Signalling Relays122.252.230.113/content/ppt/sig/S19.pdfAdvantages of Relays Relays can switch AC and DC, transistors can only switch DC. Relays can switch high voltages, transistors

Signalling Relays

Presented by P.Shakila Ios5

8/21/2020 S19 Relays and cables 1

RELAYS & CABLES

The orthodox mechanical signalling system was replaced with Electrical signalling.

Two essential components are widely used in all the Electrical signalling systems. They are "Relays" & Cables ".


INTRODUCTION :


RELAY CABLE

What is a Relay ?

A relay is an electromagnetic device used to convey information from one circuit to another circuit through a set of contacts i.e. front or back contacts.

Switching device used for remote control and succession control of various electrical equipment.

Capable of protecting the controlled equipment from cross feeding and overloading

Cater for speedy operations.

Most of the relays in present day signaling are electromagnetic devices,

But even the electronic components like diode/transistors/ Integrated Chips etc are also used as relays


Principle-Electromagnetic relays


Advantages of Relays

Relays can switch AC and DC, transistors can only switch DC.

Relays can switch high voltages, transistors cannot.

Relays are a better choice for switching large currents (> 5A).

Relays can switch many contacts at once.


Disadvantages of Relays

Relays are bulkier than transistors for switching small currents.

Relays cannot switch rapidly whereas transistors can switch many times per second.

Relays use more power due to the current flowing through their coil.

Relays require more current than many chips can provide, so a low power transistor may be needed to switch the current for the relay's coil.


Classification of Relays:

1 Based on their application,

Line relays

Track Relays

Lamp Proving Relays

Timer Relays

Flasher Relays

Contactor Relays

Biased Relays



LINE RELAY TRACK RELAY


LAMP CHECKING RELAY

TIMER RELAY


CONTACTOR RELAY BIASED RELAY

Classification of Relays:

2 Based on type of contact material used

Metal to Metal contact Relays

Metal to Carbon contact Relays

3 Based on polarity requirement

Polar Relay

Neutral Relay


Classification of Signaling Relays

4. According to their importance in ensuring train safety

a) Vital relays : relays directly used for

traffic control like signal, point, track

detection etc.

b) Non-vital relays : relays used for controlling aids like warning buzzers, indications etc.



5. According to special provisions to ensure reliability of their contacts

a) Proved type : Relays for which proving of normalization is necessary after every

operation (metal-to-metal contact relay).

b) Non-proved type : Relays for which above requirement is not necessary as their contacts have at least one non-fusible contact (Metal to carbon contact relays).



6. Based on the source of feed

a) DC relays

i) DC neutral relays : are not affected by the polarity of DC supply and close same set of contacts on energization.

ii) Polar relays : are sensitive to polarity of DC supply and

close different sets of contacts depending upon the polarity of the DC supply.



b) AC relays : AC induction motor track relays are used at some places in DC electrified area.

c) Electronic relays- DC relays with electronic components in them.

7. Relays can also be classified basing on their level of immunity to external AC voltages :

a) AC immunized- Relays

b) Non immunized Relays


SYMBOLS AND NOMENCLATURE OF RELAYS AND WIRING PRACTICE:

The power signalling systems on our railways follow two practices:

(1) The British Railway practice and

(2) The Continental or German practice.

These two systems have an individual language of symbols and nomenclature .However they have a few common elements also


MEANING OF LETTERS USED IN SYMBOLS

AND NOMENCLATURE

Letter Description

A Approach, automatic

B Block, Bolt

C Checking or proving

D Clear (green)Decoding

E Light: heat (externally applied)

F Fog

G Ground, gate, signal aspect H Caution (yellow)

I Indicator J Time (delayed action)

K Indicating or detecting

L Locking, left,

M Magnet 8/21/2020 S19 Relays and cables 18

MEANING OF LETTERS USED IN SYMBOLS

AND NOMENCLATURE

Letter Description

N Normal (push button or key)

O Retarder

P Repeater

Q Treadle or bar

R Reverse, right, red

S Stick

T Track circuit

U Route

V Train stop

W Point

X Audible indicator

Y Slotting

Z Zone, Any special term defined 8/21/2020 S19 Relays and cables 19

N Switch / Knob Contact in Normal Position

Switch / Knob Contact in Reverse PositionR

Relay Coil (Name of Relay is written inside the rectangle)R1 R2

DescriptionSymbol

Closed Contact when Relay is in Energised condition

Slow to release Relay

Slow to pickup Relay

Double Coil Relay

R1 R3

A C Immunised Relay

Time Element Relay front Contact (Energised Condition)

Flasher Relay contacts

NORMAL / REVERSE Contacts

(Front Contact)

(Back Contact)Closed Contact when Relay is in de-energised condition

R2 R4

Time Element Relay front Contact (de-Energised Condition)

R

N(3-Position Polar Relay) (Dependant type)

N NORMAL Contacts (Energisation on NORMAL side)

(3-Position Polar Relay) (independant type)

R REVERSE Contacts (Energisation on REVERSE side)


D De-Energised Contacts


NORMAL Contacts

R (2-Position Polar Relay) (independant type)

REVERSE Contacts

R

N

N



(2-Position Polar Relay) (Dependant type)

S.No.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Symbols for british practise


N Switch / Knob Contact in Normal Position

Switch / Knob Contact in Reverse PositionR

Relay Coil (Name of Relay is written inside the rectangle)R1 R2

DescriptionSymbol

Closed Contact when Relay is in Energised condition

Slow to release Relay

Slow to pickup Relay

Double Coil Relay

R1 R3

A C Immunised Relay

Time Element Relay front Contact (Energised Condition)

Flasher Relay contacts


(Front Contact)

(Back Contact)Closed Contact when Relay is in de-energised condition

R2 R4

Time Element Relay front Contact (de-Energised Condition)

R

N(3-Position Polar Relay) (Dependant type)

N NORMAL Contacts (Energisation on NORMAL side)


R REVERSE Contacts (Energisation on REVERSE side)


D De-Energised Contacts


NORMAL Contacts

R (2-Position Polar Relay) (independant type)

REVERSE Contacts

R

N

N



(2-Position Polar Relay) (Dependant type)

S.No.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Symbols for british practise


British relays and Nomenclatures

Sr No Name Description

1 TSR Track stick relay

2 UCR Route checking relay

3 ASR Approach stick relay

4 WLR Point lock relay

5 WNR Point normal (operation ) control relay

6 WRR Point reverse (operation ) control relay

7 NWKR Normal point ( position ) indication relay

8 RWKR Reverse point ( position ) indication relay

9 TRSR Track right stick relay

10 TLSR Track left stick relay

11 SMCR Station master’s control relay

12 UYR1,UYR2 Sequential route release relays


CIRCUIT IN BRITISH PRACTICE


(Top Relay) Interlocked Relay Reverse Coil

Neutral Relay

Symbol Description

Interlocked Relay Normal Coil (Bottom Relay)

Track Relay

Track Repeater Relay

Block Relay in Automatic Territory

Time Element Relay T

Indicates that a Neutral relay is normally energized

Indicates that a Neutral relay is normally de energized

Indicates that an Interlocked relay is normally latched

(Normal coil)

(Reverse Coil) Indicates that an Interlocked Relay is normally de

latched

Make Contact

Break Contact

Make contact of a Neutral Relay that is normally picked up (Front Contact)

Break contact of a Neutral Relay that is normally picked up (Back Contact)

Make contact of a Neutral Relay that is normally drop (Back Contact)

Break contact of a Neutral Relay that is normally drop, (Front Contact)

Make contact of a Interlocked Relay that is normally latched, (Front Contact)

Break contact of a Interlocked Relay that is normally delatched (Back Contact)

Make contactof a Interlocked Relay that is normally delatched (Back Contact)

Break contact of a Interlocked Relay that is normally delatchedt (Front Contact)

S.No.

19

18

17

16

15

14

12

13

11

10

9

8

7

5

6

4

3

2

1

21

20

Symbols used in Siemens Practice


Siemens Interlocked Relay Symbols


Nomenclature of Siemens Relays

RELAY NOMENLATURES

GNR Signal button relay

GNCR Signal button checking relay

SH-GNR Shunt signal button relay.

CO-GGNR Common button relay for calling-on

signals

EGGNR/ERNR Common button relay to replace any

signal at 'ON"

UNR Route Button relay.



RELAY NOMENLATURES

UNR Route Button relay.

UNCR Route button checking relay

EUYNR Emergency sub-route release button

relay.

EUYZ Emergency sub-route release

operation counter.

EUUYNR Emergency ( full ) route release

button relay.

EUUYZ Emergency (full ) route release

operation counter

EUUYNCR Emergency (full ) route release button



RELAY NOMENLATURES

EUYR Emergency route release relay

( common for sub route and full route cancellation)

WNR Point button relay.

