Podcast
Questions and Answers
What is the primary function of a relay in electrical circuits?
What is the primary function of a relay in electrical circuits?
- To store electrical energy
- To close or open electrical circuits (correct)
- To amplify electrical signals
- To regulate voltage levels
Which of the following is a classification of relays based on their mounting?
Which of the following is a classification of relays based on their mounting?
- Polar Biased type
- Neutral type
- Magnetic latch type
- Shelf type (correct)
For which type of circuits is the QN1 Style Relay primarily intended?
For which type of circuits is the QN1 Style Relay primarily intended?
- High voltage power circuits
- External circuits in AC RE areas
- Internal control and detection circuits outside AC RE areas (correct)
- All external circuits
What operational voltage is specified for the QS3 Style Relay?
What operational voltage is specified for the QS3 Style Relay?
What is a distinctive feature of the QB3 relay concerning its operational nature?
What is a distinctive feature of the QB3 relay concerning its operational nature?
Which relay type is specifically mentioned for usage as interface relays in Electronic Interlocking systems?
Which relay type is specifically mentioned for usage as interface relays in Electronic Interlocking systems?
What is the primary reason for the QSPA1 relay's slow pick-up characteristic?
What is the primary reason for the QSPA1 relay's slow pick-up characteristic?
Under what conditions is a QTA2 track relay, intended for RE areas with choke at both ends, suitable for new installations concerning track circuit lengths?
Under what conditions is a QTA2 track relay, intended for RE areas with choke at both ends, suitable for new installations concerning track circuit lengths?
For a DC Thermal Type Element Relay (QJ1), what is the consequence of a 10% increase in applied voltage on its time delay characteristic?
For a DC Thermal Type Element Relay (QJ1), what is the consequence of a 10% increase in applied voltage on its time delay characteristic?
Siemens Motorised Clockwork Timers are designed to operate within what AC voltage range?
Siemens Motorised Clockwork Timers are designed to operate within what AC voltage range?
Consider a scenario where a QN1 Style Relay is erroneously deployed in an external circuit of an AC RE area without supplementary AC interface protection. Given the relay's inherent immunity and assuming a sinusoidal AC interference voltage with an RMS value of 250V at 50Hz is persistently present across the relay coil, what is the most probable operational outcome, disregarding transient phenomena?
Consider a scenario where a QN1 Style Relay is erroneously deployed in an external circuit of an AC RE area without supplementary AC interface protection. Given the relay's inherent immunity and assuming a sinusoidal AC interference voltage with an RMS value of 250V at 50Hz is persistently present across the relay coil, what is the most probable operational outcome, disregarding transient phenomena?
A railway signalling engineer is tasked with selecting a relay for a DC track circuit application in a non-electrified zone, prioritizing minimal operational current draw. Considering the QS3 Style Relay and QB3 relay, and given that both are rated for 12V DC operation, but the QB3 is a biased neutral relay with a 4F/2B contact configuration, while QS3 is a sensitive line relay, which relay would inherently exhibit a lower steady-state current consumption under normal operating conditions, assuming all other factors are equal?
A railway signalling engineer is tasked with selecting a relay for a DC track circuit application in a non-electrified zone, prioritizing minimal operational current draw. Considering the QS3 Style Relay and QB3 relay, and given that both are rated for 12V DC operation, but the QB3 is a biased neutral relay with a 4F/2B contact configuration, while QS3 is a sensitive line relay, which relay would inherently exhibit a lower steady-state current consumption under normal operating conditions, assuming all other factors are equal?
In the context of AC Immunised DC neutral line relays, specifically the QNA1 Relay, the provision of a copper slug on the core at the armature end is crucial for immunisation. If, during maintenance, a QNA1 relay is erroneously replaced with a structurally identical QN1 Style Relay in an Electronic Interlocking system interface, and subsequently subjected to a common mode AC interference of 800V (r.m.s.) 50Hz, what would be the most immediate and critical consequence?
In the context of AC Immunised DC neutral line relays, specifically the QNA1 Relay, the provision of a copper slug on the core at the armature end is crucial for immunisation. If, during maintenance, a QNA1 relay is erroneously replaced with a structurally identical QN1 Style Relay in an Electronic Interlocking system interface, and subsequently subjected to a common mode AC interference of 800V (r.m.s.) 50Hz, what would be the most immediate and critical consequence?
