Railways Signaling Relays PDF

Para No. 19.6.1, 21.2.1(b) Annexure: 21-A1 Relays for Railway Signalling 1.0 Relays in General (a) Relay Working Principle: A relay is an electromagnetic device, which is used for closing or opening of an...

Para No. 19.6.1, 21.2.1(b) Annexure: 21-A1 Relays for Railway Signalling 1.0 Relays in General (a) Relay Working Principle: A relay is an electromagnetic device, which is used for closing or opening of an electrical circuit. The relay may be classified as Shelf type and Plug-In Type. Plug-in-type relays which are plugged in to prewired terminal boards. It works on electromagnetic principle. Each relay has a base electromagnet, armature, contact spring, contacts, transparent cover, and handle. It works on a low current. A non-magnetic residual pin is fixed on the inner face of armature, in all relay except magnetic latch relays. When current is applied through the coil, it sets up a magnetic flux through the bar magnet, core, L shape heelpiece and armature. 2.0 Metal to Carbon Line Relay - Non- AC Immunized Relays (a) QN1 Style Relay: This is used as internal relay for all control and detection circuit except in external circuits of AC RE area. It`s specification No-B.R.S. No: 930A.Though it is immune to 300 Volt AC 50Hz but only in emergencies can be used in RE area with protection against AC Interface (b) QS3 Style Relay: It is sensitive line relay. It works on a low current. It works on 12 V DC. It`s Specification is B.R.S. 930A. (c) QB3 relay is biased neutral line Relay: It works on 12 V DC and has a contact configuration of 4F/2B.it is a biased relay. Its Biasing stands good up to 240 Volt DC. This is confirming to BRS Specification No.930A. (d) QNN1 Style Relay: This comprises two neutral line relays whose contacts and magnets are mounted side by side with a common heel piece on a base. These two relays operate independently to each other and also have equal number of front and back contacts. It is based on BR specification 960. 3.0 Metal- Carbon - AC Immunised Q- style line relays (a) AC Immunised DC neutral line Relay: The relay design shall be inherently such that the immunisation is achieved intrinsically without use of any external means. The relay shall not make any of its front contacts when 1000 V (r. m. s) of 50 Hz AC is applied at any instant to the terminals of relay coils. The relay shall not break any of its back contacts when 300 V (r. m. s) of 50 Hz AC is applied at any instant to the terminals of relay coils. This is confirming to IRS Specification No. S60 –78. Usage: these relays are used as interface relays in Electronic Interlocking systems. (b) QNA1 Relay: The immunisation is achieved by provision of a copper slug on the core at its armature end. In all other respects, it is similar to QN1.Its Specification is BR specification no. 931A. Usage: These relays are used as external relays. (c) QBA1 Relay: This is a DC biased AC immune neutral line relay. A copper slug is provided on the core for immunisation and a permanent magnet is provided on the core for Biasing. It does not operate if 20 times of the rated voltage is applied in reverse direction. It’s specification is BR Specification No. 932 A. Chapter 21: Relay & Electronic Interlocking Page 465 of 530 (d) QBCA1 Relay: This is similar to QBA1 relay but having two heavy-duty front contacts. It can carry 30A inductive current at 110 V through its front contact. The back contact can carry 3A continuous and 2A switching current like any other relay. Its Specification is BR specification no. 943.Usage: These relays are used as Point contactor relays. (e) QSPA1 relay: Only this relay is permitted to be used as the repeater for immunised ‘Q’ series track relays (QBAT & QTA2), due to its slow to pickup character. Provision of a copper slug between the core and the heel piece behind and a magnetic shunt between the core and the armature at the front contact make this relay slow to pickup. Features of QSPA1 relay are: (i) Slow to pick up by 540 /600 milli seconds.