WNCR Point button checking relay

WWNR Common point button relay.

(when point zone track circuits are up)

EWNR Emergency Common point button relay

(when point zone track circuit is down)

EWZ Emergency points operation counter 8/21/2020 S19 Relays and cables 28


WLR Point locking relay

WJR Point time delay relay

WR Point contractor relay (heavy duty contractor relay)

CHYNR Crank handle slot release button relay.

CHYRNR Crank handle slot return button relay

CHKLR Crank handle key lock relay.


Siemens Circuits

CCT-1(SHT- 5)

S12 GN

S12 GNR

S12 EGNR

CCT-5(SHT-7)

5B Z1UR1

LL1 UNPR

S3 GNPR S12 GNPR

2 /3T UNPR LL2 UNPR


Terms connected with Relays

1. Non-fusible contacts: A pair of contacts in which one contact element comprises of non-fusible material, which presents practically no risk of welding of contacts.

2. Carbon contacts: 'carbon' in the expression 'carbon - to- metal contacts' is used as a general term covering graphite and compounds and mixture of carbon and metals.

3. Metal contacts: 'Metal' in the expression 'metal to metal contacts' is used as a general term covering the use of silver, silver cadmium oxide, tungsten, platinum or any other suitable material to an approved specification.



4. Front contact: That contact which is made with 'arm contact' when the relay is energized.

5. Back contact: That contact which is made with 'arm contact' when the relay is de-energized.

6. Arm contact: That contact which is movable part of the pair of contacts and is made with front contacts when the relay is energized and with back contact when the relay is de-energized.

7. Arm: The movable part of the pair of contacts.



• Dependent contact – a movable arm contact connects to a FC when relay is energized and the same arm contact connects to a back contact when the relay is de-energized (4F/B)

• Independent contact – the condition in which the movable arm contact connects to either a front or a back contact and not to the both (2F,2F/2B)

• Pick up value – the value of current just enough to close all front contacts under specified conditions


Front contact

Arm contact

Back contact

DEPENDENT CONTACTS


Front contact

Back contact

INDEPENDENT CONTACTS



10. Contact element: Contact piece, which is secured to a contact spring.

11. Wiping (self-cleaning) contacts: Contacts designed to have certain relative motion, during the interval from the instant of touching until completion of the crossing motion.

12. Contact follow: That distance which the movable arm contact travels after touching the front or back contact.

13. Contact bounce: means the uncontrolled making and breaking of the contact after it has closed first.



Drop away/Release value - the value of current at which all front contacts just open

Operate – all front contacts just made

Full operate – the condition when armature has completed its maximum travel

Release – all front contacts just broken

Full Release – when armature returns back fully to stop postion

Percentage release = drop away/pick up x 100


Operate Time (of )

(a) Back Contact: Means the time interval from the instant of application of the current to the coil until breaking of the back contact, which is the last to break.

(b) Front contact: Means time interval from the instant of application of the current to the coil until closing of the front contact which is the last to close and the contact bounce has ceased.

Release Time (of).

(a) Front Contact: Means the time interval from the instant of removal of energy to the coil until breaking of the front contact, which is the last to break.

(b) Back contact: Means the time interval from the instant of removal of the energy to the coil until closing of the back contact which is the last to close and the contact bounce has ceased.



CHARACTERISTICS OF ELECTRO-

MAGNETIC RELAY:

The following are the important characteristics of electro-magnetic relays. Basing on these characteristics components and designs features of relays are decided .

Force of attraction

Effect of air gap.

Effect of Hysteresis

Transient condition.


Force of attraction:

In any electro-magnetic system, the force of attraction is given by.

F B2 a

Where: B - is the flux density and a - is the cross sectional area of the particular part of the magnetic circuit.

Effect of air gap:

If the air gap is not available, then the residual magnetism fluxes might cause the armature to be retained when the supply is disconnected. For this reason, residual pins are provided to ensure a definite minimum air gap in the energised position.

CHARACTERISTICS OF

ELECTRO-MAGNETIC RELAY:


Effect of Hysteresis:

Hysteresis is the property by which the flux produced lags behind the current. To overcome the effect of Hysteresis the relay core is made of material having high permeability and low retentivity

This reduces the difference between pick up value and Drop away value. By selecting good quality core material, Percentage release and sensitivity of the relay will be improve.

Transient Condition:

When the voltage is applied or disconnected from the coils, it takes some little time before the current become steady. These are known as transient conditions” and are important so far as track relays are concerned as they effect the release time of the track relay

CHARACTERISTICS OF



To reduce releasing time to a minimum value

The relay iron should have low Hysteresis loss and low retentivity.

The degree of over energization of the relay should be restricted

Connecting a suitable external resistance in series with the relay to keep L/R ratio low.

CHARACTERISTICS OF



Use relay with minimum contacts, as they require lesser current which keeps inductance value low

Train working safety is ensured only if the track relay of shortest length track circuit is released before a light engine running at a highest permitted speed clears it. Otherwise, the track circuit occupation may go undetected. To avoid this, a special provision has to be made in signal control circuits, wherever necessary.

CHARACTERISTICS OF



ELECTROMAGNETIC RELAY


Q-SERIES RELAYS

Presented By P.Shakila IOS5

6/4/2020 S19 Relaya and cables 45

Plug-in type DC Neutral Line Relays ( Non –Proved type )

The Plug-in type DC Neutral Line Relays which suit to the BR specifications and used over Indian Railways are known as Q-series relays.

No separate IRS specification issued for these relays .But they confirm to IRS spec no. S23 and S34 ( for testing procedures).

They are known as non –proved type because unlike proved type relays their last deenergised state need not be proved when ever they are reenergized ,


Base

Heel

piece

Electromagnet Non-magnetic

residual pin

Armature

Handle

Pusher

spring

Transparent

cover

Adjustment

card Operating

arm


Constructional Features of the q-series Dc neutral relay

Standard common plug board with coding pin arrangement is used to prevent a wrong relay being plugged.

Each relay is provided with 5 coding pins and accordingly 5 holes (out of 10 i.e. A,B,C,D,E,F,G,H,J,K) are drilled in the plug board. These are known as code numbers. No electrical connection establishes between relay and plug board until code pins engage correctly. Six more code pin positions exist (L,M,N,X,Y,Z) which are used for special relays.



Connectors, which are positively locked in to the plug board and can be with drawn by a special tool to permit easy disconnection.

Means for terminating permanent wiring to plug board on the connectors both by crimping & soldering.

Registration device with specified coding

combination in order to prevent a wrong relay being

plugged.



No electrical connection possible between plug board and the relay base until code pins have correctly engaged

Fixed contact positioned by adjustment cards and moving contact positioned by operating arm drive by the armature.

Provision of helical spring to provide definite back contact pressure and aid in return torque.

Provided with Non-proved (metal to carbon contacts) and all are independent contacts only.



Constructional Features (coding pins)

QN1 12F/4B

ABCDE

QN1 8F/8B

ABCDF

QNA1 12F/4B

ABDFH

QNA1 8F/8B

ABDGH

QLI

ABDEG

QBA1 12F/4B

ABFGH


Constructional Features (coding pins)

QBA1 8F/8B ACDEH

QS3 (12V, 1000 ohms)

CDEKX

QT2 DEFJX

QTA2

FGHKX


Constructional Features

Conform to IRS: S 23 & S 34, besides relevant BRS specification

Plug-socket type of inter-connection between relay and plug board

Retaining clip to hold relay firmly to ensure firm electrical connections.

All contacts are independent and non-proved type

Permanent wiring on plug board is terminated after proper crimping and soldering of wires on the connectors



Connectors are positively locked in plug board and at the same time they can easily be withdrawn with the help of a special tool in case of need

Fixed contacts are positioned by adjustment cards and moving contacts are positioned by the operating arm driven by the armature.



A non-magnetic residual/stop pin on the face of armature helps to reduce the effect of hysteresis/residual magnetism

A helical pusher spring helps to restore relay to full released condition and helps back contacts make properly when relay is de-energized

All moving arm contacts are silver contacts and all fixed front and back contacts are of silver impregnated graphite (non-fusing).


NML

ZYX

FIG : 4.3

KJ

HGFE

DCBA

ABCD

1

2

3

4

5

6

7

8

R1

R3R4

R2

8

7

6

5

4

3

2

1

Interchangeable contacts

B5B6, B7B8

C5C6, C7C8

Front contacts

A1A2, A3A4

B1B2, B3B4

C1C2, C3C4

D1D2, D3D4

Back contacts

A5A6, A7A8

D5D6, D7D8 6/4/2020 S19 Relaya and cables 57

Standard Contact Arrangements

Q-series relays are provided with a maximum of 16 numbers of independent contacts. The standard contact configurations for various types of relays are: Line Relays – 12F/4B, 8F/8B, 8F/4B, 6F/6B 6F/2B, 4F/4B Track Relays – 2F/1B, 2F/2B ECRs (Lamp Checking Relays) – 3F/3B, 4F/4B * All the front and back contacts are “independent”. FC - “metal-to-carbon”, BC - “metal-to-carbon”.


