Recent questions tagged relay

asked Aug 28, 2019 by anonymous

main parts of Relay

Last answer: Coil, plunger, contacts, springs, connecting terminals and enclosure.

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asked Aug 12, 2019 by anonymous

What is phase failure relay and how it's work?

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asked May 8, 2018 by anonymous

The purpose of the restraining coil in a biased differential relay is

The purpose of the restraining coil in a biased differential relay is (A) To reduce CT saturation during fault. (B) To increase the sensitivity of the relay. (C) To match the transformation ratio. (D) To limit the spill current through the relay during heavy external fault.

Last answer: d

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532 views 2 answers

asked May 8, 2018 by anonymous

A relay used for protection of motors against overload is :

A relay used for protection of motors against overload is : (A) Impedance relay (B) Electromagnetic attraction type (C) Thermal relay (D) Buchholz's relay

Last answer: A relay used for protection of motors against overload is : Thermal relay

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242 views 1 answer

asked May 3, 2018 by anonymous

A relay has a rating of 5 A, 2.2 sec IDMT and a relay setting of 125% TMS = 0.6. It is connected to a supply

A relay has a rating of 5 A, 2.2 sec IDMT and a relay setting of 125% TMS = 0.6. It is connected to a supply circuit through a C.T. 400/5 ratio. The fault current is 4000 A. The operating current of the relay is

Last answer: A relay has a rating of 5 A, 2.2 sec IDMT and a relay setting of 125% TMS = 0.6. It is connected to a supply circuit through a C.T. 400/5 ratio. The fault current is 4000 A. The operating current of the relay is 6.25A

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424 views 1 answer

asked May 3, 2018 by anonymous

The operating time of instantaneous relay is

Last answer: The operating time of instantaneous relay is 0.1 sec

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asked May 2, 2018 by anonymous

What is the difference between relay and contactor?

Last answer: Relay have smaller ratings. Contactor is a high rating relay.

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5.0k views 1 answer

asked May 1, 2018 by anonymous

A negative sequence relay is used for protection of

A negative sequence relay is used for protection of (1) Generator (3) Motor (2) Transformer (4) Long Transmission lines

Last answer: A negative sequence relay is used for protection of Generator

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454 views 1 answer

asked Apr 30, 2018 by anonymous

Buchholz relay is

Buchholz relay is (1) located in the conservator tank (2) located in the transformer tank itself (3) connected in the pipe connecting main tank of transformer and conservator (4) installed in the circuit breaker

Last answer: Buchholz relay is connected in the pipe connecting main tank of transformer and conservator

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58 views 1 answer

asked Apr 29, 2018 by anonymous

To prevent mal-operation of differentially connected relay while energizing a transformer, the relay

To prevent mal-operation of differentially connected relay while energizing a transformer, the relay restraining coil is based with (1) second harmonic current (2) third harmonic current (3) fifth harmonic current (4) seventh harmonic current

Last answer: To prevent mal-operation of differentially connected relay while energizing a transformer, the relay restraining coil is based with second harmonic current

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252 views 1 answer

asked Apr 29, 2018 by anonymous

Reactance relay is normally preferred for protection against

Last answer: Reactance relay is normally preferred for protection against earth faults

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72 views 1 answer

asked Apr 29, 2018 by anonymous

Buchholz relay is used as a safety device with respect to which of the following?

Buchholz relay is used as a safety device with respect to which of the following? A) Audio transformers B) Oil filled power transformers C) Air core transformer D) None of these

Last answer: Buchholz relay is used as a safety device with respect to which of the following? A) Audio transformers B) Oil filled power transformers C) Air core transformer D) None of these

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75 views 1 answer

asked Apr 28, 2018 by anonymous

In the induction type directional over current relay, when a short-circuit occurs in the circuit

In the induction type directional over current relay, when a short-circuit occurs in the circuit (A) power flows in reverse direction (B) power flows in normal direction (C) directional power element does not operate (D) over current element is not energized

Last answer: In the induction type directional over current relay, when a short-circuit occurs in the circuit power flows in reverse direction

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77 views 1 answer

asked Apr 28, 2018 by anonymous

A solid state relay

A solid state relay (A) withstands voltage transients (B) does not require auxiliary dc supply (C) provide low burden on CT and P (D) does not provide earth fault protection

Last answer: A solid state relay provide low burden on CT and P

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asked Apr 28, 2018 by anonymous

A reactance relay is

A reactance relay is (A) Voltage restrained directional relay (B) Directional restrained over-current relay (C) Voltage restrained over current relay (D) Directional restrained over voltage relay

Last answer: A reactance relay is Directional restrained over-current relay

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78 views 1 answer