GK/RC0752 Part D forinterfacing details between adjacent track circuits.

7 Principle of Operation7.1 Rail Voltage WaveformThe HVI track circuit operates by applying a short high voltage impulse to therails at relatively long intervals. The asymmetric operating waveform has theshape of a high peak voltage (termed the positive polarity). A proportion of thisis reflected back as a reverse voltage of much lesser amplitude (termed thenegative polarity). The amplitude ratio of the polarities is typically 7:1, a typicalfeed end rail voltage waveform is shown in Figure B1.

X

7X

330ms 1.5ms 8ms

Figure B1

7.2 Feed EndA basic representation of how the equipment is arranged is shown in Figure B2.The waveform is generated by charging a capacitor to a high voltage and thendischarging it through a thyristor and matching transformer into the track. Theinductance of the feed and relay end transformers, together with that of the rails,causes the positive pulse to be followed by a negative undershoot. Thetransmitter is fed from a Power Supply Unit (PSU), which requires a 110V 50Wa.c. power supply, from which the current is constant whether the track circuit isoccupied or not. The design of the transmitter ensures that the waveform is notreflected back to the power supply.

7.3 Track EquipmentThe operating waveform requires connection to the rails through a tracktransformer. On electrified lines, the track transformer requires a protectiveresistance in series with the track winding to prevent the traction currentsaturating or damaging the winding. This resistance has scope for adjustment,but in the British application, adjustment is not required.

7.4 Receiver/Relay EndAt the receiver/relay end, the energy from the track transformer is rectified anddirectly drives the track relay, hence a power supply is not required at the relayend. The positive and negative parts of the waveform are rectified separatelyand applied to different windings on the relay. The relay has a magnetic circuitwhich ensures that it can only pickup if the applied voltages are in the correctratio (ie. the track waveform is correct).


HVI Track Circuits




PSU

Transmitter

TR

Receiver

TrackTransformers

Figure B2

7.5 Traction ImmunityHVI track circuits can only be applied in jointed form, and cannot be usedsuccessfully with impedance bonds currently installed on Railtrack’sinfrastructure, as they do not operate at a single frequency to which theimpedance bond can be set to resonate. Therefore, where they are used ind.c., a.c. or dual electrified areas, they are installed as single rail track circuits.

Note: Double rail HVI track circuits are currently under development and may beavailable for installation on Railtrack’s infrastructure in the future.

Parallel tracks are cross-bonded at regular intervals, so that the traction returncurrent from an individual train will have a number of different parallel paths backto the source (substation or feeder station). This minimises the impedance tothe traction supply and hence the volt drop, whilst it also limits the amount ofcurrent which can flow through an individual track circuit. However, under somecircumstances, the vast majority of current from an individual train will passthrough a single track circuit.

Where traction return current flows through a single rail HVI track circuit, themajority of the current will flow in the traction rail, resulting in a voltage dropalong its length. This voltage drop is proportional to the current, the track circuitlength and the impedance of the rail. With a train shunt applied toward the feedend of the track circuit, this voltage drop can be presented across the signal railand receiver end track transformer in series. Given the relatively low impedanceof the signal rail then the great majority of this voltage will be applied across thetrack transformer, creating corresponding currents in the relay coils.

Both transmitter and receiver are transformer coupled to the rails and theequipment is therefore isolated from d.c. traction currents in the track, or anyd.c. interference offset. Very high levels of d.c. current can however lead tosaturation of the track transformers and this therefore leads to a restriction onlength.

As described above (clause 7.1), the HVI track feed provides a series ofasymmetric pulses. At the receiver, the positive polarity and negative polarityvoltages are rectified separately and fed to different relay coils. A particular ratioof these rectified currents is required to energise the relay.

If the receiver is subjected to a.c. interference of sinusoidal form, the currentsrectified into each coil match each other, and the correct ratio will not beachieved. The HVI track circuit is therefore inherently immune to a.c. tractioncurrents.

However, large asymmetric transients within the traction current (from either a.c.or d.c. supplies), can occasionally create the correct ratio of currents in the relay


HVI Track Circuits

B 4 R A I L T R A C K



coils, leading to false energisation of the relay. In practice, the operate delay(800 ms minimum), due to the use of two slow-to-pick TPRs (to BR933) or “extradelay” SSI data, is sufficient to cope with transient interference, and wrong sidefailure of the track circuit is avoided. However, it is imperative that the lengthrestrictions and interface requirements contained within this Approved Code ofPractice are applied. These limits and time delays may require reassessment forthe introduction of new types of rolling stock.

Note: Tests have shown that NCO.RVT.600 receivers can be susceptible tohigh frequency (above 4 kHz) ringing of the a.c. electrification supply that iscaused by phase angle control systems used by some types of rolling stock (eg.Class 373/2). A temporary modification to fit a 1µF capacitor across the receiverinputs has been made to HVI track circuits on (and within 500m of) affected a.c.electrified lines, to provide protection until such time that a modification is madewithin the receiver unit itself. On fitting modified receivers, the external capacitorwill be removed.

To maintain satisfactory performance, the temporary modification requires twochanges to the track circuit:

• the receiver tapping should be changed to “3”;• the maximum permissible drop shunt is increased to 3.2Ω.

For details of the modification, see Special Inspection Notice GK/RT0405.

7.6 Electrical StaggerSince the waveform is considered to have positive and negative peaks,protection against IRJ failure can be obtained by ensuring that abutting trackcircuits have opposite polarities.


HVI Track Circuits

R A I L T R A C K C 1


GK/RC0756Issue TwoDate December 1998Page C1 of 11

Part CPlanning and Design

1 IntroductionThis Part describes the planning and design constraints that apply to HVI trackcircuits.

This Part should be read in conjunction with GK/RC0752, Part D, whichdescribes general planning and design criteria for track circuits.