Contact Configurations


TYPES OF Q-SERIES RELAYS

QN1 QNN1 QNA1 QNA1K QS3 QSA3 QB1 QBCA1 QSPA1 QSRA1 QL1 QJ1


QN1 Relay

This is the fundamental Q series relay. All other relays of the Q series have been developed around the QN1 in order to standardize the components.

Iron circuits and contact stacks are mounted on a molded base of extremely stable non-hygroscopic thermosetting plastic (A thermo set material cannot be melted and re-molded).

Rated life of a relay is 1000000 cycles


QN1 Relay

Contact springs are made of wear,corrosion & fatigue resistant phosphor bronze which extend beyond the base.

Armature pivots on a phosphor bronze plate riveted to the heel piece.

The magnetic circuit consisting of L shaped heel piece, electromagnet (core & coil) and armature are fixed to the thermosetting base below the contact stacks


QN1 Relay


Applications and Contact Configuration QN1 Relays

Contact Configuration – 12F/4B, 8F/8B, 8F/4B, 6F/6B, 4F/4B Applications – All circuits in non-electrified sections and internal circuits in electrified sections


QN1 – Technical Data

Rated voltage : 24

Pick up voltage : 19.2 Volts

Coil resistance : 400 Ω

Drop away voltage : 3.6 V

Pick up time : 150 millisecond

Drop away time : 20 millisecond

Operating current : 60 mA

Spec : BRS 930A, IRS: S 23 & S 34



QN1K Relay

QNN1 – DC Twin Neutral Line Relay

Conforms to BRS 960

It is a combination of two neutral relays with a common heel piece and a common base.

The two relays are independent and can be used for two different unrelated purposes.

Affects saving of space when requirement of number of contacts is less.

Equal number of contacts either 4F/4B or 6F/2B on both the relays


QNN1


Rated/normal working voltage : 24



Application : all circuits in non electrified sections and internal circuits in AC electrified sections especially when number of contacts required is less and/or space constraint is there.

QNN1 – DC Twin Neutral Line Relay


The relay is same as QN1 relay except that a copper slug is provided in this relay at the armature end of the core to achieve immunity against AC voltages.

When AC current passes through relay coil, the flux set up through air gap and armature is also linked with copper slugs. This induces eddy currents in copper slug the flux generated by which opposes the flux which caused the eddy currents in slug.

QNA1-AC Immunized DC Neutral Line Relay


QNA1 – Technical Data




Pick up time : 220 millisecond

Drop away time : 70 millisecond

Operating current : 115-120 mA

AC Immunity level : 120 V AC 1- Phase 50 Hz


QNA1 RELAY


Applications and Contact Configurationof QNA1 Relays

Contact Configuration – 12F/4B, 8F/8B, 6F/6B, 4F/4B

Applications – All external circuits in electrified sections


Provisions of Spec – IRS: S60-78 for AC Immunity Requirements

The relay shall not make by sudden application of 1000V 50 Hz AC

Relay not to break its back contact when1000Vrms is applied gradually or abruptly.

Maximum P.U transfer and release transfer time not more than 200 m Seconds when relays energized with 80% rated voltage.


QN1 QNA1

Pick up voltage – 19.2 V

Pick up voltage – 19.2 V

Drop away voltage – 3.6 V

Drop away voltage – 3.6 V

Coil resistance – 400 Ω

Coil resistance – 208Ω

Operating current – 60 mA

Operating current – 115 mA

Pick up time – 150 msec

Pick up time – 220msec

Drop away time – 20 msec

Drop away time – 70 msec

Suitable for internal ciruits of RE area

Suitable for external circuits of RE area


DC Neutral Sensitive Line Relay QS3

It is a sensitive relay designed to work on low voltage and

current.

Conforms to BRS 930

It was introduced with a drive to replace shelf type relays

Contacts are silver impregnated graphite to silver

Technical Data of QS3 Relays

Working voltage : 12V

Coil resistance : 1000 Ohms

Contact configuration : 4F/4B

Operating current : 12mA

Pick up voltage : 7.5-9.35 V

Min drop away voltage : 3.75 V


QS3 Relay

Applications of QS3 Relays

Its application in most of the zonal railways started with the drive to do away with shelf type relays from axle counter circuits for safety reasons.

Accordingly 12 Volt version is being used as evaluator relay (EVR) and supervisory relay (SUPR) in analog axle counters to suit output of axle counter cards.

24V as well as 12V versions are being used for inner distant, distant and IB circuit applications in non-electrified sections where voltage drop becomes critical.

DC Neutral Sensitive AC Immunized Line Relay QSA3

Conforms to BRS 931A

Contacts are silver impregnated graphite to silver

It is primarily for use over long supply lines

A copper slug at the armature end of the core provides AC immunity.

Technical Data & Applications of QSA3 Relays

Working voltage : 12V / 24V

Coil resistance : 1000 Ohms

Contact configuration : 4F/4B

Operating current : 12mA / 24mA

Application : 24V as well as 12V versions are being used for inner distant, distant and IB circuit applications in electrified sections where voltage drop becomes critical.

DC Biased Neutral Line Relay QB3

This relay is sensitive to the polarity of the DC supply and operates only when rated DC supply of correct polarity is applied across its coil.

The armature does not get attracted even when a supply 20 times its rated voltage is applied in reverse polarity.

This biasing feature is attained through a permanent magnet fixed on the core.





Neither electromagnetic coil flux nor permanent magnet can hold the armature in attracted position on their own.

The armature gets attracted and remains attracted only when both the fluxes act together to get added up.

Technical Data & Applications – QB3 Relays

Rated voltage and current – 12V DC, 60mA

Coil resistance – 200 ohms

Contact configuration – 4F/2B

Pick up current – 45 mA

Pick up/drop away time – 380/20 millisec.

Applications of QB3

Being biased, two relays can be worked on a single pair of conductors - thus saving a pair of conductors.

These are used in Podanur make single line block instruments as code receiving and checking relays.

The instrument contains 36 relays, 3 of which are QB3 type. These are named CRR(N), CRR(R) and TCKR (Transmission Code Checking Relays).

These instruments are able to work on a single pair of conductors because of these relays.

QBA1- Q series Biased & AC Immunized Relay

To make the relay AC immunized, copper slug is provided at its armature end adjacent to the permanent magnet.

Coil resistance – 200 ohms Working voltage – 24V DC AC Immunity – 1000V AC Pick up/drop away voltage – 19.2/3.6 V

Application – this also affects saving of one pair of conductors and is used in Daido single line block instruments (NR, BLR).



QBA1 Relay


QBA1 Relay


QBCA1 Relay

Biased AC immunized relay with heavy duty front contacts

It has 2 heavy duty front contacts and 4 normal rating current rating back contacts.

Heavy duty front contacts are rated for 30 Amps.

Magnet pieces are held close to the heavy duty contacts and they blow or disperse the electric arc before it has a chance to grow and burn.


QBCA1 Relays

Immune to 1000V AC The armature does not get attracted even when a supply 20 times its rated voltage is applied in reverse polarity. Conforms to BRS 943 & 966 Two extension springs behind the base are joined with front contacts and their springs so that 2 wires can be connected for sharing heavy load currents through these contacts.


Contacts are silver impregnated graphite to silver Minimum front contact pressure is 56 gms as against 28 gms for other similar metal-to-carbon relays.

Two natural magnet pieces called magnetic called Blow out magnets are fixed on a bracket by the side of front contact elements .Spark quenching by these magnets during operation makes it possible for them to carry heavy currents

QBCA1 Relays


Technical Data & Applications – QBCA1 Relays

Rated voltage and current – 24V DC, 120mA Coil resistance – 208 ohms Contact configuration – 2F(heavy duty)/4B Pick up/drop away voltage – 19.2/3.6 V

Application – The relay is designed primarily for control of point machines in AC electrified sections.


Technical Data & Applications – QBCA1 Relays

Rated voltage and current – 24V DC, 120mA Coil resistance – 208 ohms

Contact configuration – 2F(heavy duty)/4B

Pick up/drop away voltage – 19.2/3.6 V

Application – The relay is designed primarily for control of point machines in AC electrified sections.

1) Permanent Magnet

2) Copper slug

3) Blow out magnets

QBCA1 Relay features :

QBCA1 Relay HD Contacts


QBCA1 Relay HD Contacts


QSPA1-Slow to Pick up Relay

Conforms to BRS 933A Magnetic shunt at the armature end makes the relay slow to pick up. The flux passes through the shunt initially and the relay picks up once the magnetic shunt saturates. Copper slug at heel piece end provides AC immunity.