(ii) Less slow to release by 140/200 milli seconds and immune to AC. This made to BR specification no. 933A. (f) QL1 relay: This is a magnetically latched DC line relay. This relay remains in full operated condition though the feed to the relay is cut off. This relay has two coils namely operate coil (R) and release coil (N) and a permanent magnet. This made to BR specification no. 935A.Usage : these relays are used as latch relays in block instruments etc. 4.0 Track Relays Track relays shall always be of metal to carbon contact type & normally be of plug in type, unless otherwise specially permitted. In non electrified area, the following relays shall be used: 9 ohm DC non-AC immunized (plug-in type). In electrified area, the following relays shall be used:9 ohm DC neutral, AC immunized.9 ohm DC biased, AC immunized. Double element motor type relay, operating on 83 & one third Hz in AC traction area and 50 Hz in DC traction area shall be used. Vane type relays may continue in use till replacement. Relays for track circuit provided with coded, pulsed, electronic (audio frequency or high frequency track circuit), shall be of an approved type of track/line relay or as recommended by manufacturer. (a) QT2: The construction of this relay is similar to that of a Q - Series line relay except that its contact load is reduced drastically. The relay is more sensitive and workable on a low voltage.QT2 relay has only one core and 2F - 1B contacts. The back contact is used for cross protection for TPR circuit. This has a single coil unlike the shelf type relay, which has two coils with open ends. Usage: it is used as track relay in Non-RE area. (b) QTA2: Copper slug is provided on the core to achieve AC immunity. It's pick up voltage is 1.4v and pick up current is 140 ma approximately.QTA2 relays are available in 9 Ohms coil resistance with 2F/1B contact configuration. This relay requires more D.C. operating power and it take more time to pick up and drop due to the copper slug. New Installations: This can be used Upto 450 meters track Circuit Lengths in RE Areas with Choke at both ends. ii. Existing installations: This can be used Upto 450 meters track Circuit Lengths in RE Areas with Choke at the Relay end with high traction return current of 1000 Amps and up to 350 meters track circuit length without choke at the Relay end with low traction return current of 600 amps. Usage: used as track relay in RE area. Chapter 21: Relay & Electronic Interlocking Page 466 of 530 (c) QBAT: It's pick up voltage is 1.75 V and pick up current is 175 ma approximately. This is achieved by the provision of a biasing permanent magnet on its core along with its copper slug. It has only one core and 2F-2B contacts. This can be used Upto 750 meters track Circuit Lengths with choke in RE Areas. This is made to RDSO specification. No. 84/88. Usage: it is used as track relay in RE area. 5.0 Timer Relays (a) Types & Usage of Timer Relays: These relays are used in the signaling circuits to release interlocking after certain period of time to ensure safety. Following types of Time Element Relays are in use (i) DC Thermal type (ii) Siemens Motorised Clock Work time relay (iii) Motor type (iv) Electronic type (b) DC Thermal Type Element Relay (QJ1): This type of relay employs heat operated contact associated with an ordinary DC Neutral Relay. It has a heating element (H) and a neutral line relay (R) which together energise an external line relay after a pre- set time delay. One of such type is “QJI” type relay. Features of this relay are: (i) Rated Voltage 24 V DC or 50 V DC (ii) Heat coil resistance 40 to 42 Ohms (iii) Max. Heating power 15 Watt at rated supply Voltage. The Maximum numbers of operations should be restricted to 100/day otherwise characteristics of the heating element may change. An increase of 10% in applied voltage may result in a time decrease of up to 10%.An decrease of 10% in applied voltage may result in a time decrease of up to 20%.Usage: these relays are used to count time delay in Signalling Circuits (c) Electronic Timer Relays: Fail safe Electronic Timer Relays are being used to achieve time delay either by charge, discharge method or counting by clock pulse or integrated circuits. Usage: These relays are used to count time delay 6.0 Metal to Metal Relays (a) K-50 Relays: K-50 relays are available only in group units of different sizes. Depending upon the unit size, these groups are broadly classified as: (i) Mini group (ii) Minor Group (iii) Major group. The capacities of various groups are as follows (i) Mini Group: 2 Neutral control relays, 2 Interlocked relay or ECR with power conversion unit. (ii) Minor Group: 15 Neutral (with one interlocked relay replacing two neutral relays, one contactor relay replacing four neutral relays, or one resistor or condenser fixed in place of one neutral relay in some units.