2 Uses and LimitationsThe HVI track circuit is a jointed track circuit and can be used in S&C as well ason plain line. It is immune from d.c. and a.c. traction currents, although lengthrestrictions and interface delay constraints need to be applied to avoid wrongside failures due to large traction transients. The high peak voltage of the trackcircuit waveform, means that the HVI track circuit can be used with advantageon track with poor rail surfaces.

On a.c., d.c. and dual electrified lines, the HVI track circuit can only be used withbonding configuration SR, whereas on non-electrified lines, the track circuit maybe used with bonding configuration DRDS, DRSS or CR (see GK/RT0252 andGK/RC0752, Part D). Where required for electric traction purposes, common railthrough S&C can be considered as an acceptable cross bond between adjacenttracks.

Note: The length restrictions and interface delay constraints currently applied,may require reassessment for the introduction of new types of rolling stock.

Special considerations must be given to the installation of HVI track circuits whenused with SSI equipment to avoid interference (see Clause 4.1).

HVI track circuit components are relatively expensive (eg. when compared tosay d.c. track circuits) and its use has therefore been restricted to applicationswhere its functional capabilities are of benefit (eg. S&C areas in dual electrifiedareas and where poor rail surfaces exist).

2.1 Track Circuit Lengths

Line Maximum Minimum

Dual electrified lines 200m 18.3m

d.c. electrified lines 200m 18.3m

a.c. electrified lines 300m 18.3m

Non–electrified lines (CR bonding) 1200m 18.3mNon–electrified lines(DRDS or DRSS bonding) 300m 18.3m

Minimum track circuit length must be increased to 30m for line speeds over75 mph.

2.2 Track Circuit InterruptersTrack circuit interrupters shoud not be directly wired in series with HVI trackcircuits. Refer to GK/RT0252 and GK/RC0752.


HVI Track Circuits

C 2 R A I L T R A C K


GK/RC0756Issue TwoDate December 1998Page C 2 of 11

3 Different Forms ofHVI Track Circuit

There are three different forms of the HVI track circuit, all of which use thecommon equipment/circuitry as listed:

• HVI track circuit for d.c. electrified lines;• HVI track circuit for a.c. or dual electrified lines.;• HVI track circuit for non–electrified lines.


HVI Track Circuits




HVI Track Circuit on D.C. Electrified Lines

AP1 P1 D1 S1P2 D2 S2

P1 D1 S1P2 D2 S2

AP

AN

(1)

(2)

(1)

(2)(

A

B

C

HVI TracksideHousing

AA FEEDTRACK

TRANSFORMER

2c 2.5mm2(f)

Type C2

Resistor

ER2.2

Maximum 80mMaximum 500m

R

V+

V-

TV.TH1AP2

NCOEGT.600P

AA TX

C+16C-

NX110

BX110

3A

AA PSU

NCOEAT.115CA

(1)

(2)

(1)

(2)

A

B

C


AA RelayTrack

Transformer

ER2.2


V+

V-TV.TH1

AATR

AA RX

C+

C1-

C2-1 2 3 4

V1+ VV2+

ReceiverNCO

RVT.600

V1+V2+ V2-

V1-

RelayNCO

CV.TH2.404

Maximum 500m

)

R

(

)

))

)

)

)

)

(

(

))

))

2c 2.5mm2(f)

Type C2

2.5mm2(f)

Type C1

2.5mm2(f)

Type C1

Resistor1.15mm

2

Type A1

1.15mm2

Type A1

TO

Rails

a) Power supply NCO EAT.115CA

b) Transmitter NCO.EGT.600P.

c) Track transformers TV.TH1.

d) Resistors ER2.2.

e) Receiver NCO RVT.600

f) Relay NCO CV.TH2.404

Figure C1


HVI Track Circuits




3.2 HVI Track Circuit on A.C. and Dual Electrified Lines


P1 D1 S1P2 D2 S2

AP

AN

(1)

(2)

(1)

(2)(

A

B

C


AA FeedTrack

Transformer

Resistor

ER2.2


R

V+

V-

TV.TH1AP2

NCOEGT.600

AA TX

C+16C-

NX110

BX110

3A

AA PSU

NCOEAT.115CA

(1)

(2)

(1)

(2)

A

B

C


AA RelayTrack

Transformer

ER2.2


V+

V-TV.TH1

AATR

AA RX

C+

C1-

C2-1 2 3 4

V1+ VV2+

ReceiverNCO

RVT.600

V1+V2+ V2-V1-

RelayNCO

CV.TH2.404

Maximum 500m

)

R

(

)

))

)

)

)

)

(

(

))

))

2c 2.5mm2(f)

Type C2

2.5mm2(f)

Type C1

1.15mm2

Type A1

2c 2.5mm2(f)Type C2

2.5mm2(f)

Type C1

1.15mm2

Type A1

TO

Resistor

Rails


b) Track transformers TV.TH1.

c) Resistors ER2.2.

d) Receiver NCO RVT.600

e) Relay NCO CV.TH2.404

Figure C2


HVI Track Circuits




3.3 HVI Track Circuit on Non–electrified Lines


P1 D1 S1P2 D2 S2

AP

AN

(1)

(2)

(1)

(2)(

A

C


AA FeedTrack

Transformer


VA

VC

TV.TH.D2

AP2

NCOEGT.600

AA TX

C+16

C-

NX110

BX110

3A

AA PSU

NCOEAT.115CA

(1)

(2)

(1)

(2)