QSPA1 RELAY


Slow to Pick up Relays


Application, Technical Data-QSPA1

Used as TPRs in RE areas to avoid unsafe situations in cases of OHE snappings.

Pick up time – 540-600 millisecond Release time – 140-200 millisecond Working voltage -24v DC Coil resistance – 208 ohms Contact configuration – 8F/4B AC immunity level – 1000 v AC


QSRA1-Slow to Release Relay

Conforms to BRS 934A Magnetic shunt at the heel piece end makes the relay slow to release. Saturated magnetic shunt helps to maintain the flux for a while as supply to the coil is cut off. Copper slug at heel piece end provides AC immunity.

QSRA1 RELAY


Slow to Release Relays


Application, Technical Data QSRA!

Used as HPRs, DPRs in RE areas to make them insensitive to momentary supply fluctuations and momentary track relay dropping, ECRs, button failure/point failure/signal failure indication relays etc DA time – 260 millisecond Working voltage -24v DC Coil resistance – 208 ohms Contact configuration – 8F/4B AC immunity level – 1000 v AC


QL1-Magnetic Latch Relay

A permanent magnet at the heel piece end keeps it latched in the operated position.

No residual pin – requires power supply for releasing the relay

Reverse/operating coil – 150 ohms (to operate) and normal/release coil – 680 ohms (to release).

The two coils are wound on the same core but in the opposite directions. Feed to the operating coil is cut by the back contact of repeater relay.

Feed to normal coil is cut off internally with the help of a front contact as prolonged feed may demagnetize the permanent magnet.

QL1


QL1-Magnetic Latch Relay


Applications of QL1 Relay

TCFR, TGTR, TAR and TOLAR relays in Podanur make push button block instruments

Working voltage --- 24 v DC

In point circuits to prove correspondence Available in 11F/4B and 8F/6B configurations

QJ1 Relay Constructional Details

It contains a heating element (TH) and a DC neutral relay

( JSR) which combine together and operate an external relay after a preset time.

Heating coil is wound over a bimetallic strip of invar (an

alloy containing 64% iron and 36% nickel) at top and brass at bottom.

Invar has the lowest thermal expansion of any known metal or alloy from room temperature up to 230°C

QJ1 Relay Operating Principle

When heated, brass expands more as compared to invar and the bimetallic strip bends upward as one end of the strip is fixed.

This movement causes a set of contact to make (hot contact) after a predetermined time.

Closing of hot contact causes internal neutral relay (JSR) to pick up, which in turn cuts off the feed to the heating coil.

QJ1 Relay Operating Principle

.There by supply to TH coil is stopped. After some time, the heating element cools off and its arm closes with the cold contact. This cold contact in series with a 'JSR' front contact extends feed to an external relay (JR).

The complete cycle of making a hot contact and then a cold contact ensures that the thermal contacts are normalized before each operation. This in turn results in the time delay being equal for all operations.

In this relay, the time lapse during the 'cool off’ of the heating element is thrice the time lapse during its heating.


QJ1-Relay


QJ1-Relay

TPRA1

1

BD TH*

* NOT REQUIRED WHERE THERE

IS NO APPROACH TRACK

TH(HOT)

JSR

JSR

TH(COLD) JSR

JR

NEUTRAL RELAY

JSR

QJ1-Relay


Electronic Timer Relay

Siemens Relays

Presented By P.Shakila IOS5



K50 Relays DC Neutral Line Relays

Metal-to-Metal Contacts Proved Type


K-50 Proved Type Relays

These are metal to metal contact miniature plug in type relays . Manufactured by M/s Siemens As metal contacts are used they may get welded during operation due to sparking Hence to avoid any unsafe operation , these relays are made proved type. Proved Type – Before using its operated contact to control a function it is ensured that the relay was in released condition earlier. IRS Spec. S46/74




Relay construction

As seen in the diagram, the contact springs are stacked below the yoke which extends beneath the core. The armature when de-energized rests against stop stirrup. A contact bar with pins on it is rigidly screwed to an extension of the armature. A pusher spring provided between the armature extension and the stop stirrup is compressed when the armature is attracted and helps during its release when the relay is de-energized.


1 CONTACT BAR 7 HEEL PIECE

2 PRESSING AWAY SPRING 8.PLACE FOR RELAY TYPE MARKING

3STOP STIRRUP 9.SPRING SUPPORT

4 ARMATURE 10.CONTACT SPRING

5 RESIDUAL PIN 11.CONTACT RIVET

6 MAGNETIC CORE 12.CONTACT PIN



Contact

bar

Pusher

spring

Magnetic

core Armature

Contact spring Spring

support

Contac

t pin

Contact

rivet


General Characteristics of K-50 Relays

Plug-in, Proved type DC Miniature Relays

Independent Type of contacts (Max 8 Nos )

PU Time : 25- 60 m sec; Drop away time : 7 – 15 m sec.

(For AC immunized relays : 200 m sec / 50 m sec)

60V Operation (Range : 50-110V)

Contact resistance – 0.05 Ohm

Guide pins to prevent inverse plugging

Code pins to prevent plugging of wrong type

Contact current rating : 3 A Continuous, 5 A for 30 sec (SW)


General Characteristics of K-50 Relays

Relays are available in form of groups (Mini, Minor, Major ). Metal to metal contact resistance is very less hence more number of contacts can be used in one circuit. To reduce arcing –1)Series double break double make contacts are used, and 2) the elliptical shape of the contact element and cylindrical shape of contact pins provides less contact area.3)Wiping action of contacts also called as self cleaning. Standard contact arrangement – Front 2 3 4 6 5 4 Back 2 3 2 2 3 4


Relays are classified as: A type, B type and E type on the basis of

thickness of residual pin/separating pin. (a) K50-A type: (0.35 mm residual pin

thickness). Non ACI Neutral, Interlocking Relays. (b) K50-B type: (0.15mm residual pin

thickness). ACI Neutral and UECR (c) K50-E type: (0.45mm thickness). ON ECR and OFF ECR

Classification:


Construction, General Requirements

If a back contact remains closed accidentally, none of the front contacts shall close even at a supply voltage of 1.5 times the rated voltage.

If a front contact remains closed accidentally, all other front contacts must open and none of the back contacts should close.


K50 Neutral Relay Mini-groups

Two K50A relays with eight contacts each are fixed one below the other on a frame fitted into a back plate.

Contact springs and coil ends of relays are connected separately by wiring to two spring blocks with springs extending behind.

These springs get joined with corresponding smug fitting spring terminals on two amphenol blocks fixed on a base plate when plugged.


K50 Neutral Relay Mini-groups

External wiring is soldered on the terminals behind the base plate.

Two thick pins each on the blocks of group back plate enter into corresponding holes on base blocks and ensure correct alignment.

They also prevent relay group being plugged upside down.


Mini group Relay- View showing coils & contacts

CLASSIFICATION OF MINI GROUPS

MINI GROUP

NEUTRAL AC IMMUNISED INTERLOCKED ECR”S

6F/2B

5F/3B

4F/4B

BOTH

IMMUNISED

ONLY TOP

IMMUNISED

6F/2B

5F/3B

4F/4B

ONECR

OFF ECR

UECR


Group Coding in Mini groups :

Two code pins are provided, one at the top and one at the bottom screwed onto the base plate .

These code pins have 8 different positions( Four at the top and four at the bottom ) .They enter into corresponding holes in the back plate of the relay group when a proper group is plugged in to the base.

These code pins ensure that only a group with a similar contact configuration can be plugged in a base.

Three different codes can be found for the three contact arrangements of these groups.


Code pins positions for different relay groups :

(a) Neutral:

5F/3B (1260 ohms) 1 & 6

4F/4B (1260 ohms) 1 & 7

6F/2B (1840 ohms) 1 & 5

(b) Inter Locked:

4F/4B (615 ohms) 3 & 7

5F/3B (615 ohms) 3 & 6

6F/2B (615 ohms) 3 & 5

Relay base for

Mini group

Guide pin

Guide pin

Code pin hole

Code pin hole


Coil resistance:

Neutral relays: 5F/3B and 4F/4B: 1260 ohms, 6F/2B: 1840 ohms, Interlocked relays: All contact configurations: 615 Ohms. (More current is required for the operation of interlocked relay to overcome friction of latch pieces). Lamp checking relays: 64.1 ohms. (UECR, ON / OFF ECR).


AC immunized Relays:

Uses copper slug for AC immunization A Brass strip is provided on contact bar to reduce the release time. This acts as counter weight on the armature. Immunized to 450 V AC Coil resistance 1840 ohms. (All contact combinations) PU time: 200 msec. DA time: 50 msec.



