Relay Technology in Railway Signalling

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Questions and Answers

What is one of the main features of the DC Thermal Type Element Relay?

It uses an AC power supply for operation.

It can perform unlimited operations daily.

It operates without a heating element.

It has a heating coil resistance of 40 to 42 Ohms. (correct)

What happens to the operation time of a DC Thermal Type Relay if the applied voltage is decreased by 10%?

Operation time increases by 10%.

Operation time decreases by up to 20%. (correct)

Operation time decreases by 5%.

Operation time remains the same.

Which method is NOT used by electronic timer relays to achieve time delay?

Integrated circuits

Mechanical clockwork (correct)

Counting by clock pulse

Charge and discharge method

What is the maximum number of operations recommended for a DC Thermal Type Relay per day?

100 operations Signup and view all the answers

Which group classification is NOT used for K-50 relays?

Extra large group Signup and view all the answers

What type of electrical environment does the QT2 relay operate in?

Non-RE area only Signup and view all the answers

What is the primary function of the back contact in the QT2 relay?

To provide cross protection for TPR circuit Signup and view all the answers

What is the primary advantage of using the QTA2 relay compared to other relays?

Greater AC immunity due to copper slug Signup and view all the answers

How does the QBAT relay achieve its operational characteristics?

Through a combination of a biasing permanent magnet and a copper slug Signup and view all the answers

In what scenario can the QTA2 relay be used in RE areas?

With choke at both ends up to 450 meters track circuit length Signup and view all the answers

What is the pickup voltage of the QBAT relay?

1.75 V Signup and view all the answers

What is the main function of a relay in railway signalling?

To close or open an electrical circuit Signup and view all the answers

What is the primary purpose of the QNA1 relay?

Used as an external relay Signup and view all the answers

Which type of relay is specifically designed to be used in the control and detection circuit except in AC RE areas?

QN1 Style Relay Signup and view all the answers

What role do timer relays play in signaling circuits?

To release interlocking after a set period for safety Signup and view all the answers

Which relay operates on a low current and is immune to 300 Volt AC 50Hz in emergencies?

QN1 Style Relay Signup and view all the answers

Which relay type is designed for longer circuit lengths in RE areas?

QBAT relay Signup and view all the answers

Which characteristic distinguishes the QBA1 relay from the QBCA1 relay?

Presence of two heavy-duty front contacts Signup and view all the answers

What is the maximum continuous current that the back contact of the QBCA1 relay can carry?

3A Signup and view all the answers

What is the biasing capability of the QB3 relay?

Up to 240 Volt DC Signup and view all the answers

Which relay is specifically permitted to be used as a repeater for 'Q' series track relays?

QSPA1 relay Signup and view all the answers

How does the AC immunised DC neutral line relay function when subjected to 1000 V (r.m.s) AC?

It does not make any front contacts Signup and view all the answers

What is unique about the QNN1 Style Relay compared to other relays?

It comprises two neutral line relays operating independently Signup and view all the answers

What is a unique feature of the QL1 relay compared to other relays?

Magnetically latched and retains state without power Signup and view all the answers

Which relay type has a contact configuration of 4F/2B?

QB3 Relay Signup and view all the answers

What defines the QSPA1 relay's slow to pickup feature?

540 / 600 milliseconds for pickup Signup and view all the answers

What components are typically found in a relay assembly?

Electromagnet, armature, and contact spring Signup and view all the answers

Which type of contacts are required for track relays?

Metal to carbon contacts Signup and view all the answers

In electrified areas, which relay specifications are recommended?

9 ohm DC biased, AC immunized Signup and view all the answers

What is the ohmic value of the 4F/4B configuration for Non AC immunised Neutral Relays?

1260 ohms Signup and view all the answers

Which of the following relay configurations is available for Double Coil Relays?

5F/3B Signup and view all the answers

How many relays are used in the Major Group for RRI?

30 relays Signup and view all the answers

What is the contact configuration of AC immunised relays (Top AC immunised & bottom Non AC immunised)?

5F/3B Signup and view all the answers

Which relay is used for point detection?

WKR1 Signup and view all the answers

What is the ohmic value for the 5F/3B configuration of WKR1?

1840 ohms Signup and view all the answers

Which relay group is used only in RRI?

Major Group Signup and view all the answers

What is the standard ohmic value for interlocked relays?

615 ohms Signup and view all the answers

What is the ohmic value of the relays mentioned for point detection?