AA ReceiverTrack

Transformer


VA

VBTV.TH.D2

AATR

AA RX

C+

C1-

C2-1 2 3 4

V1+ VV2+

ReceiverNCO

RVT.600

V1+V2+ V2-

V1-

RelayNCO

CV.TH2.404

Maximum 500m

)

(

)

))

)

)

)

)

(

(

))

))

A

C

B

40 ohmsRESISTOR

RK.40

2c 2.5mm2(f)

Type C2

2c 2.5mm2(f)

Type C2

2.5mm2(f)

Type C1

2.5mm2(f)

Type C1

1.15mm2

Type A1

1.15mm2

Type A1

TO

Rails


b) Transmitter CO.EGT.600.

c) Track transformers TV.TH.D2

d) Resistors ER2.2.

e) Receiver NCO RVT.600

f) Relay NCO CV.TH2.404

Figure C3


HVI Track Circuits




4 Design Principles4.1 Housing of EquipmentIt is preferable that the track relay is installed at or about eye level, to assist inthe observation of its operating position.

To minimise interference, the HVI track circuit equipment should be placed onthe same side of the lineside apparatus housing as its track links. See Figure C4for a suggested arrangement.

HVI TC

Links

Receiver

HVI TC

Figure C4

The transmitter, receiver and relay units are mounted on plugboards fixed tomounting plates, which are rail mounted in standard lineside apparatus housingor equipment buildings. The mounting plates are two relays wide and 370mmlong and it is recommended that a maximum of five mounting plates are installedside by side.

The track transformers and, where required, resistors are mounted adjacent totheir corresponding rail connection. They should be mounted in a tracksidetransformer housing or, for several local transformers, in a standard linesideapparatus housing.

Where track transformers and resistors are mounted in HVI trackside housings,shielding of the terminals is not required. If they are housed in a standardlineside apparatus housing or equipment building then special shieldingarrangements are required. This can take the form of a transparent Perspexsheet, which is removable for maintenance purposes.

The nature of the oscillation produced by the HVI track circuit equipment iscapable of interfering with SSI equipment by means of radiated electromagneticinterference or by capacitive coupling between the cables. The potential forcausing right side failures exists thus reducing the reliability of the SSI data link.

It is therefore recommended that:

a) HVI track circuit transmitters, feed transformers, or cables connecting thetransmitter equipment should not be housed in the same lineside apparatushousing as Mark 1, or Mark 11 SSI Trackside Functional Modules.


HVI Track Circuits




b) Where Mark III (or later) SSI Trackside Functional Modules are housed in thesame lineside apparatus housing as HVI track circuit transmitters, feedtransformers, or cables connecting the transmitter equipment, thenarrangements must be put in place to prohibit their substitution by Mark I orMark II equipment.

c) SSI Interlockings and HVI track circuit equipment should not be installed inclose proximity to each other.

4.2 Lineside Apparatus Housing/Equipment Building WiringHVI track circuit internal wiring should be run separately from other equipmentwiring. This should be specified on the appropriate wiring diagrams.

All lineside apparatus housing wiring should be in standard 0.75mm² Type Acable, except the connections from the receiver and transmitter to theirassociated links which should be 1.15mm² Type A cable.

4.3 Track CablesThe track transformers are connected to the rails by track cables. So that theresistance of 0.7Ω is not exceeded, the maximum cable length is 80m. Thestandard arrangement is four single core, 2.5mm²(f) cables to GS/ES0872specification, terminated as shown in Figure C8.

4.4 Tail CablesThe power supply, transmitter, receiver and track relay are connected to thetrack transformers by tail cables. The maximum length of tail cable is 500m.

Each receiver should have its own tail cable, but, where advantageous, multipletransmitter feeds may be operated over a 2.5mm²(f), 2.5mm² or 1.5mm²multicore cable. Any multicore cable used for HVI track circuit transmissionshould not be used for any other purpose.

The terminations are as shown in 4.5.


HVI Track Circuits




4.5 Cable Terminations4.5.1 Transmitter End

Electrified Lines

TransmitterTerminal

TransformerInput

TransformerOutput

Rail

C+C-

AB

V+V-

+ve-ve

Figure C5

Non–electrified Lines

TransmitterTerminal

TransformerInput

TransformerOutput

Rail

C+

C-

A(via RK40-0-0.7)

C

VA

VC

+ve

-ve

Figure C6

4.5.2 Receiver End

Electrified Lines

ReceiverTerminal

TransformerInput

TransformerOutput

Rail

C+C1-

AC

V+V-

+ve-ve

Figure C7

Figure C8


HVI Track Circuits




4.6 Transmitter SettingsDesigners should know the distance between the transmitter and the tracktransformer to an accuracy of 25m. This information is required to set the loopresistance of the tail cables and transmitter to approximately 20Ω using theadjustment terminals of the transmitter. These settings are calculated at thedesign stage, and are shown in Figure C9.

Tail CableLength (m)

Cable Resistances

2.5mm² 2.5mm² (f) 1.5mm²

TransmitterTerminalStraps

1-120121-240241-360361-500

2.0Ω3.6Ω5.4Ω7.6Ω

2.0Ω4.0Ω6.0Ω8.2Ω

3.0Ω6.0Ω8.8Ω12.2Ω

C+ to 6C+ to 5

C+ to 5 & 2 to 3C+ to 6 & 3 to 4

Figure C9

Note: The transmitter terminal straps are not intended for on–site adjustment.

4.7 Receiver SettingsFor track circuits on electrified lines the receiver should have terminals V and 2linked together after initial resetting.

For track circuits on non–electrified lines, the receiver should have terminals Vand 1 linked together.