INTERLOCKED RELAYS

Two neutral K-50 relays are latched mechanically to form an interlocked relay. Top coil is called Reverse coil and bottom coil is called as Normal coil.

Latch pieces are provided on the contact bar of a top relay and on the armature extension of a bottom relay.

A guide bracket is provided to keep the relay in alignment. Front contact of the R coil is proved in the pick up circuit of the N coil externally so that the supply is automatically cut off.

This helps to save power. Hence this is called as Economizer contact.


UTLISATION OF INTERLOCKED RELAY

a) Work As A Memory Device To Detect The Last Operation,because It Remains Picked Up In The Last Operated Position.

b) It Is Also Used To Achieve Direct Interlocking Between Two Conflicting Function Such As …..

1.SHUNT AND MAIN SIGNAL PROVIDED ON THE SAME POST Ie SH-G(R/N)R

2.Direction Determining Relay Used To Lock Two

Conflicting Signals. Zu(r/N)r


INTERLOCKED RELAY:


Contacts

Max no. of contacts is 8 in Neutral and Interlocked relays a In ECR there are 6 contacts only. Total terminations: 8 X 2 Contact + 2 X 2 Coil terminations=20 for one k50 relay. For a mini group 40 terminations are required For 4 mini group relays will mean 160 terminations, hence a 160 way tag block is used for terminations and. For 5 numbers of mini groups can be accommodated in one 200 way tag block.


Standard Contact configuration:

Neutral and Inter Locked 6F/2B, 5F/3B, 4F/4B ECRs (ON/OFF) 3F/3B. UECR 5F/1B. Contact current rating is : 5 A continuous and 3A switching.


Neutral and Interlocked relay

4F/4B configuration


4F/4B configuration



5F/3B configuration


5F/3B configuration



6F/2B configuration


6F/2B configuration

TERMINATION DETAILS

Contact nos. Rear view - Termination details

Left column

(Bottom relay)

Right column

(Top relay)

11 94 (c) 93 92 (c) 91

12 84 - - 83 82 - - 81

13 74 - - 73 72 - - 71

14 64 - - 63 62 - - 61

15 54 - - 53 52 - - 51

05 44 - - 43 42 - - 41

04 34 - - 33 32 - - 31

03 24 - - 23 22 - - 21

02 14 - - 13 12 - - 11

01 04 -Sp- 03 02 -Sp- 01


TYPES OF MINI GROUP (LINE) RELAYS & CONTACT CONFIGURATION

Control Relays Lamp Proving Relays

Neutral Interlocked ECRs

Non

ACI

ACI Both

Non-

ACI

One

ACI,

One

Non-

ACI

Both

ACI

On Off Route

6F/2B

5F/3B

4F/4B

5F/3B 6F/2B

5F/3B

4F/4B

5F/3B 5F/3B 3F/3B 3F/3B 5F/1B

ECRs


ON ASPECT ECR


OFF ASPECT ECRS


UECR



Item K-50 Q-Style

Contacts Metal to metal Metal to Carbon

Operation 60V 24V

Current 33 mA – 50 mA 60 mA

Configuration 6F/2B,5F/3B,4F/4B 12F/4B,8F/8B

Coil-R 1840/1260 Ohm 400 Ohm

PU Time 25-60 m sec 150 m sec

DA Time 7-15 m sec 20 m sec

Contact R 0.05 Ohm 0.2 Ohm

Contact rating 5A/3A 2A/3A

COMPARISON OF K-50 & Q-STYLE RELAYS

Tag block

100 way(96)- panel wiring

160 way -4 nos of mini group

200 way –one major group, 2 minor group,5 nos of mini group

Lamp checking relays

Presented

by

P.Shakila IOS5


Lamp Checking Relays

Lamp proving Relays are current sensing D.C. line relays

They operate by power drawn from the A.C. signal lamp

circuits

A current transformer is usually connected in series with the

signal lamp circuit.

The output of this current transformer is fed to a bridge

rectifier, which in turn feeds the lamp checking relay.



Purpose of ECRs

To provide a cascading arrangement.

To provide a Red lamp protection arrangement

Controlling the signal in accordance with the aspect

displayed on signal in advance.

(To provide a signal aspects indication at the

operating place.


Methods adopted for repeating the

signal aspects

Using a series resistance usually known

as potential drop method

Using a current transformer method.


RGKE

D1-D4

1000

HECR

RG

HG

NX110

110/12 V

BX110 HR 110/12 V

HR

A)Potential drop method 1

When the signal lamp is lit a potential about 10 V is obtained

and this is used for light up the indication lamp connected

across the resistor. The draw back of this method is greater

drop in voltage for indication purpos


RGKE

D1-D4

1000

HECR

RG

HG

NX110

110/12 V

BX110 HR 110/12 V

HR

A)Potential drop method 2

In the second method the voltage drop across the

variable resistor is rectified and the out put voltage

is utilised to operate a ECR relay. When the lamp

fuses, the current through the resistance decreases

and therefore the ECR relay drops.


(B) Current transformer method

In this method a current transformer is connected in series

with either the primary or the secondary of the signal

transformer. The output of this current transformer is rectified

and connected to ECR relay . Again in this three different

methods are followed basing on the type of transformers

used

i) 'I' type current transformer.

ii) ‘L' type current transformer.

iii) 'H' type current transformer.


Comparision of ECR relays

'I' type ‘L' type 'H' type

Usage For giving direct

indications at

cabins

To energise lamp

checking relay in

the ECR unit at

cabin or relay room

To energise lamp

checking relay in the

ECR unit at signal

and also for checking

main filament in

Triple pole lamps

Where connected In series with the

primary of the

signal transformer

In series with the

primary of the

signal transformer

In series with the

secondary of the

signal transformer

Current range 0.3A on the

primary

0.3 Amp on the

primary

2.5 Amp on the

secondary side

Voltage drop across

the load ( ECR or a

indication lamp )

7 volts 9V across 9V

Voltage ratio

Primary/ Secondary

10V/7V 0.5V/9V 0.3V/9V 8/21/2020 S19 Relays and cables 169


ECR RELAY


Siemen’s ECRs

The Siemen’s ECR relays are supplied as mini groups. The mini

group comprises of a current transformer, bridge rectifier and a

neutral relay of K. 50 ‘E’ type.

There are three types of Siemen’s ECR relays

ON aspect ECR, OFF aspect ECR and UECR.

The ON aspect ECR de-energises when the main filament of a

signal lamp is fused and the auxiliary filament is intact, so as to

draw the cabin man’s attention . This helps early detection and

replacement of lamp and there by avoiding the possibility blank

signal. This consideration is not necessary for the OFF aspect.


RECR Unit

When both filaments of the signal lamp are lit, the primary voltage of the current transformer is about 3.4V at 300 mA current. The relay gets a D.C. voltage of over 7V and picks up. When the main filament of signal lamp is fused, the primary circuit current falls to about 100 mA. The relay voltage drops to less than 2V, well below its drop away value. The relay drops.

Since the drop away value of this relay is above 4.5V, it drops even when the auxiliary filament of signal lamp is fused and main filament above is lit. 8/21/2020 S19 Relays and cables 173

DECR Unit

When both filaments of the signal lamp are lit, the primary voltage of this unit transformer is about 12.5V at 300 MA current. At that time the relay gets a DC voltage of about 9.6V.

When main filament is fused, the primary current falls to about 50 MA. The relay gets a voltage of over 5V which is more than its D.A. value. Hence the relay does not drop.

When both the filaments fuse, the no load current of signal transformer, which is less than 15 MA makes the relay to drop.


Sl.no.

Description ON ECR OFF ECR

1 Current transformer voltage ratio

1 : 3 1:1

2 Amphenol terminal no’s of relay coil

1-91 1-92

3 Relay coil Resistance

64.1 64.1

4 Std contact configuration

3F/3B 3F/3B

5 PU voltage/current

App.5 V/<340 m A

App 9 v/<340 m A

6 DA voltage/current App.4V/125 m A

App 4V/125 m A 8/21/2020 S19 Relays and cables 175

SIEMENS UECR Unit

The primary of the current transformer is connected

in series with the signal lamp circuit.

Its secondary voltage is rectified by D1-D4 and

smoothened by condenser C1. This voltage is

applied to the ECR relay in series with an SCR.

The SCR switches on when its gate current is > 5

MA. Also, SCR has a constant voltage drop across it

irrespective of current through it.


UECR Unit


CT- Current Transformer

D1- D4- Bridge Rectifier

D5- To make relay slow to release

C1- Condenser -100 Mfd. Filtration of rectified PC

C2- Condenser - 0.1 Mfd

R1- Resistance = 33 K Ohms

R2- Resistance = 3.9 K Ohms to limit gate current

R3- Resistance = 10 Ohms to limit circuit current

UECR = K-50. 'B' Type relay

UECR CIRCUIT


Polarised Relay


DC Polarized Relay

It makes different contacts for different polarities of DC supply connected to it.