1840 ohms Signup and view all the answers

Which contact configuration is available for the WJR relays?

2F/2B Signup and view all the answers

What is the maximum time range for the Siemens Motorised Clockwork Timer?

1 to 5 minutes Signup and view all the answers

What is the drop away current for ECR relays?

72 mA Signup and view all the answers

For which voltage rating are plug-in type line relays typically used?

24/48/60 V DC Signup and view all the answers

What is the continuous current withstand rating for ECR relays?

250 mA Signup and view all the answers

Which component drives and switches over the contacts in the Siemens Motorised Clockwork Timer?

Synchronous motor Signup and view all the answers

What is the voltage drop across R1 and R2 at normal working current for ECR relays?

10V Signup and view all the answers

Study Notes

Relays for Railway Signalling

Relays are electromagnetic devices used to close or open electrical circuits.
Relay types include shelf type and plug-in type.
Relays operate on an electromagnetic principle using a base electromagnet, armature, contacts, and a cover.
Low current is used.

Metal to Carbon Line Relay - Non-AC Immunized Relays

QN1 Style Relay: Used for internal control and detection circuits (except AC areas); immune to 300V AC 50Hz in emergencies.
QS3 Style Relay: Sensitive line relay, operates on 12V DC.
QB3 Style Relay: Biased neutral line relay, operates on 12V DC, with 4F/2B configuration and biasing up to 240V DC.
QNN1 Style Relay: Two neutral line relays with shared components; operates independently; based on BR specification 960.

Metal-Carbon-AC Immunized Q-style Line Relays

AC Immunized DC Neutral Line Relay: Intrinsically immune to AC; doesn't use external means for immunization.
QNA1 Relay: AC immune, with a copper slug on the core for immunization; similar to QN1.
QBA1 Relay: DC biased AC immune neutral line relay, with a copper slug for immunization and a permanent magnet for biasing; doesn't operate with 20x rated voltage in reverse.

Track Relays

Track relays are typically metal-to-carbon contact relays, often plug-in type in non-electrified areas.
9 ohm DC non-AC immunized relays are used in non-electrified areas.
Relays for electrified areas include 9 ohm DC neutral, AC immunized, and 9 ohm DC biased, AC immunized relays.
Double element motor type relays operate at 83⅓ Hz (AC traction) or 50Hz (DC traction).
Vane type relays may continue in use.
Relays for coded, pulsed, electronic circuits may be used based on manufacturer recommendations.

Timer Relays

Timer relays are used for signal release after specified time intervals in signaling circuits.
DC Thermal Element Relays employ a heat operated contact and a neutral line relay combined with an external line relay for a pre-set delay (e.g., QJ1 relay).
Electronic Timer Relays employ charge/discharge methods or counting with a clock pulse or integrated circuits for time delay implementation.

Metal to Metal Relays

K-50 relays are available in various sizes (mini, minor, major) with different capacities for neutral control, interlocked relays or power conversion units.
Group relays are used in Siemens interlocking systems (2-Aspect, 3-Aspect, Shunt, Universal Route and Point groups).

Other Relays (with specific parameters)

QBCA1 Relay: Heavy-duty front contacts, carrying 30A inductive current.
QSPA1 Relay: Slow to pick up and release, magnetic shunt for specific use in 'Q' series track relays.
QL1 Relay: Magnetically latched DC line relay with two coils (operate and release) and a permanent magnet.
QT2 Relay: Similar to Q-series line relays but with reduced contact load for low voltage operation.
QTA2 Relay: Copper slug for AC immunity; 9-ohm coil resistance; higher DC operating requirements for pick up.
QBAT relay: with biasing magnet and copper slug; used to detect track points for relays for use in rail road areas.
Other relays such as Double Coil Relays (Z1WR1, Z1NWR, ...), Universal ECR, WKR1, WKR2, WJR, WR., and Heavy Duty Contactors with specific configurations, parameters and functions.

ECR Relays

Approved type ECR relays are used.
Plug-in type relays may be Neutral/Polar Biased/Magnetic Latch/Interlocked types with 24/48/60V DC ratings, appropriate for LED lamps.

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Description

Test your knowledge on relay technology specifically used in railway signalling systems. This quiz covers various types of relays including non-AC immunized and metal-carbon relays, focusing on their operation principles and applications. Perfect for those studying electrical engineering or railway technology.