Consider a QBCA1 Relay employed as a point contactor relay. Given its specification of carrying 30A inductive current at 110V through its front contacts and 3A continuous, 2A switching current through back contacts, what is the maximum permissible inrush current duration for an inductive load connected to its front contacts, assuming the steady-state current after inrush is 25A, and the relay must operate reliably without contact welding?
Consider a QBCA1 Relay employed as a point contactor relay. Given its specification of carrying 30A inductive current at 110V through its front contacts and 3A continuous, 2A switching current through back contacts, what is the maximum permissible inrush current duration for an inductive load connected to its front contacts, assuming the steady-state current after inrush is 25A, and the relay must operate reliably without contact welding?
A QSPA1 relay, designed as a repeater for 'Q' series track relays, is characterized by its slow pick-up time (540/600 ms). If this relay is inadvertently replaced with a standard Q-series neutral relay with a typical pick-up time of 50 ms in a critical signalling circuit, what is the most hazardous potential consequence in terms of system safety and functionality?
A QSPA1 relay, designed as a repeater for 'Q' series track relays, is characterized by its slow pick-up time (540/600 ms). If this relay is inadvertently replaced with a standard Q-series neutral relay with a typical pick-up time of 50 ms in a critical signalling circuit, what is the most hazardous potential consequence in terms of system safety and functionality?
In a track circuit employing a QTA2 relay in a RE area with chokes at both ends, designed for track circuit lengths up to 450 meters, what is the most critical parameter that necessitates a reduction in the maximum permissible track circuit length to 350 meters if the choke is only present at the relay end, and the traction return current increases to 1000 Amps, compared to a scenario with 600 Amps return current without a choke at the relay end for the same 350m limit?
In a track circuit employing a QTA2 relay in a RE area with chokes at both ends, designed for track circuit lengths up to 450 meters, what is the most critical parameter that necessitates a reduction in the maximum permissible track circuit length to 350 meters if the choke is only present at the relay end, and the traction return current increases to 1000 Amps, compared to a scenario with 600 Amps return current without a choke at the relay end for the same 350m limit?
For a DC Thermal Type Element Relay (QJ1), a 10% decrease in applied voltage is stated to potentially result in a time delay decrease of up to 20%. If a QJ1 relay, nominally operating at 24V DC, experiences a voltage drop to 21.6V DC (a 10% decrease), and its original calibrated time delay was 10 seconds, what is the plausible range for the new time delay, considering the non-linear relationship between voltage and thermal relay timing?
For a DC Thermal Type Element Relay (QJ1), a 10% decrease in applied voltage is stated to potentially result in a time delay decrease of up to 20%. If a QJ1 relay, nominally operating at 24V DC, experiences a voltage drop to 21.6V DC (a 10% decrease), and its original calibrated time delay was 10 seconds, what is the plausible range for the new time delay, considering the non-linear relationship between voltage and thermal relay timing?
Siemens Motorised Clockwork Timers are specified to operate on 110V AC +/- 10%. If such a timer, calibrated for a 3-minute delay at exactly 110V AC, is subjected to a sustained undervoltage of 99V AC, what would be the most likely effect on its time delay characteristic, considering the operational principle of synchronous motors and potential non-linearities at voltage extremes?
Siemens Motorised Clockwork Timers are specified to operate on 110V AC +/- 10%. If such a timer, calibrated for a 3-minute delay at exactly 110V AC, is subjected to a sustained undervoltage of 99V AC, what would be the most likely effect on its time delay characteristic, considering the operational principle of synchronous motors and potential non-linearities at voltage extremes?
Considering K-50 relays classified into Mini, Minor, and Major groups, with a Major group accommodating 'Up to 30 relays space with combination of Neutral and interlocked relays,' and a Minor group accommodating '15 Neutral,' what is the maximum possible number of Interlocked relays that could theoretically be accommodated in a Major group K-50 relay unit, assuming optimal configuration and only considering the stated 'Up to 30 relays space' limit?