It works on the principle that the poles of electromagne8ts change with the direction of current.

Application –It is used in token block instruments to check line polarity when block handle is turned at the other end of the section.


Operating principle of DC Polarized Relay

In this relay, a steel strap is polarized by a permanent magnet placed behind it and is hinged between the poles of an electromagnet.

A movable contact spring called 'arm' is attached to the strap in the front.

This Arm makes with one of the two fixed contacts on either side when the relay is energized with alternate supply polarities.



Polarised relay


Polarised relay


Polarised relay

Reverse contact


Polarised relay

Norma

l

contact

Operating characteristics:

a. Rated pick up value = 21 MA

b. Resistance = 77 ohms c. Drop away value = Not less than 50% of pick up value. d. AC Immunization = 10 V AC Permitted over energisation =25ma as per SEM para

22.9.10.2 Current carrying capacity of a contact - continuous = 1 Amp for 30 sec = 2 Amp f. Contact resistance = 0.25 ohms


SIEMENS THERMO

FLASHER UNIT


Principle of operation of Thermo Flasher unit

The thermo flasher unit is used to generate a flashing

supply to give flashing indications on the panel

An oscillating mercury column enclosed in a U-shaped

glass tube gives the periodical flashing of about 60

impulses per minute.

The movement of mercury column is caused by hydrogen

gas in an interconnected glass chamber. In the lower

portion of the gas chamber, a heating element is placed.


Principle of operation of Thermo Flasher unit

When current is passed through the filament of heater, gas

expands and exerts pressure on the mercury column in one limb.

With depression of the column in one limb, the contact of the

heating element 'g/a' breaks.

The mercury column then returns to its original position by force

of gravity. Now, the heating circuit is closed again. This

procedure gets repeated and swings the mercury column

continuously till the external feeding circuit is opened. This

opens and closes the contacts b/a, c/a, d/a, e/a & f/a, alternatively,

which can be used for the required indication controls



Flasher Relay


Flasher Relay

Thermo Flasher unit


Parameters of Thermo Flasher unit

1. Coil (heating circuit input)12V D.C/A.C or 110V/220V AC

(With built in transformer).

2. Approx. power input 9W @ 12V and

during heating impulse 20W @ 110/220V.

3. Flashing frequency 60/ minute.

4.Current on contact - 6A @ 12V, 2A @ 110V & 1A @ 220V.


Track relays

Presented by P.Shakila IOS5

PLUG IN TYPE TRACK

RELAYS

1)Characteristics of relay

2)QT2

3) QTA2

4) QBAT

Factors that effect the sensitivity of relay :

a) Force of attraction

b) Effect of Air gap

c) Effect of Hysteresis

d) Transient condition

In any electro-magnetic system, the force of attraction is given by.

F B2 a

Where: B - is the flux density and a - is the cross sectional area of the particular part of the magnetic circuit.

But B is proportional to Current .So F α I2 .

This feature has got more effect on Track relay , because even a small change in current will have a great effect on the working of the relay

Force of attraction:

The difference between Pickup current and drop away currents of the relay should be as small as possible to ensure good shunting characteristics .

This can be achieved by maintaining a small air gap between core and armature

If the air gap is not available, then the residual magnetism fluxes might cause the armature to be retained when the supply is disconnected.

For this reason, residual pins are provided to ensure a definite minimum air gap in the energised position.

Effect of air gap:

Hysteresis is the property by which the flux produced lags behind the current. High hysteresis loss will increase PU time & DA time

To overcome the effect of Hysteresis the relay core is made of material having high permeability and low retentivity (i.e, low Hysteresis loss)

This reduces the difference between pick up value and Drop away value. By selecting good quality core material, Percentage release and sensitivity of the relay will be improve.

Effect of Hysteresis

The relay coil has certain amount of inductance which produces back emf during energising and de-energising of the relay.

This causes a transition in the relay current from reaching its maximum or minimum values . Due to this transition the pickup time and drop away time of relay are effected.

Transient conditions” are important so far as track relays are concerned as they effect the release time of the track relay

Transient Condition

How the percentage release & sensitivity of TR are improved

To reduce releasing time to a minimum value

• The relay iron should have low Hysteresis loss and low retentivity.

• The degree of over energization of the relay should be restricted

• Connecting a suitable external resistance in series with the relay to keep L/R ratio low.

• Use relay with minimum contacts, as they require lesser current which keeps inductance value low

• Train working safety is ensured only if the track relay of shortest length track circuit is released before a light engine running at a highest permitted speed clears it. Otherwise, the track circuit occupation may go undetected. To avoid this, a special provision has to be made in signal control circuits, wherever necessary.

QT2 Style Track Relay

• Similar in construction to line relay.

• Coil resistance: 4 Ohms and 9 ohms.

• 4 ohms relay is used for longer length track circuits and 9 ohms relay for shorter length track circuits.

• 2F/1B is to reduce load on armature, hence sensitive and can operate at low voltages.

• Back contact is used for cross protection to prevent the repeater relay from picking up in case of false feed.


• Maximum permissible excitation is 300% of the rated PU value. (Pusher spring allows higher excitation than shelf type). Minimum excitation is 125% of p.u.v

• % Release must not be less than 68%.

• Use: As TR in Non RE areas.

• 9 ohms relay: PU current: 103mA- 117mA, PU voltage: 1.5V.

• 4 ohm relay P U voltage: 0.3V to 0.5V.



QTA2: AC immunized track relay.

• In this relay, a copper slug is provided on the core at its armature end to make it immune to A.C.

• In all other respects, it is similar to QT2 relay in construction.

• Its coil resistance is 9 ohms, which can ensure A.C. immunity of not less than 50V.

• 20 ohms coil QTA2 relays are also available.

• Due to the provision of copper slug, the relay requires more DC operating power and it takes more time for its pick up and release.

QTA2: AC immunized track relay.

• Only QSPA1 relay is permitted to be used as TPR with this track relay.

• This is because an unsafe condition shall not be created during the catanery short circuit conditions, when A.C. voltage drop in a track circuit rail increases manifold, the TR may pick up under train and remain so for over 250 m sec.

• The circuit breaker in the traction power substation takes about 300 m sec. to trip.

• In this context, QSPA1 relay’s use as TPR is safer as it takes a longer time to pick up.

QTA2 AC immunized track relay.

• A/C Immunity level 50V AC rms.

• Contacts --- 2F/1B.

• Being sensitive relay its DC PU value should not change by a larger extent hence the limitation on the AC immunity, same as in shelf type.

• Max length of Track circuit is 450mtrs. (Rail voltage drop is 10V /90mtrs of track circuit).

• QSPA1 only is to be used as repeater relay with QTA2.

• 9 ohm relay: PU volts: 1.0 to 1.4V, PU current: 120mA to 140 mA.

QTA2 AC immunized track relay.

QBAT: Biased AC immunized Track Relay

• This is a track relay with an improved immunity level of 80V A.C. by the provision of a biasing permanent magnet on its core along with its copper slug.

• This biasing by initially polarizing the core strengthens its electro-magnetic flux created in the correct direction by coil current.

• This takes more AC voltage to disturb the DC working flux. • This relay also requires QSPA1 relay as its TPR for the same

reasons specified in the case of QTA2 relay. • Construction same as QBCA1 excepting for contacts. • Permanent M agnet is for biasing and also contributes to

raising AC immunity level. • Copper slug for AC Immunity.

QBAT: Biased AC immunized Track Relay.

• Contact configuration: 2F/2B.

• PU volts: 1.1 to 1.75V,

• PU current: 140mA to 175 mA.

• AC Immunity level : 80V,

• Coil resistance: 9 ohms.

• Max length of track circuit: 720mtrs and can be extended to 750mtrs by using a choke at relay end and feed end

• Maximum excitation: 235% of P.U.V only because of the flux of P.M.

QBAT RELAY

M Biasing magnet

L Copper sleeve

QBAT

Signalling cables

Presented by P.shakila IOS5


SIGNALLING CABLES

PVC insulated PVC sheathed and armoured signalling

cables to specification IRS S63 shall be used for signalling

circuits.

The conductors used shall be of copper and of approved

size.


SIGNAL CABLE LAYING PRACTICE


TYPES OF SIGNALLING CABLES

1. INDOOR CABLES 2. OUT DOOR CABLES 3. POWER SUPPLY CABLES



INDOOR CABLE OUT DOOR CABLE

POWER CABLE

INDOOR CABLES

1. Indoor cables are without armor wire 2. All the PVC insulated conductors are bunched and kept in thin

PVC insulation tubes

3. Available in 60C,40C,24C,20C &16Core cables S.

No Dia. of the conductor

Size of core Used

1 0.6 mm 60C,40,24C & 20C

Used for relay wiring

2 1 mm 60C,40,24C & 16C

Copper single stand used for high current circuits such as signal lamp circuit, point operation circuit, gate circuits, etc.,

3 0.4mm single stand

Flexible wires Copper single stand wire used for indication lamps and panel wiring.

