Relays For Railway Signaling

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TEACHING NOTES ON RELAYS

SIGNAL & TELECOMMUNICATION TRAINING CENTRE, BYCULLA, MUMBAI ( I S O 9001-2000 CERTIFIED )

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CONTENTS

PAGE NO.

1. INTRODUCTION

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2. Axle Counter

04

3. Components of the system

04

4. Basic function

07

5. Installation procedure.

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6. Cable connection

11

7. Power Supply Arrangements.

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8. Initial adjustment and commissioning

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9. Adjustment of wheel dip

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10. Testing of the system working

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11. Typical failure and trouble shooting

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12. Isolation of defective card

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13. Input and output voltages of each card

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14. Universal axle counter

31

INTERMEDIATE BLOCK SIGNALLING 1. INTRODUCTION

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2. Requirement of IBS

44

3. Use of axle counter for IBS

46

4. Resetting Procedure

47

5. Description of Relays and Circuitry

49

6. Power Supply Arrangement for IBS

54

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7. RELAY: A relay is an electromagnetic device, which is used to open or close electrical circuits. It is so called because it relays information from one circuit to another circuit. CLASSIFICATION OF RELAYS: Relays may be classified into various ways depending upon the following factors. 1. Type of mounting – Shelf type and plug in type. 2. Supply used – DC relay and AC relay 3. Contact arrangement - Proved and non-proved. 4. Application – Track relay, Line relay and special relays. DC RELAYS: DC Relay works on DC current. DC NEUTRAL RELAY: A neutral relay is one which operates irrespective of direction of current,. It is so called because it is magnetically neutral. DC SHELF TYPE RELAY: (As shown in fig.) PRINCIPLE OF WORKING: principle.

DC neutral relay works on electromagnetic

Each relay has two coils, core, Yoke, armature contacts and

binding post. When current is applied through the coil, it sets up magnetic flux through the core, yoke and armature. This flux causes armature to get attracted towards the pole face. Armature picks up and front contact closes. When current is interrupted magnetic flux collapses causing armature to drop due to its gravity and front contact opens. PLUG IN TYPE RELAY: Plug in type relays, which are plugged into prewired terminal board. The relay may be proved type (metal to metal) and nonproved type (metal to carbon) USAGE:

The relays are used to control signaling circuit and signalling

apparatuses. The relay also protects the signaling equipment.

4 DIFFERENCE BETWEEN SHELF TYPE AND PLUG IN TYPE RELAYS

SN.

SHELF TYPE

PLUG IN TYPE

1.

These are heavy and large

These are light and compact

2.

These occupy more space

These occupy less space

3.

Their replacement takes more Their replacement is quick and easy. time

4.

Controlled circuit must be Controlled circuit need not be tested tested

before

putting

replaced relay to use 5.

a after replacing the relay as the wiring does not get dislocated.

No coding arrangement is Some coding is needed on the relay to needed in the relay

avoid inter changeability with that of different contact position.

TRACK RELAYS AND LINE RELAYS The relays, which are directly connected to the track/rail to detect its occupation, are called track relays. The relays, other than track relays, which are connected to supply lines through necessary controls, are called line relays. TRACK RELAY

SN. 1.

LINE RELAY

The relay directly connected Other than track relay with track relay

2.

Functions with less or more Functions either with normal supply current

3.

voltage or with no supply at all.

More sensitive,% age release Comparatively low percentage release should be high

4.

For front contact non fusible Not necessary contact are necessary

5.

Less nos. of contacts due to These can have more contacts due to low power operation.

sufficient power application.

5 PARAMETERS OF SHELF TYPE TRACK & LINE RELAYS SN. FEATURE

LINE RELAY

TRACK RELAY

1.

Normally 12 VDC

Min. 125% of Relay PU

Working Voltage

2.

Max. 250% of relay PU

Coil

Two coils each of 500 ohm. Two coils each of 4.5

Resistance

1000 ohms when coils are ohms. 9 ohms when coils connected in series and are connected in series 250 ohms when coils are and 2.25 ohms when coils

3.

Contact

4.

Contact

connected in parellel

are connected in parellel

4F/B, and 6F/B

2F/B, 2F 2F/B, 4F/B

3 amps.

3 amps.

5 amps.

5 amps.

3 amps.

3 amps.

50%

68%

300 VAC

50 VAC

current rating (a) For front (b) For 30 sec. (c) For back 5.

Minimum% Release

6.

AC immunity of relay

6 Initial Pick up current for Track Relay:

Relay

2F/B

2F 2F/B

4 F/B

Resistance Min

Max.mA Min

mA

mA

MaxmA Min.mA Max.mA 9 ohm AC immune.