4.8 Unit WiringThe wiring diagrams should show all inter–unit connections as shown in FigureC1, Figure C2 or Figure C3.

4.9 Fuses, Surge Arresters and EarthingThe power supply for the transmitter should be fused with a 3A fuse to BS 714or Def. Stan 59-96 size 0. For all mains power calculations, the maximum powerconsumption is 50W at 110V a.c.

The track circuit equipment is isolated from the rails by the track transformers asshown in Figure C1, Figure C2 and Figure C3. Since the track transformercan withstand any traction interference apart from a full traction short circuitcurrent and as there is no viable fuse available which will break this current intime to protect the equipment, fuses are not fitted in the track leads. Anydamage will, therefore, be limited to the track transformer.

Because of the high voltages present, the track cable disconnection links inlineside apparatus housing/equipment buildings should be enclosed fuse holdersfitted with links in place of fuses. Surge arresters are not required.

The high voltages on the HVI track circuit can cause a reflexive shock, but donot directly endanger health. Therefore, earthing arrangements are notrequired.


HVI Track Circuits

C 1 0 R A I L T R A C K



5 Arrangements fora Network of

Track Circuits5.1 Electrical StaggerThe HVI track circuit should be arranged in order to provide a change of polarityacross IRJs abutting adjacent HVI track circuits, the intent being that IRJ failurewill prevent false operation with the track circuit occupied. The only permittedexception to this rule is at IRJs where two feed ends abut.

5.2 Mutual InterferenceOn common rail networks (which include single–rail traction return sections onelectrified lines), to prevent a residual polarity building up on the common rail,there should be, as near as possible, an equal number of +ve and -ve feeds tothe common rail. Although this should generally occur due to the electricalstagger, it should be checked.

5.3 Adjoining Other Types of Track CircuitThe HVI track circuit has the potential to falsely energise d.c. track circuits(including diode track circuits, but not a.c. immune types) or non-frequencyselective a.c. track circuits (e.g. quick release track circuits). Therefore, the onlypermissible interface with non a.c. immune d.c. track circuits or non-frequencyselective a.c. track circuits is at their feed end. As the relay of the diode trackcircuit is at its feed end, then the permitted interface is at the diode end only.

Since this condition precludes intermediate interfaces between HVI track circuitsand these types of track circuits, interfaces in S&C layouts are not permitted.

5.4 Operating CategoriesThe HVI track circuit is category C (see GK/RC0752, Part D).


HVI Track Circuits

R A I L T R A C K C 1 1



5.5 Contact UsageThe contacts used in the track relay type NCO CV.TH2.404 are shown in FigureC10.

FRONT BACKCONTACTS CONTACTSM1 T1 M2 R2M3 T3 M4 R4M5 T5 M6 R6M7 T7 M8 R8

Track Relay(Rear View)

T1 T3

M1 M3

R2 R4

T5 T7

M5 M7

R6 R8

M

V2- V2+

T1 M1

M3 T3

B

N

TR

TR

M6 M8M2 M4

V1- V1+

Figure C10




HVI Track Circuits

R A I L T R A C K D 1


GK/RC0756Issue TwoDate December 1998Page D1 of 4

Part DComponents and Installation

1 IntroductionThe following is a list of all equipment and catalogue numbers. Unless otherwisestated, one of each item is required for each track circuit. The installationguidelines are outlined in this Part:

Note: The Catalogue Numbers shown within this document are not directlycontrolled by Railtrack and as such, will not be maintained and kept up to date.Although every effort has been made to ensure that these were correct at thetime of publication, it is therefore recommended that your supplier is contactedand a check is made with regard to the accuracy of these catalogue numbersprior to use.

Description Catalogue No.PSU/transmitter end mounting plate, with : 86/43597package of screws and contact labels(BRS-SM 440 T2)Relay/receiver end mounting plate, with : 86/43598package of screws and contact labels(BRS-SM 440 T3)Plugboard type NS1.PFC12 for use with : 86/43909NS1 style racking (7 per track circuit).Crimped Connectors - Faston type 110, : 86/43912gold plated, bag of 1000Crimp Tool, AMP part No 47386-4 : 39/08126

Key, occupation/securing : 88/23324Power supply unit (NCO.EAT.115.CA) : 86/43900

Transmitter for d.c. electrified lines only : 86/43907(NCO.EGT.600P)Transmitter for electrified or : 86/43921non–electrified lines (NCO.EGT.600)Receiver (NCO.RVT.600) : 86/43901Track Relay (NCO.CV.TH.2.404) : 86/43902Track transformer for non–electrified lines : 86/43903(TV.TH.D2) (2 per track circuit)Track transformer for electrified lines : 86/43904(TV.TH1) (2 per track circuit)Resistor for electrified lines : 86/43905(ER-2.2) (2 per track circuit)Resistor for non–electrified lines : 86/43920(RK-40-0-0.7) (2 per track circuit)Holder, Fuse 32A 660V : 86/13053front connecting (4 per track circuit)Link, Solid copper for Fuse Holder 86/13053 : 86/13065(4 per track circuit)Transformer box : 86/43922(c/w mounting brackets)


HVI Track Circuits

D 2 R A I L T R A C K


GK/RC0756Issue TwoDate December 1998Page D 2 of 4

2 BondingThe bonding arrangements for the HVI track circuit are detailed in GK/RT0252and GK/RC0752, Part E.

3 Installation3.1 Mounting PlatesThe plugboards are installed on vertical mounting plates, as shown in Figure D1.The mounting plates attach directly to the standard racking to BRS-SM 440sheet G1. The standard racking should be placed 342mm apart (at variancewith BRS-SM 440) to accommodate the mounting plates.