Considering K-50 relays classified into Mini, Minor, and Major groups, with a Major group accommodating 'Up to 30 relays space with combination of Neutral and interlocked relays,' and a Minor group accommodating '15 Neutral,' what is the maximum possible number of Interlocked relays that could theoretically be accommodated in a Major group K-50 relay unit, assuming optimal configuration and only considering the stated 'Up to 30 relays space' limit?
For Non AC immunised Neutral Relays, available in 4F/4B, 5F/3B, and 6F/2B contact configurations, the ohmic values are specified as 1260 ohms for 4F/4B and 5F/3B, and 1840 ohms for 6F/2B. What is the most likely underlying engineering rationale for the 6F/2B configuration exhibiting a higher ohmic value compared to the 4F/4B and 5F/3B configurations, assuming all relays are designed for the same nominal operating voltage?
For Non AC immunised Neutral Relays, available in 4F/4B, 5F/3B, and 6F/2B contact configurations, the ohmic values are specified as 1260 ohms for 4F/4B and 5F/3B, and 1840 ohms for 6F/2B. What is the most likely underlying engineering rationale for the 6F/2B configuration exhibiting a higher ohmic value compared to the 4F/4B and 5F/3B configurations, assuming all relays are designed for the same nominal operating voltage?
What is the consequence of applying 20 times the rated voltage in reverse direction to a QBA1 relay?
What is the consequence of applying 20 times the rated voltage in reverse direction to a QBA1 relay?
Which feature of the QSPA1 relay contributes to its slow pick-up characteristic?
Which feature of the QSPA1 relay contributes to its slow pick-up characteristic?
What is the maximum permissible inrush current duration for an inductive load connected to the front contacts of a QBCA1 relay, assuming the steady-state current is 25A?
What is the maximum permissible inrush current duration for an inductive load connected to the front contacts of a QBCA1 relay, assuming the steady-state current is 25A?
What is the most probable effect on the time delay of a Siemens Motorised Clockwork Timer, calibrated for a 3-minute delay at 110V AC, if subjected to a sustained overvoltage of 121V AC?
What is the most probable effect on the time delay of a Siemens Motorised Clockwork Timer, calibrated for a 3-minute delay at 110V AC, if subjected to a sustained overvoltage of 121V AC?
How does the construction of QT2 relays differ from Q series line relays to accommodate low voltage operation?
How does the construction of QT2 relays differ from Q series line relays to accommodate low voltage operation?
What is a critical consideration when using a QTA2 relay in new installations within RE areas concerning track circuit lengths?
What is a critical consideration when using a QTA2 relay in new installations within RE areas concerning track circuit lengths?
What is indicated by the ohmic value of 615 ohms for interlocked relays in railway signaling circuits?
What is indicated by the ohmic value of 615 ohms for interlocked relays in railway signaling circuits?
What is the significance of using track relays made of metal to carbon contact type in railway signaling?
What is the significance of using track relays made of metal to carbon contact type in railway signaling?
How do electronic timer relays achieve time delay in railway signaling circuits?
How do electronic timer relays achieve time delay in railway signaling circuits?
What benefit do Siemens Motorised Clockwork Timers provide in railway signaling systems?
What benefit do Siemens Motorised Clockwork Timers provide in railway signaling systems?
Flashcards
Relay
Relay
An electromagnetic device used for closing or opening an electrical circuit.
QN1 Style Relay
QN1 Style Relay
An internal relay used for control and detection circuits with protection against AC interference.
QS3 Style Relay
QS3 Style Relay
A sensitive line relay that operates on low current and 12V DC.