4 16 stands 0.2mm

Flexible wires

Used for Q- Series relay wiring. 8/21/2020 S19 Relays and cables 219

1 2 3 4 5 6 7 8 9 10

Blue Red Grey Green Brown Black Yellow with

Red dots White Pink Violet

Indoor cable conductors can be numbered according to color

code as shown below:


OUT DOOR CABLES (IRS . S63)

1. These conductors used are copper conductors having equal diameter with PVC insulation.

2. All the PVC insulated conductors are bunched and kept in PVC insulation tube.

3. On the circumference of this tube, Galvanized iron rectangular or circular cross section wires called armor is provided to give the mechanical strength to protect the cable from damages.

4. On the armor PVC insulated thick tube is provided to give the more mechanical strength and good insulation resistance in addition to preventing the water entering inside the cable.

5. Sizes of conductors: 1.5 sq.mm., 2.5 sq.mm. and 4 sq.mm. 6. Cables available in 2C, 4C, 6C, 8C, 9C, 12C, 18C, 20C, 24C and 30C.


Core Color Layers

2C Red and Black

4C Blue, Black, Red and Yellow

12C Blue, Grey and Yellow Outer layer (9 conductors)

Blue, Red and Yellow Inner layer (3 conductors)

30C Blue, Grey and Yellow Outer layer (16 conductors)

Blue, Grey and Yellow Second layer (10 conductors)

Blue, Black, Red and Yellow Last layer (4 conductors)

7. Conductors bunched in the form of layers. 8. Numbering is started from outer most layers of conductors and

each layer numbering starts from Blue color, then Gray and layer end with Yellow.

OUT DOOR CABLES (IRS . S63)


CORE ARMOUR

OUTER

SHEATH

METALLIC

SHEATH

INSULATION

PAPER

CORE

INNER

SHEATH ARMOUR OUTER

SHEATH

SCREENED CABLE

UN SCREENED CABLE


Outer

Layer

1 2 3 4 5 6 7 8 9 10

Blue Grey Grey Grey Grey Grey Grey Grey Grey Yellow

Inner

Layer

10 11 12

Blue Red Yellow

1st Layer (Outer

most Layer)

1 2 - 15 16

Blue Grey Yellow

Outer Layer 17 18 - 25 26

Blue Grey Yellow

3rd Layer (Inner

Layer)

27 28 29 30

Blue Black Red Yellow

30

CORE

:


Outer

Layer

1 2 3 4 5 6 7 8 9 10

Blue Grey Grey Grey Grey Grey Grey Grey Grey Yellow

Inner

Layer

10 11 12

Blue Red Yellow

12 CORE CABLE


1st Layer (Outer

most Layer)

1 2 - 15 16

Blue Grey Yellow

Outer Layer 17 18 - 25 26

Blue Grey Yellow

3rd Layer (Inner

Layer)

27 28 29 30

Blue Black Red Yellow

30 CORE CABLE


POWER SUPPLY CABLES

1. PVC insulated screened and armored cable to IRS. S35/1970. 2. Any metallic sheathed armored cable having a cable reduction

factor of not more than 0.4 at a field strength of 87.5 to 450 v/km

3. Paper insulated lead sheathed and armored IRS. E 17/1959. 4. Conductors are alluminium & copper.


Dia. (sq.mm) Core

70 (Alluminium) Single strands 3 & 3½



25 (Alluminium) Multi strands (7) 2, 3, 3½ & 4

10 (Alluminium) Single strands 2

8 (Copper) Single strands 2

6 (Copper) Single strands 2

Cable Numbering: 01 24 (4) or 02 18 (4) or 03 24 (6) First two no’s indicates - S. No. Second two no’s indicates – Core In brackets indicates – Spare; M- main; T- tail; P- power cable

POWER SUPPLY CABLES


LAYING OF SIGNALLING CABLES

All signalling circuits are transferred to underground cables.

Only un screened cable should be used.

Screened cable already existing to be continued.

The main cables shall ordinarily be PVC insulated and armored cable to IRS S – 63.

Insulation resistance of each core shall not be less than 5 Mega ohms/km at 50 degrees.


LAYING OF SIGNALLING CABLES

PLANNING: 1. Determine number of conductors required. 2. Adequate spare conductors min. of 10% of the total conductors

used shall be provided in each cable 3. No spare conductors are required if the total number of

conductors used is three or less. 4. After deciding the size and the no. of conductors , a foot survey

along the track should be taken, as far as possible, to avoid water mains, oil pipes, drain/sewage pipes, water columns etc.,

5. Before starting the trench work approval shall be taken from P.WAY/ELECTRICAL departments.


Width of cable trench 0.46 Mtrs.

The cable laid parallel to the track normally be buried at a depth of 1 Mtrs. from ground level.

In theft prone area depth of 1.2 Mtrs. with anchoring at every 10 Mtrs.

Out side the station limits, the cable should generally be laid not less than 8 to 10 Mtrs. from the centre of the track.

With in station limits, the cable shall preferably be dug at a distance not less than 5.5 Mtrs. from the centre of the track in RE area.

TRENCH


With in station limits, the cable shall preferably be dug at a distance not less than 3 Mtrs. from the centre of the track in non- RE area.

When signalling and main telecom cables are laid in the same trench, a distance of 100 mm is to be maintained between them.

When signalling cables and LT or HT power cables are laid in the same trench, they must be separated by a row of bricks between them.

TRENCH


The bottom of the cable trench shall be levelled and sharp materials, if any, shall be got rid of. In case of soft ground, the cable shall be laid at the levelled bottom. In case, the ground is rocky, the cable shall be laid on a layer of sand of 50mm thickness deposited at the bottom of the trench.

In both the above cases, the cable shall be covered with a layer of sand or "Sifted" earth of 100 mm thickness as a protection and provide bricks on the layer and filled.

TRENCH


While cross the track

The cable crosses the track right angles.

The cable does not cross the track under points and crossings and

The cable laid in concrete or GI or PVC pipes or suitable ducts or in any other approved type.

While crossing track 1 Mtrs. below the rail flange.

Cables are to be laid with in 1Mtrs. from sleeper end, digging beyond 0.5 Mtrs. shall be done in the presence of an official from engineering department.


When cable have to cross a metallic bridge, they should be placed inside a metallic trough which may be fitted, as an anti theft measure, with sealing compound. Adequate cable length to the extent of 2 to 3 Mtrs. shall be made available at the approaches of bridges.

Cable markers shall be provided at suitable internal at diversion points.

At each end of the main cable an extra loop length of 6 to 8 Mtrs. Should be kept.

For recognizing deferent cables in case of faults etc., the cable shall be laid in an order from track side.

Telecom cable. Signal cable. Power cable.


While cross the track

ADDITIONAL PRECATIONS IN RE-AREA

1.AT OHE STRUCTURE:-

Cable depth does not exceed 0.5 Mtrs., cable trench should be 1 Mtrs. away from the OHE mast.

Cable depth exceeds 0.5 Mtrs., a minimum distance of 3 Mtrs. between the cable and the nearest edge of the OHE mast.

If it is difficult to maintain these distances, the cable shall be laid in concrete / HDPE / Ducts / any approved means for a distance of 3 Mtrs. on either side of the mast. Where so laid, the distance between the cable and the mast may be reduced to 0.5 Mtrs.


2.Sub Station and Feeding posts

As far as possible, the cable shall be laid on the side of the track opposite to the Feeding post.

The cable shall be at least 1 Mtrs. away from any metallic part of the OHE and other equipment at the Sub station which is fixed on the ground and at least 1 Mtrs. away from the Substation earthing.

In addition, the cable shall be laid in concrete or heavy duty HDPE or split RCC pipes or other approved means for a length of 300 Mtrs. on either side of Feeding post.



3. SWITCHING STATIONS

The cable shall be laid at least 1 Mtrs. away from

any metallic body of the station, which is fixed in the

ground, and at least 5 Mtrs. from the station earthing.

The distance of 5 Mtrs. can be reduced to 1 Mtrs.

provided the cable are laid in concrete pipes or

heavy duty HDPE or ducts or any other approved

means.


4. Where are independent earth is provided for an OHE structure i.e., where the mast is connected to a separate earth instead of being connected to the rail, the cable shall be laid at least 1 Mtrs. away from the earth.


INSTALLATION

Testing cable before laying : 1. Visual inspection of cable. 2. Cable shall be tested for insulation and continuity. 3. The insulation resistance of new cable shall not be

less than 200 mega ohms per km. at 20 degree centigrade.