9 ohms

37

39

39

41

44

49

Relay min

2.25 ohm

74

78

78

82

88

98

66mAmax 72 mAmax

For line relay

Coil Resistance Max.

Max.

Max.

250 ohms

10.5 ma 12 ma 14.0 ma

1000 ohms

5.25 ma 6 ma

7.0 ma

IMPORTANT DEFINITIONS: 1. Non-fusible Contacts: A pair of contact in which one contact element comprises of non-fusible material, which present practically no risk of welding of contact. 2. Carbon Contact: “Carbon” in the expression “carbon to metal contact” is used as a general term covering graphite and compound and mixture of carbon and metal. Contact resistance should not be more than 0.2 ohms. 3. Metal Contacts: Metal in expression “metal to carbon” “metal to metal” is used as general term covering the use of silver, silver cadmium oxide, tungsten platinum or any other suitable material to an approved specification. Contact resistance should not be more than 0.05 ohms

7 4. Front Contact: That contact which is made with the arm contact when the relay is energized. 5. Back Contact : That contact which is made when relay is de-energized. 6. Arm Contact (or Armature Contact) : That contact which is movable part of the pair of contact and makes with front contact when relay is energized and with back contact when the relay is de-energized. Dependent Contact:

The condition in which a movable arm contact

connects a front contact when the relay is energized and the same arm contact connects to a back contact when the relay is de-energized.

Independent Contact: The arrangement in which the Arm contact connects to either a front or a back contact but not to both.

Pick up Value: the value of current or ampere-turns, which is just sufficient to close all the front contact of relay under specified condition. Drop Away Value: The value of current or ampere-turn at which all the front contacts of the relay get open under specified condition. % Release: It is ratio of DA value to pick up value. % Release = DA X 100 PU

8 Proved Type Relay: Means a relay having metal-to-metal contacts. The relays are called proved type since in this relay it is ensured that the release of these relays after each previous operation is proved before any function is controlled through their operated contacts. Non Proved Type Relay : Means a relay having metal to carbon contacts as front contact. These are used for controlling vital circuits. Polarized relay: It works on Dc supply. This relay is sensitive to the direction of current and makes different sets of contacts for different direction of current flowing though the coil. Working Principle: a permanent magnet is placed in between the pole faces of electromagnet. In the center position of the magnet, the flux divides equally on both side and there is no force of attraction towards any side. When the coil is energized the electromagnetic flux causes a variation in the amount of flux on either side of armature. In one side flux is strengthened and other side weakened and armature is attracted on any one side depending upon the polarity of supply. When (+) on R1 (-) on R2 the normal contacts make (-) on R1 (+) on R2 the reverse contacts make. Operating Characteristics of IRS 31-80 Relay 1. Coil Resistance – 77 ohms (38.5 ohm + 38.5 ohm) 2. Pick up current (15ma to 18 ma) 3. Rated current – 25 ma 4. Contact gap – 1.5 mm. Use: used in Non RE and RE area in B/Instt.

9 ‘Q’ Style Relay (Plug in type) These are miniature non-proved/proved plug in type relays Q’ Style Relay: is a non-proved type relay Special Feature: 1. Non proved type, independent contact, relay 2. Plug and socket type connection between relay base and relay. Board. 3. Plug board for all ‘Q’ type relays is standard. 4. The line relay is provided with max. 16 nos. of contact (with different contact combinations) 5. The track relay is provided with max. 2F contacts 6. Pre-wiring facilities are available for each type of relay, Relay replacement is easy. 7. All relays are provided with registration device with specified coding combination to prevent plugging of wrong relay. 8. Armature is biased by helical spring. 9. A retaining clip is provided to hold the relay firmly in its plug board. 10. A gasket is provided to make the relay dust proof and waterproof. OPERATING CHARACTERISTICS OF SOME MOST COMMONLY USED Q1 STYLE RELAY. SN. Description

1.

Contact

Rated

arrangement

voltage

12F.4B,

24v DC

For indoor and outdoor ckt in

8F.4B,

400

non RE area and Indoor ckt.

6F.6B,

ohms

in RE area

12F.4B,

24v DC

For external ckt in RE area

DC Neutral

8F.8B,

195

Relay

8F.4B

ohms

Neutral Line

Style

QN1

Relay

Usage

8F.8B 2.

AC-immunized

QNA1

10 3.

Magnetically

QL1

Latch Relay

8F.6B,

24v DC

11F.4B

PU-145

IRS push-

ohms

button block

TD-680

TGTR/TCFR

ohms 4.

Lamp Checking

QEC1

4F.2B

1 amp

4.5 Ohms

Relay 5.

Thermal time

For lamp proving

QJ1

2F.1B

24 v DC

relay

Thermal 43

For time delay

ohms

ckt. 30 sec to

Neutral 380

120 sec.