Track RelayLabel

TransmitterLabel

Power SupplyLabel

ReceiverLabel

TransmitterPlate

ReceiverPlate

Figure D1


HVI Track Circuits

R A I L T R A C K D 3


GK/RC0756Issue TwoDate December 1998Page D3 of 4

3.2 Equipment MountingThe equipment units are installed on plugboards, which aid replacement ofdefective units without wiring disconnection. Coding pins, similar to those usedon BR 930 style relays, are used to ensure that the correct units are installed.The equipment units are secured by a lug which is turned from the front with thetriangular key. The equipment will not operate correctly unless the lockingmechanism is fully turned.

In equipment buildings and lineside apparatus housings, cables to and fromtransmitters, receivers and relays should not be run parallel to cables carryingcircuits for other electronic equipment, such as reed, TI.21 and SSI. Thisrestriction does not apply to the power supply cables of the transmitter PSU.

3.3 Plugboards and ConnectorsThe plugboards used are different from standard miniature relay plugboards. Upto three are used with some plug–in units.

The wiring does not connect directly to the contact springs but is attached usingminiature automobile Faston connectors. Each connector takes one wire buteach contact position can accommodate two connectors.

The connectors are used with 1.15mm² and 0.75mm² Type A cable and shouldbe crimped with the correct tool.

3.4 Transformer Equipment and HousingsThe track transformers should be positioned within 80m of their rail termination toavoid excessive circuit resistance. They are usually mounted in small tracksidehousings, the intended layout of equipment is shown in Figure D2. If mounted instandard lineside apparatus housings, special terminal shielding arrangementsare required for safety.

With reference to Part F, the trackside transformer housing constitutes adisconnection point and no other lineside disconnection point is required.

There should be two trackside housings per track circuit, but each one can beshared with an adjacent HVI track circuit.

In the trackside housing, it is good practice to install the type ER2.2 resistorupside down to aid wiring and to avoid excessive strain on the wires. It is notcritical which way around the blue and brown wires are connected to terminals Rand V- of the transformer. It is important to insulate the uncut green wire, as thisis unused.

TransformerTV.TH.02

TransformerTV.TH.02

ResistorRK 40.0.0.7

ResistorRK 40.0.0.7

TransformerTV. TH1

TransformerTV. TH1

Twin ResistorBlock ER 2.2

Figure D2


HVI Track Circuits

D 4 R A I L T R A C K


GK/RC0756Issue TwoDate December 1998Page D 4 of 4

3.5 Track CablesThe track transformers are connected to the rails by track cables. So that theresistance of 0.7Ω is not exceeded, the maximum cable length from thetransformer to the rails is 80m. The standard arrangement is four single core,

2.5mm2(f) Type C1 cables to specification GS/ES 0872.

The track cables are installed and terminated as indicated on the wiringdiagrams.

3.6 Tail CablesThe tail cables should not exceed 500m in length. Formal design changes will berequired if the installed length is not as shown in the lineside apparatus housingwiring diagrams to a tolerance of ±25m. The transmitter and receiver wiring isconnected to the tail cables on shrouded terminals. The tail cables may be runin the same external cable route as other signalling circuits.

Note: As there are high voltages on the tail cable circuits, there should be nobare terminals on these circuits in equipment buildings or lineside apparatushousings. Therefore, the wiring from the outgoing/incoming links to thetransmitter/receiver should be unbroken by terminal strips. If an intermediatetermination is required, it should have shrouded terminals, as above, and a highvoltage warning label.

The tail cables are installed and terminated as indicated on the wiring diagrams.

3.7 Safety LabellingDue to the high voltage impulses present on HVI track circuits, it is necessary toinstall warning labels inside the lineside apparatus housing/equipment buildingfor the purposes of staff safety.

The warning labels depict a yellow triangle with lightning flash, as described inGK/RC0752, Part E, and are installed on:

• lineside apparatus housing / equipment building rack.

• Transmitter end racking;

• Power supply unit Transmitter;

• Outgoing links;

• Track transformer housing;

• Track transformer;

• Incoming links Receiver;

• Track relay;

• Receiver end racking;

• Shrouded terminals in lineside apparatus housings.


HVI Track Circuits

R A I L T R A C K E 1


GK/RC0756Issue TwoDate December 1998Page E1 of 1

Part EInstrumentation Description and Use

1 IntroductionThis Part describes the instrument particular to HVI track circuits. Details ofmore general test equipment are contained in GK/RT0752.

2 Test EquipmentAn adaptor integrator is required for the measurement of the transmitted pulses.It uses capacitors to store the peak voltages of one polarity only and convertsthe waveform into a voltage level which may be measured by a digital volt meter(DVM) on the d.c. auto–range. To measure the opposite polarity, the testprobes should be reversed. It is connected as shown in Figure E1.

Description Catalogue No.Adaptor Integrator (French Design) : 86/43906.High impedance voltmeter with shrouded probes : 40/56003.

dc auto

Optional 2M2 ShuntFor Faster Meter Discharge

No Other TerminalsTo Be Used

AdaptorIntegrator

DVM

Rails

ITE

Figure E1




HVI Track Circuits

R A I L T R A C K F 1


GK/RC0756Issue TwoDate December 1998Page F1 of 3

Part FTesting and Commissioning

1 IntroductionThis part should be read in conjunction with the general information inGK/RC0752 Part G. Only special instructions for HVI track circuits are coveredin this Part. The table of tests (Figure F1) should be referred to for theapplication of the tests and the results required.

The test results should be recorded on the Track Circuit Maintenance RecordCard (Part G).

The Track Circuit Test Certificate should also be completed. There are someoperations which are not required for the HVI track circuit; a dash should be putnext to these tests.

Note: Transmitters and power supply units should not be plugged in orunplugged, or straps changed whilst they are powered up.