(iii) Major Group (used only in RRI): Up to 30 relays space with combination of Neutral and interlocked relays, One contactor relay replacing four neutral relays space one resistor and condenser fixed in placed of one neutral relay in same group (b) Group relays in Siemens interlocking: (a) 2-Aspect Signal Group (b) 3-Aspect Signal Group (c) Shunt Signal Group (d) Universal Route Group in PI, RRI (e) Point Group for PI (f) Point Group for RRI (g) Point Chain Group for RRI (c) Non AC immunised Neutral Relays: These relays are available in 4F/4B, 5F/3B & 6F/2B contact configurations. The ohmic values of these relays are 1260 ohms for 4F/4B, 1260 ohms for 5F/3B and 1840 ohms for 6F/2B Chapter 21: Relay & Electronic Interlocking Page 467 of 530 (d) Interlocked Relays: These relays are available in 4F/4B, 5F/3B & 6F/2B contact configurations. The ohmic values of these relays are 615 ohms for all contact configuration (e) AC immunised relay (Both Top & bottom Relays): These relays are available in 5F/3B contact configuration only. The ohmic values of the relay is 1840 ohms only. (f) AC immunised relay (Top AC immunised & bottom Non AC immunised Relay): These relays are available in 5F/3B contact configuration only. The ohmic values of the top relay is1840 ohms and bottom relay is 1260 ohms only. 7.0 Metal to Metal Relays - Misc Relays (a) Double Coil Relays: These relays are commonly used as Z1WR1, Z1NWR, Z1RWR, WKR3, Z1WR, WLR in point control circuit. These relays are available in 5F/3B contact configuration only. The ohmicvalues of the top relay is 1340 ohms and bottom relay is 1590 ohms only. (b) Universal ECR: These relays are available in 3F/3B contact configuration only. The ohmicvalues of the relay is 83.1 ohms only. It is used as lamp proving relay. (c) WKR1:These relays are available in 5F/3B contact configurations. The ohmic values of these relays are 1840 ohms only. It is a part of Point minor group and Point Major group. It is used for point detection. (d) WKR2: These relays are available in 5F/3B contact configurations. The ohmic values of these relays are 1840 ohms only. It is a part of Point minor group and Point Major group. It is used for point detection. (e) WJR: These relays are available in 2F/2B contact configurations. The ohmicvalues of these relays are 1840 ohms only. It is a part of Point minor group and Point Major group. It is used to provide 10 sec time duration for point operation. (f) WR (Heavy Duty contactor Relay): These relays are available in 2F/2B contact configurations. The ohmicvalues of these relays are 60 ohms only. It is a part of Point minor group and Point Major group. It is used for point motor operation (g) Siemens Motorised Clockwork Timer: This relay works on 11 OV A.C. +/- 10%. It has a time range of 1 to 5 minutes. The time can be adjusted. Its resetting is automatic. A synchronous motor drives and switches over contacts after the lapse of preset time. If the energising circuit is prematurely interrupted, the mechanism returns to its normal position before actuating the contacts. Usage: These relays are used to count time delay. Chapter 21: Relay & Electronic Interlocking Page 468 of 530 8.0 ECR Relays (a) Relays of an approved type shall be used. (b) Plug-in type Line relays of Neutral/Polar Biased/Magnetic latch/Interlocked type rated at 24/48/60 V DC shall normally be used. Suitable type of LED Lamp proving relays (QECX-61) are used for signal LED lamps to meet with parameters to suit various LED lamps. (c ) Universal Plug-in-type, Tractive armature AC lamp proving - Metal to carbon contact Relay, as per RDSO specification STS/E/Relays/AC Lit LED Signal/09-2002 (Amdt1) & BRS- 941A shall only to be used for 110V AC LED Lamp units. (d) The important parameters of LED lamp proving relays: (i) ECR pickup current = 108 mA/AC, 50Hz. (ii) ECR Drop away current = 72 mA/AC, 50Hz. (iii) This ECR withstands for a continuous current of 250 mA/AC 50Hz. (iv) Contact configuration: 4F-4B identically in A to D rows. (v) Voltage drop across R1 and R2 is less than 10V @ 125 mA/AC (normal working current). Chapter 21: Relay & Electronic Interlocking Page 469 of 530