Ω 6.

7.

Biased AC

QBCA1

2F(HD).4B

24 v DC

208 ohms

Point m/c

immunized

control in RE

contactor relay

area

Slow pick up AC

QSPA1

8F.4B

24 v DC

195 ohms

immunized line

Repeater of QTA2 & QBAT

relay 8.

DC neutral

QS3

4F.4B

12 v DC

1000 ohms

sensitive line

In place of shelf type relay

relay 9.

DC Track Relay

10.

AC Immunized Track Relay

QT1

2F

0.5 v DC

4 ohms

In non RE area

QTA2

2F.1B

1.4 v DC

9 ohms

In RE area up to 450m

T/Ckt. length 11.

ACI biased DC track relay

QBAT

2F.2B

1.75 v

9 ohms

up to 750 mtrs.

11 K.50 Relays (METAL TO METALPLUG IN RELAYS) This relay comes in category of proved type relay.

These relays are

manufactured by Siemens’ India Limited under code K.50 Special Features: 1. All movable contacts are rigidly coupled to ensure simultaneous making and breaking of contact. 2. Double break series contact arrangement provided ensures high switching speed and more gap between the contact. 3. Contacts are designed to have self-cleaning feature. Characteristics: 1. Coil Resistance – 1260 ohms to 1840 ohms 2. Rated voltage – 24v DC, 60 v DC 3. Operating Power – 1.3 watt to 2.5 watt 4. Max. Nos. of contact – 8 5. Contact combination – 4f/4B 5F/3B 6F/2B 6. Max. Switching contact current – 2A 7. Max. Continuous load of closed contact – 5A 8. Pick up time – 25 to 60 sec. 9. Drop Away time – 7 to 15 m sec. Contact Numbering : Relay Base Pin numbering can be seen in figure. K.50 Inter locked Relay: This is also known as latch relay consist of two K.50 neutral relay arranged one above the other on a common base plate. The armature of the relay being made interdependent by an additional mechanical latching device such that one relay in its resting position latches the other in the operating position. In normal condition of latch the bottom relay armature is latched in its operated position.

12 In reverse condition of latch the top relay armature is latched in its operated position. Coil Resistance – 615 ohms. Max. Nos. of contact – 8 K.50 ’E’ Relay: (Lamp proving Relay) K50 ‘E’ relay is a special relay for proving that the signal lamp at site is lit or not. The characteristics of the K.50 ‘E’ type relay are different for proving the Red Aspect, and green/yellow double yellow aspect. Junction type route indicator with lamp in series, junction route indicator with lamp in parallel and multiple route indicator. Coil Resistance -

64.1 OHM

Max. No. of Contacts

-

6 Nos.

Contact Combination

-

3F/3B

-

5F/1B in case of UECR.

K-50 relays are available in-group or one relay with a current transformer. Maintenance of K-50 Relay:

K.50 Relay does not require periodical

maintenance. Adjustment of contact or contact spring should not be done only contacts can be cleaned when any failure occurs.

13 Important symbols of K.50 Relays Neutral Relay Coils common relay

Track repeater relay

relay controlling a signal

Locking relay for signal

Signal lamp checking relay

relay controlling a point

relay controlling a route

relay controlling a track

Locking relay for point

Locking relay for route

Point detection relay

Route checking relay

Normally closed contact of a normally dropped neutral relay (or a back contact). Normally open contact of a normally dropped neutral relay (or a front contact). Normally closed contact of normally picked up relay (or a front contact). Normally open contact of a normally picked up relay (or a back contact).

14 AC IMMUNISED RELAY AC immunized relays are used in 25 KV AC electrified area. AC immunization is done by means of two copper slug on core near pole face. A magnetic shunt between the cores above the copper slug. PROCESS: induced current in copper slugs oppose the alternating flux, most of alternating flux diverted through magnetic shunt. Flux through air gap is not sufficient to pick up the relay AC IMMUNISATION LEVEL: 1. DC shelf type line relay

300 V AC

2. DC shelf type Track relay 50 V AC 3. DC polarized relay

10 V AC

4. QNA1

300 v AC

5. QTA2

50 V AC

6. QBAT

80 v AC

15 AC RELAYS The AC relay works on AC supply: Principle of Working: AC relay works on the principle of Induction motor. Magnetic circuit completes through core and vane.