2 Cable TestsThe standard cable tests, as stated in GK/RH0730,GK/RH0740 andGK/RC0241, are now carried out. It should be noted that the HVI track circuittail cables are not exempt from these tests, whereas the track cables areexempt.

All cable problems should be found by the cable tests. However, if they are notfound, the subsequent testing will highlight the faults, examples of which areshown below.

2.1 Crossed Connections between Transmitter and ReceiverIf any of the cables between the transmitter and receiver ends are crossed, therelay will not operate correctly. On energisation, the relay may pick up briefly butwould then drop.

The effect of such a cross is a reduction in the rail voltage (Test T4) when alllinks are inserted, however Test T5 will not show this fault condition. Typically,with track circuits of up to 600m a reduction in voltage of 25% at the feed endand 50% at the relay end will be found.

Note: Without the receiver in circuit, this voltage will still be as expected.

If the cross is at the feed end, the rail polarity will be the wrong way round. Thevoltage on the relay will also be reversed, with the higher voltage now on coil V1.Due to impedance mismatching at the relay coils, the lower voltage, now on V2,may be significantly reduced from that expected.

2.2 Crossed Connections between Receiver and RelayIf the wires between the receiver and the relay are crossed, the relay will notoperate correctly. On energisation, the relay may pick up briefly but would thendrop. The higher voltage would again be on V1, with the same symptoms asabove.

If the wiring to one winding is crossed, the voltages (Test T3) will appear asexpected, but reversed, and the relay will not operate correctly. The railvoltages (Test T4) should not be impaired.


HVI Track Circuits

F 2 R A I L T R A C K



3 Track CircuitEnergisation

Insert relay end, then the feed end links.

Insert BX supply fuse to energise the transmitter.

Check that the relay energises.

Verify correct polarities to rail and confirm with the bonding plan.

Verify the +ve polarity is connected to V+ or VA of both transformers.

Measure:-

• The supply voltage & current (Test T6);

• The transmitter power (Test T7);

• The feed end voltage (Test T8);

• The pulse rate (Test T9);

• The relay voltage (Test T3);

• The relay end voltage (Test T4);

• The load capability (Test T5);

4 Drop ShuntRequirements

For the general drop shunt (0.5Ω) procedures see GK/RC0752 Part F. Thedrop shunt tolerances are given in Tests T1 and T2.

The track relay will pulse before it drops away. It will then remain moving on itsback contacts until the track circuit is shunted.

• Measure the drop shunt at the relay end track transformer (Test T1).• Measure the drop shunt at the rails at the relay end (Test T2).

5 Limit TestThe minimum drop shunt should be applied to the extremities of the track circuit.Details are contained in GK/RC0753 Part G.

6 Electrical StaggerWhere electrical stagger is required, verify the polarities of the rail voltages oneither side of the IRJ, using the adaptor integrator.

7 Interference TestsThe only source of external interference will come from other HVI track circuitequipment. The interference tests require the track circuit under test to be de–energised and all adjacent track circuits to be energised.

• Measure the unshunted interference (Test T10).• Measure the shunted interference (Test T11).

8 Table of TestsThe Figure F1 lists details of all tests specific to HVI track circuits.


HVI Track Circuits

R A I L T R A C K F 3



Test Description ElectrifiedLines

Non–electrifiedLines

T1 Drop Shunt Test at relay end track transformer track terminals. Min 1ΩMax 3Ω

Min 0.5ΩMax 2.5Ω

T2 Drop Shunt Test at relay end rails. Min 1ΩMax 3Ω

Min 0.5ΩMax 2.5Ω

T3 Relay Voltage Test at track relay plugboard contacts, using DVM on d.c.manual range.There will be a fluctuation in the reading.

V1+ to V1-Min 20VMax 50V




T4 Relay Voltage Test at track relay end track transformer track terminals,using adaptor integrator with DVM on auto range.The ratio of the +ve to -ve polarity should be in the range:

Min 5 : 1Max 10 : 1

V+ to V-Min 50VMax 150V

Min 8VMax 22V

VA to VBMin 20VMax 120V

Min 2VMax 12V

T5 Load Test at relay end track transformer track terminals with 0.5Ω shuntacross the track terminals, using adaptor integrator.

V+ to V-Min 10V

VA to VBMin 6V

T6 Supply Test voltage and current of mains, under full working load. Min 95VMax 121V

Min 0.3AMax 0.5A

Min 95VMax 121V

Min 0.3AMax 0.5A

T7 Test to be completed within 2 minutes

Transmitter Power Test between terminals 1 (+ve) & 3 (-ve) of thetransmitter, with a short circuit between terminals C- and 6 of thetransmitter.If any terminals 1 to 6 are strapped together, temporarilydisconnect at one end. If any terminal other than 6 is connected to theoutgoing links, remove the links.Use adaptor integrator.

Min 120V Min 120V

T8 Feed End Voltage Test at the feed end track transformer track terminals,using integrator adaptor.The ratio of the +ve to -ve polarity should be in the range:

Min 5 : 1Max 10 : 1

V+ to V-Min 50VMax 150V

Min 8VMax 22V

VA to VCMin 20VMax 120V

Min 2VMax 12V

T9 Pulse Rate Test measured by touching the rear casing of feed end tracktransformer.

Number of pulses in 7 seconds: Min 15Max 30

Min 15Max 30

T10 Unshunted External Interference Test measured bydisconnecting the PSU fuses.Voltage at track relay terminals, using a DVM on d.c. manual range.

V2+ to V2-

Max 10V

V2+ to V2-

Max 6V

T11 Shunted External Interference Test measured bydisconnecting the PSU fuses and connecting a short circuit across thefeed end transformer V+ V-.Voltage at track relay terminals, using a DVM on d.c. manual range.