INSTALLATION

Paying out the cable: 1. The cable drum shall be mounted on cable wheels. 2. The drum on the wheel shall be brought to one end of the trench

and laid in the trench. 3. The drum on wheel shall then be rolled along the road or track. 4. Wheel are not available, the drum shall be mounted on axle at

one end of the trench and cable payed out. 5. Cable should be carried by adequate number of men ensuring that

the cable is not damaged and no kink is formed.


Testing Of Cables for Faults

The common faults which develop on conductors of multi-core signaling cables are: i) Earth ii) Short-Circuit iii) Open -Circuit.


Earth fault develops in a conductor due to defective insulation, which allows the current, carried by the conductor to leak to the earth directly or indirectly instead of going to the apparatus to which the conductor is connected


Earth fault

Short circuit occurs when a connection or short develops due to defective insulation between two or more conductors where no connection should exist.


Open circuit: It develops if a break occurs in a conductor.


Method of Testing with a Megger

Megger used for testing signaling cables is of 500 Volts DC. For telecom cables is of 110 Volts DC. All the above mentioned common faults which develop on conductors of multi-core signaling cables can be detected by testing with a megger.


To Test for an Earth fault:

If the conductor to be tested in the use, both ends must first be disconnected from the circuit of which it forms part. One end is then connected to the megger terminal marked for line. The next step is to connect the other megger terminal E (EARTH) to a good earth. Then rotate the megger handle about 80 RPM and while doing this observe where the pointer comes to rest on the scale. If the pointer rests at ZERO, there is a full earth fault in the conductor.


To Test for an Earth fault:

If it rests at INF (INFINITY), it indicates that the insulation of the conductor is O.K. When the megger handle is rotated a voltage is generated which tries to pass a current through the conductor. No current will flow, however, if the insulation is in order as the circuit is not complete. An earth fault, however, will complete the circuit and a current will then pass through the circuit


To test for a short circuit.

The conductors if in use, must first be disconnected. Then connect them to and rotate the megger handle. It will megger be obvious from the diagram that, if there is no connection between the conductors, no current can flow, and the pointer will come to rest at INFINITY. If, however, the conductors are in contact, a circuit is formed, and the current will cause the needle to indicate ZERO.


To Test for an Open Circuit:

This test can be made in two different ways. One is made by using an earth return, and the other is made by using another conductor known to be o.k. When using an earth return, first connect one end of the conductor to the megger terminal L. Then connect the other megger terminal to good earth. The far end of the conductor should also be connected to a good earth If a second conductor is used to make the test, connect up In both cases, if the conductor under test is unbroken, a circuit is formed, and, when the megger is operated, the pointer will indicate ZERO. Should, however, the conductor be broken the pointer will indicate INIFINITY.


1

2 2

1SHORTLE

LE

E

BREAK WIRE

OROPEN CIRCUIT

LE

OPEN CIRCUIT

BREAK WIRE

OR


Testing of cable insulation

Insulation Resistance tests should be made in such a manner that safe operation of trains is not affected. While conducting the tests, it should be ensured that no unsafe conditions are set up by the application of test equipment. All conductors in signaling cables must be tested for their insulation in dry weather every year preferably during the same part of the year.



The insulation Resistance Tests should be made when conductors, cables and insulated parts are clean and dry. In addition to regular testing of the cable in dry weather, random tests in wet weather may also be carried out where considered necessary. Spare cores may be tested for insulation once a year during monsoon periods to check.



The conductors of the cables possess appreciable electrostatic capacity and may accumulate electrostatic charge. The cable conductors should be shorted or earthed to completely discharge any accumulated charge: (i) Before connecting the insulation tester while commencing the test and (ii) before the Insulation tester is disconnected when the test is completed. This is in the interest of safety of personnel and protection of equipment.


A 500V insulation tester should be used for insulation testing. The insulation resistance should therefore be recorded after the test voltage has been applied for one minute or so when the indicator of the insulation meter shows a steady reading. Any metallic sheath or metal work of any rack or apparatus case should be bonded to earth during test.



Procedure: Disconnect all cores of a cable at both ends. The disconnection may be made through links of ARA terminals if provided. Connect one terminal of the insulation tester to the conductor under test and other terminal to all the other conductors being bunched together and connected to earth.



Procedure: Connect one terminal of the insulation tester to the conductor under test and other terminal to all the other conductors being bunched together and connected to earth. Similarly, test remaining conductors of the cable one by one Insulation resistance so measured should not be less than 20 mega ohms irrespective of the length of cables. In such cases where it is less than 20 mega ohms, the periodicity of testing should be increased to twice a year.



Procedure If the insulation value is found to be less than 10 mega ohms, the cause should be investigated and immediate steps taken to repair or replace the cable to prevent any malfunctioning of the equipment and circuits. The conductors, which are showing below 05 mega ohms, should be identified and till the defects are rectified, these conductors shall not be used for any circuit. Such defective conductors shall be provided with distinctive markings at both the ends of termination for ease of identity during normal maintenance



Earth leak indicators & Earth leak protectors. The use of these devices may also be considered for modern signalling installations such as Route Relay, Interlocking, Panel Interlocking & Centralised traffic Control systems.


Proforma for Cable Testing

____________ Railway

Station ___________________

CABLE INSULATION RESISTANCE TEST SHEET

Main/Tail* Cable

1. Location: From . . . . . . . . . . . . . . . . To . . . . .. . . . . . .

. . . .

2. Cores: .

3. Size: .

4. Grade 250/440/650/110OV

5. Length:

6. Type: Unscreened/Screened

7. Insulation: PVC/Paper *

8. Date of installation/Commissioning . . . .

9. Name of the manufacturer: . . . . . . . . . . .

* Strike out whichever is not applicable.

- - - - - - -

- - - - - -

Core No. Date of Test

or Designation and whether

wet, damp or dry.

- - - - - - -

- - - - - -

Temperature:

Remarks:

Signature

These instructions are to be followed in addition to those contained in paras 614 to 618, 623 to 625, and

963/964 of the Signal Engineering Manual (Given in Annexure ‘A’)


TESTING OF SIGNALLING CABLES

Various faults develop in cable are

a) Earth faults b) Open circuit fault and c) Contact fault Methods of testing generally the following methods are

used for testing of cables. a) Megger method b) Volt meter method c) Testing lamp method Among the above megger method prefers for signalling

cable testing meggering requires a) 500 V insulation tester. b) good earthing arrangement and c) communication arrangement. 8/21/2020 S19 Relays and cables 260


Difference between Screened and Un Screened Cable

s.

no

Screened cable Unscreened cable

1 IRS specification S-35/93 IRS specification S-63/07 2 It is PVC insulated metal

sheathed armoured cable It is a PVC insulated armoured cable

3 Cable screening factor 0.4 No screeining factor 4 Manufacturing cost more Manufacturing cost less 5 No more use in future

Installation In future installation only to be used Unscreened cable


CABLE SCREENING FACTOR

If any conductor lies in the magnetic field of the main source, it reduces the induced voltage of the S&T conductor. This property has been taken advantage of in the manufacturing of cables. While the cable cores are individually insulated and provided with insulated sheathing to make them compact, one more metallic sheathing is provided over this. The entire cores and metallic sheath are then covered by an insulated overall sheathing. This metallic sheathing can be in the form of an aluminium extruded pipes or strips of Aluminium covering the cores. These type of cables are called screened Cables.



In considering the screening effect of a cable sheath one must distinguish between the voltage of the core to the sheath and voltage of the core to the earth. If the metallic sheath is insulated from earth, identical voltages are induced in the sheath and core. The voltage between them is zero. At the same time, the metallic sheath does nothing to reduce the voltage between core and earth. It is, for this purpose, earthing of cables sheath at frequent intervals is insisted upon for providing an effective screening.



To reduce the voltage in the core, the sheath must have a current flow, the field of which opposes the field induced by the current in the catenary. For it to carry such a current, the cable sheath to be a part of a circuit that is completed through the earth. A.C sheath that insulates from earth or earthed at one place only, no screening effect on the Voltage between core and earth. The induced voltage in the core reduces considerably by using screened cables. The extent by which the induced voltage is reduced is called as "Screening Factor“.


• Metal sheathed cables were used (with earthed sheaths) which provided screening effect due to induced currents in them.

Screening Factor = Voltage induced in a screened cable/ Voltage induced in an unscreened cable

typical value for a signaling cable – 0.4



Why un screened cable only used?

1. If screened cable is used cable screened factor should be 1 instead of 0.4.

2. Screened factor can’t be maintained in India.

3. To maintain screening factor 1, earth resistance required almost negligible ( less than 1 ohms ). So, it may not possible in India.



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