When any current

carrying conductor is placed in a magnetic field it experiences a force. In AC relay the armature is called vane it is made of aluminum when the relay is energized the vane rotates. To produce a torque to rotate the vane two fluxes with a phase difference between them is required. These two fluxes produce eddy currents in the vane. Flux Ø1 produce eddy current I1 Flux Ø2 produce eddy current I2 Ø1 interacts with I2 & produce torque T1 Ø2 interacts with I1 & produce torque T2 Resultant of T1 and T2 rotates the vane Using two coils and feeding them AC voltage with phase difference achieve two fluxes with phase difference. The phase difference between two voltages is achieved by 1. In case of single-phase supply – Feeding one coil directly and another coil through a condenser/reactance. 2. Design the coil with different power factor. In case of 3Φ or different supply. 1. By feeding the coil with different phase of 3 phases supply. 2. By feeding the coil with different source of supply. The two coils are called Local coil and control coil local coils are fed directly and control coil through reactance/condenser etc.

16 Types of AC Relay

Single Element Relay Used as only line relay

1. 2. 3. 4. 5.

Motor type double coil Double element relay Use only for Track relay it is double coil relay used for both track and line relay

Single Element Relay Source of supply is only one No. of coil may be one or two Phase angle is low Less torque Designed to work as line relay

6. Can give only two positions

Double Element Relay 1. Different source of supply. 2. Nos. of coil are two 3. Phase angle is high 4. More torque 5. Designed to work as track and line relay. Designed to give two as well as three positions.

Motor type AC Track relay (Siemens make) Contact 2F/2B Frequency 50 Hz 83 1/3 Hz

Local Voltage 130 165

Control Voltage 18.5 V 22.2 V

17 TIME ELEMENT RELAY In signalling, for the purpose of safety, a time delay is require to be maintained between initiation and actual operation of certain circuit / equipment to achieve the time delay, time element relay is used. Types of Time element Relay 1. DC Thermal Type. 2. DC Clock Work Type 3. Motor Type 4. Electronic Type 1. DC Thermal Type (QJ1): - this is a thermal time element relay. It has a heating element and a neutral relay, which together energizes an external time relay after a pre-set time delay. Circuit is shown in figure. 1. Rated voltage – 24 v DC 2. Heating Coil Resistance – 40 ohms 3. Neutral Time Relay – 400 ohms 4. Time – 30/60/120 sec. DC clock work Type: Working voltage – 60 v DC Time – 1 minute to 3 minutes. Motor Type Timer: Working voltage – 110 v AC Time: 1 to 5 minutes. Electronic Type Timer: Working voltage – 12v, 24v, or 60 v DC Time: 60sec, 120sec, 180 sec.

18 SLOW ACTING RELAY Slow acting relays are so called because their operation is delayed for a period of a few seconds or milli seconds to keep circuit controlled by them live even after their own feed is cut off. This is necessary to maintain certain operational sequences. Slow acting relays are classified as 1. Slow to pick up and slow to release. 2. Slow to pick up relay. 3. Slow to release relay. Slow to pick up and slow to release: to make slow to pick up and slow to release relays, Copper sleeves are provided on the core of relay. Copper sleeve

Slow to Pick Up Magnetc shunt

Slow to release relay: Relays are made slow to release by following methods 1. By connecting a diode in reverse biased.

RELAY

2. By connecting a condenser across relay \/\/\/\/\/\ RELAY

3. By proving the front contact of relay in series of condenser. \/\/\/\/ RELAY

19 Flasher Relay: These relays are normally used for giving flashing indications. When supply is connected its armature makes normal and reverse contacts alternately. The contacts when connected with indication circuit the indication will flash. Contactor Relay:

These relays having heavy-duty contacts are used to

control high current for point machines etc to reduce the Arc due to high breaking current permanent or electromagnets are used near heavy-duty contact for spark quenching.

20 Maintenance Check: During Maintenance visit relays should be checked visually for the following. 1. There is no loose connection on the terminals. Plug in relays are fitted tightly and the sealing is intact. 2. Metal contacts are not blackened due to arcing 3. There is no pitting of carbon contacts. 4. No foreign materials are inside the relay. 5. There is no rusting or sulphation on the parts. 6. Removing the transit lock screw, hole has been closed by dummy screw fitting, before connecting a shelf type relay in circuit. 7. Relays are not due for POH. 8. Track relay drops properly with 0.5 ohms TSR. 9. Over energisation is not more than 250 % of its PU value. As per SEM: 01. All vital relays should be inspected visually once in every two and three years for track and line relays respectively in following respect. a. Movement of Armature and current carriage. b. Wiping of contacts arcing of contacts if any c. Pitting or charring of contacts. d. Dust on contact. e. Electro plating f. Corrosion rusting of contact. g. Presence of fungus h. Charring of cover near contacts i.

Corrosion of label.

j.

Presence of seal.

Overhauling:

Track relay:

Track relay of all type should be overhauled after every 10 to 12 years. Shelf type line relays: Shelf type line relays shall be over haled after every 15 years All other non-proved type relays, when removed from service after failure.

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