V2+ to V2-

Max 7V

V2+ to V2-

Max 7V

Figure F1




HVI Track Circuits

R A I L T R A C K G 1


GK/RC0756Issue TwoDate December 1998Page G1 of 4

Part GMaintenance

1 IntroductionThis Part details the requirements for maintenance of HVI track circuitequipment. The general physical examination of the track circuit is the same asfor other types of track circuit and can be found in GK/RC0752 Part H.

No adjustments can be made to the HVI track circuit during maintenance visits.It does, however, have components whose performance can be expected tochange. The performance of these components is tested during periodicmaintenance to ensure that they remain within levels which will avoid failure ofthe track circuit.

This section gives more details of the maintenance requirements of the HVI trackcircuit, how measurements are made and what conclusions may be drawn fromthe results. The conclusions may be used to take immediate remedial action toprevent a developing failure. The values should be noted on the Track CircuitMaintenance Record Card, an example of which is shown in Figure G1 andFigure G2.

Note: Transmitters and power supply units must not be plugged in orunplugged, or straps changed whilst they are powered up.

2 Service B TestsService B comprises the following tests (see Part F and GK/RC0752, Part H):

• T1 Drop Shunt Test;

• T3 Track Relay Voltage;

• T4 Relay End Track Transformer Voltage;

• T5 Current at Relay End Track Transformer;

See Figure F1 for maximum and minimum values of tests.

2.1 Test T1: Drop Shunt TestThe drop shunt test is taken on the relay end track transformer track terminals.

2.2 Test T3: Track Relay VoltageThe track relay voltages V1 and V2 will indicate the correct functioning of thereceiver, and will vary inversely proportional to the drop shunt value (ie. as thetrack voltage rises the drop shunt will fall).

Track relay voltages which are near the minimum, while the drop shunt remainslow, would indicate a developing fault of the receiver. It is recommended that thereceiver is changed to see if this will bring the track relay voltage and drop shuntback into correspondence.

Track relay voltages which are near the maximum, while the drop shunt remainshigh, would indicate the transmitter not producing the required waveform. It isrecommended that the transmitter is changed to see if this will bring the trackrelay voltage and drop shunt back into correspondence.


HVI Track Circuits

G 2 R A I L T R A C K


GK/RC0756Issue TwoDate December 1998Page G 2 of 4

2.3 Test T4: Relay End VoltageThe rail voltage is a measure of the energisation level of the track circuit. It willchange inversely proportional to the drop shunt value and will be affected by thesame factors.

Values of the relay end voltage towards the maximum should be accompaniedby higher limit values of track relay voltage (T3) and lower limit values of dropshunt (T1).

Values of the relay end voltage towards the minimum should be accompaniedby lower limit values of track relay voltage (T3) and higher limit values of dropshunt (T1).

If the rail voltage is high and the drop shunt is high, it indicates that thetransmitter is providing an unsatisfactory waveform. It is recommended that thetransmitter is changed to re–establish the inverse correspondence between therail voltage and the drop shunt value.

2.4 Test T5: Current Provided by EquipmentThe ability of the transmitter to provide power to the track circuit may be checkedby measuring the current at the relay end. As the instrument for measuring thewaveform will only measure voltages, it is necessary to pass the current througha 0.5Ω resistor to measure a representative voltage.

The value of this voltage is individual to each track circuit, being affected bylength, the length of its tail cables and the complexity of S & C work. Therefore,the measurement is important as a basis for comparison rather than as anabsolute value. The voltage measured at the maintenance visit should not differby ±3V from the commissioning result.

If the test voltage is satisfactory, but the rail and track relay voltages are low,then it is likely that the track circuit is being shunted by poor ballast or debris,and it should be examined.

If the test voltage is low, but the rail voltage is satisfactory, it is likely that thetrack circuit bonding or tail cables are becoming defective and they should beexamined.


HVI Track Circuits

R A I L T R A C K G 3


GK/RC0756Issue TwoDate December 1998Page G3 of 4

3 Track CircuitMaintenanceRecord Card

Figure G1


HVI Track Circuits

G 4 R A I L T R A C K


GK/RC0756Issue TwoDate December 1998Page G 4 of 4

Figure G2 (Reverse of Figure G1)


HVI Track Circuits

R A I L T R A C K H 1


GK/RC0756Issue TwoDate December 1998Page H1 of 7

Part HFault Finding

1 IntroductionThis Part deals with the diagnosis and repair of failures on HVI track circuits. Itshould be read in conjunction with GK/RC0752 Part J, which explains how todefine types of failure present.

Staff who are not experienced with HVI track circuits, should familiarisethemselves with the tests (Figure F1) and sequential testing before commencingactual fault finding.

2 Sequential TestingThis fault finding procedure is based on sequentially testing the equipment andwiring to isolate the location of the fault in a manner which minimises movementfrom one test location to another. There is no standard order in which to isolatethe fault, each case must be dealt with on its own merits. In each case, if onetest cannot reveal the failure then another test must be undertaken as directed.

It will be instructive to consult the “Track Circuit Maintenance Record Card” tosee which readings have dramatically changed, thus giving an indication as tothe source of the failure.

As the HVI track circuit has proved to be very reliable in service, only commonitems (eg. fuses, resistors and bonding equipment) need to be taken on site. Itis recommended that a minimum of a transmitter, track transformer and a relayare close to hand.

Using the Table of Tests (see Figure F1) and the Test Diagrams 1 to 4 (FigureH1, Figure H2, Figure H3 and Figure H4); it should be possible to locate the faultwith the aid of the following instructions.

2.1 Relay Voltage Test : Test T3This test is to check whether the track relay is faulty:

Result (a): Both voltages are within specified limits.

• Action: Replace Track Relay.