QNN1 Style Relay
QNN1 Style Relay
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AC Immunised DC Neutral Line Relay
AC Immunised DC Neutral Line Relay
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QBA1 Relay
QBA1 Relay
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QBCRA1 Relay
QBCRA1 Relay
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QL1 Relay
QL1 Relay
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Electronic Timer Relay
Electronic Timer Relay
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Timer Relays
Timer Relays
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DC Thermal Type Element Relay (QJ1)
DC Thermal Type Element Relay (QJ1)
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K-50 Relays
K-50 Relays
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Non AC immunised Neutral Relays
Non AC immunised Neutral Relays
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Siemens Motorised Clockwork Timer
Siemens Motorised Clockwork Timer
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parameters of LED lamp proving relays
parameters of LED lamp proving relays
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Track Relays Main Usage
Track Relays Main Usage
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Double Coil Relays
Double Coil Relays
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Universal ECR
Universal ECR
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Study Notes
- A relay is an electromagnetic device used to open or close an electrical circuit
- Relays can be shelf or plug-in type, the latter plugging into prewired terminal boards
- Relays operate using electromagnetic principles and include a base electromagnet, armature, contact spring, contacts, transparent cover, and handle
- Current flow through the coil creates magnetic flux passing through a bar magnet, core, L-shape heelpiece, and armature
- Most relays have a non-magnetic residual pin on the inner face of the armature, except magnetic latch relays
Metal to Carbon Line Relay - Non-AC Immunized Relays
- QN1 Style Relay is used as an internal relay for all control and detection circuits, except in external AC RE area circuits
- It's specification No-B.R.S. No: 930A and is immune to 300 Volt AC at 50Hz, used in emergencies in RE areas if AC interface protection is present
- QS3 Style Relay is a sensitive line relay, it operates on a low current at 12V DC and the Specification is B.R.S. 930A
- QB3 relay is biased neutral line relay, the relay operates on 12V DC with a 4F/2B contact configuration and its biasing works up to 240V DC, confirming to BRS Specification No.930A
- QNN1 Style Relay comprises two neutral line relays with contacts and magnets mounted side by side on a common heel piece and the relays operate independently with an equal number of front and back contacts and it is based on BR specification 960
Metal-Carbon - AC Immunised Q-style line relays
- The relay design should intrinsically achieve immunization without external means
- Should not make any of its front contacts when 1000V (r.m.s) of 50 Hz AC is applied, or break any back contacts when 300V (r.m.s) of 50 Hz AC is applied
- Confirms to IRS Specification No. S60 -78 and are used as interface relays in Electronic Interlocking systems
- QNA1 Relay immunization achieved by a copper slug on the core at its armature end, similar to QN1 and specification is BR specification no. 931A and it is used as external relays
- QBA1 Relay is DC biased with AC immune neutral line relay, a copper slug is provided for immunization and a permanent magnet biases the core
- Will not operate if 20 times the rated voltage is applied in reverse and specification is BR Specification No. 932 A
- QBCA1, similar to QBA1, has two heavy-duty front contacts capable of carrying 30A inductive current at 110 V and the back contact can carry 3A continuous and 2A switching current
- Its Specification is BR specification no 943 and is used as Point contactor relays
- QSPA1 is used as a repeater for 'Q' series track relays due to its slow pickup, copper slug between the core and the heelpiece, and a magnetic shunt
- Has a slow pickup by 540/600 milliseconds, releases less slowly by 140/200 milliseconds, and is immune to AC and specification is BR No. 933A
- QL1 is magnetically latched DC line relay that remains fully operated without continuous feed, has two coils (operate and release) and a permanent magnet and specification is BR No. 935A
- Are used as latch relays in block instruments
Track Relays
- Should be metal to carbon contact type and plug-in type unless specifically permitted
- In non-electrified areas, 9-ohm DC non-AC immunized relays are used
- In electrified areas, 9 ohm DC neutral, AC immunized, 9-ohm DC-biased, AC immunized relays are used
- Double element motor type relays operating on 83 1/3 Hz in AC traction areas and 50 Hz in DC traction areas can be used
- Vane type relays may be used until replacement. Relays for coded, pulsed, electronic (audio or high frequency) track circuits are of an approved track/line relay type
- Construction is similar to a Q-series line relay but with reduced contact load and are more sensitive, and workable on a low voltage.