Result(b): One or both voltages are low or absent.

• Action: Proceed to (Test T3a): Receiver Output Voltage Test.

2.2 Receiver Output Voltage Test : Test 3a(See Figure H1)This test is measured at the output of the receiver on V1+ to V and V2+ to Vrespectively. The expected results are identical to Test T3 above:

Result (a): Voltage is within specified limits.

• Action: Check wiring between receiver and track relay fordisconnection or high resistance.

Result (b): Voltage low or absent.

• Action: Proceed to (Test T4) Relay End Voltage Test.


HVI Track Circuits

H 2 R A I L T R A C K


GK/RC0756Issue TwoDate December 1998Page H 2 of 7

2.3 Relay End Voltage Test : Test T4This test is to check whether the failure is at the feed end or the relay end of thetrack circuit.

Result (a): Voltage within specified limits.

• Action: Replace track transformer/resistor.If failure remains,replace receiver; if failure still remains, check wiring/cabling.

Result (b): Voltage absent.

• Action: Check bonding/cabling: Possible bonding disconnection.

Result (c): Voltage is below specified limits.

• Action: Further test required; disconnect resistor from R terminal of track transformer If voltage remains low, it is possible there is a short circuit on the track. If the voltage increases, it indicates that the fault is within the relay end equipment.

Result (d): One or both polarities remain below specified limits

• Action: Proceed to (Test T5) Load Test.

2.4 Load Test : Test T5This test is to check the voltage at the relay end while the track is under load.This will prove the electrical integrity of the track circuit bonding.

Result (a): Voltage is below specified limits or greatly below previous readings.

• Action: Proceed to (Test T6) Supply tests.

Result (b): Voltage is within specified limits.

• Action: Check insulations in the track circuit.

2.5 Supply Tests : Test T6This test is to check that the supply voltage is correct, the supply fuse is intactand the equipment is drawing the correct load current.

Result(a): Voltage is incorrect.

• Action: Inform Supervisor, as further tests unrelated to trackcircuit fault finding will be required.

Result(b): Supply current not between 0.3A and 0.5A.

• Action: Proceed to (Test T7) Transmitter Power Test.

Result(c): Current is between specified limits.

• Action: Proceed to (Test T9) Pulse Rate Test.


HVI Track Circuits




2.6 Transmitter Power Test : Test T7This test is to see whether the track circuit is being shunted. For electrified lines,disconnect resistor from terminal R of the track transformer. For non–electrifiedlines, the track connections should be removed from terminal VA of the tracktransformer.

Measure voltages as described for Test T7. Minimum voltage in all cases is120V.

Result (a): Voltages above specified minimum.

• Action: Inspect track circuit for poor insulation.

Result (b): Voltages at or below specified minimum.

• Action: Proceed to (Test T8) Feed End Voltage Test.

Note: Reconnect wire to track transformer terminal.

2.7 Feed End Voltage Test : Test T8This test is to check whether the voltage on the output side of the transformer iswithin limits.

Result (a): Voltage is below specified limits.

• Action: Replace transmitter

Note: Damage may result if the mains supply is not disconnected.If failure remains, replace power supply unit.

Result (b): Voltage is within specified limits.

• Action: Inspect track circuit bonding and rails.

Result (c): Voltage is below specified limits.

• Action: Test for track circuit being shunted by insulation failure.

Result (d): Voltage absent.

• Action: Check track transformer/resistor.

2.8 Pulse Rate Test : Test T9This test is to check whether the pulse rate is within limits.

Result (a): Number of pulses not within specified limits.

• Action: Replace transmitter and/or power supply unit.

Note: Damage may result if the mains supply is not disconnected.

Result (b): Number of pulses within specified limits.

• Action: Proceed to (Test T8) Feed End Voltage Test.


HVI Track Circuits




Figure H1 Test Diagram 1 Electrified Lines Feed End


HVI Track Circuits




Figure H2 Test Diagram 2 Electrified Lines Relay End


HVI Track Circuits




Figure H3 Test Diagram 3 Non–electrified Lines Feed End


HVI Track Circuits




Figure H4 Test Diagram 4 Non–electrified Lines Relay End




HVI Track Circuits

R A I L T R A C K R e f 1


GK/RC0756Issue TwoDate December 1998Page Ref1 of 1

References(Railway Group Standards references correct as at Catalogue 13)

Railway StandardsGK/RC0241 Signalling Maintenance SpecificationsGK/RC0752 General Information Track CircuitsGK/RC0753 Requirements for A.C. TractionGK/RH0730 Signalling Testing HandbookGK/RH0740 Signalling Maintenance Testing HandbookGK/RT0251 Track CircuitsGK/RT0252 Minimum Requirements for the Bonding of Track CircuitsGK/RT0405 HVI Track Circuits on A.C. Electrified LinesGS/ES0872 Railway Signalling Cables

BR930 D.C. Neutral Line Relays (Plug–in Type) for Railway SignallingPurposes

BR933 Miniature Tractive Armature A.C. Immune D.C. Slow Pick-upNeutral Line Plug-in Type for Railway Signalling Purposes

Railway Standard DrawingsBRS-SM 440 T2Signalling Equipment Framework Tx/PSU Mounting Plate

for GEC Alsthom HVI Track CircuitsBRS-SM 440 T3 Signalling Equipment Framework Relay/Rx Mounting Plate

for GEC Alsthom HVI Track Circuits

National / International StandardBS714 Cartridge fuse–links for use in Railway Signalling Circuits


Documents

HVI Track Circuits - RSSB Iss 2.pdfHVI Track Circuits. 2. RAILTRACK. Railway Group Approved Code of Practice GK/RC. 0756. Issue . Two. Date . December 1998. Page 2 . …