QT2 Relay
- Has one core and 2F-1B contacts, the back contact provides cross protection for TPR circuits and a single coil unlike shelf types, which has two coils with open ends
- Is used as track relay in Non-RE areas
- QTA2 Relay has a Copper slug on the core for AC immunity, pick-up voltage is 1.4 V and pick-up current is about 140mA
- Available in 9 Ohms coil resistance with 2F/1B contact configuration which requires more DC operating power and takes longer to pick and drop due to copper slug
- New installations can use up to 450-meter track circuit lengths in RE Areas with choke at both ends
- Existing installations: up to 450 meters with choke at the relay end with 1000 Amps traction return and up to 350 meters without choke with 600 amps traction return
- Used as track relay in RE areas
- QBAT Relay has a pick-up voltage of 1.75 V and pick-up current of ~175 mA and achieved with biasing permanent magnet on its core with its copper slug and one core and 2F-2B contacts
- For use up to 750 meters track circuit lengths with choke in RE Areas and conformance with RDSO specification No. 84/88 and used as a track relay in RE areas.
Timer Relays
- Used in signaling circuits to release interlocking after a set time
- DC Thermal, Siemens Motorised Clock Work, Motor and Electronic
- Employs heat-operated contact with a DC Neutral Relay, with a heating element (H) and a neutral line relay (R) energizing an external line relay after a time delay
- "QJ1" type relays are feature rated voltage of 24 V DC or 50 V DC, a heat coil resistance of 40-42 Ohms, maximum Heating power 15 Watt at rated supply voltage.
- Operations restricted to 100/day or heating element changes, a 10% voltage increase may decrease time by 10% and a similar voltage decrease may decrease time by 20%.
- Used for timing in Signalling.
Electronic Timer Relays
- Used to achieve time delay by charge, discharge, clock pulse or integrated circuits
- Used to time delay
- Available only in group units of different sizes which includes Mini, Minor and Major groups
- Mini Group: 2 Neutral relays, 2 Interlocked relay or ECR with power conversion unit.
- Minor Group: 15 Neutral with variations in neutral and contactor relays or resistors.
- Major Group: Up to 30 relays with combinations of neutral/interlocked relays and space variations
Group relays in Siemens interlocking
- 2-Aspect Signal, 3-Aspect Signal, Shunt Signal, Universal Route, Point for PI/RRI and Point Chain
- Available in 4F/4B, 5F/3B & 6F/2B contact configurations.
- Ohmic values are 1260 ohms for 4F/4B/5F/3B and 1840 ohms for 6F/2B
- Available in 4F/4B, 5F/3B & 6F/2B contact configurations with ohmic values of 615 ohms
AC immunized relays
- Are available in 5F/3B and the top relay is1840 ohms and bottom relay is 1260 ohms
- Used as Z1WR1, Z1NWR, Z1RWR, WKR3, Z1WR, WLR in point control circuits
- Available in 5F/3B contact configuration only in which, the top relay is 1340 ohms and bottom relay is 1590 ohms
Universal ECR
- Relays are available in 3F/3B contact configuration only with with an ohmic value of 83.1 ohms
- It is used as lamp proving relay. WKR1s/WKR2s are available in 5F/3B configuration with an ohmic value of 1840 ohms and is used for point detection
- WJRs are available in 2F/2B contact configurations with an 1840 ohms ohmic value
- It gives 10 sec time duration for point operation.
WR Heavy Duty Relay
- Is available in 2F/2B contact configurations with an ohmic value of 60 ohms
- All are a part of Point minor group and Point Major and point motor operation
- Operates on 11 OV +/- 10% AC, timing from 1 to 5 minutes
- Resets automatically, a synchronous motor drives and switches contacts after the time lapse
- If prematurely interrupted, mechanism goes back to normal before actuating contacts and used for time delay
ECR Relays
- Relays must be of an approved type.
- Plug-in line relays of Neutral/Polar Biased/Magnetic latch/Interlocked type rated at 24/48/60 V DC
- Suitable LED lamp relays (QECX-61) meet signal parameters and suit lamps
- Universal Plug-in, Tractive armature AC lamp relays are metal to carbon types and is as per RDSO specification STS/E/Relays/AC Lit LED Signal/09-2002 (Amdt1) & BRS- 941A and used for 110V AC LED lamps
- Important parameters include ECR pickup at 108 mA/AC, 50Hz, drop away at 72 mA/AC, 50Hz, withstands for continuous current of 250 mA/AC 50Hz Contact configuration: 4F-4B identically in A to D rows
- Voltage drop across R1/R2 is less than 10V @ 125 mA/AC.
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