Directional relays are based on flow of?

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Answer :

Directional relays are based on flow of power.

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Related questions

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

Description : 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

IDMT relays are used to protect the transformer against :

Description : IDMT relays are used to protect the transformer against :  (A) Internal short -circuits (B) Open circuits (C) External short circuits (D) Oil leakage

Last Answer : IDMT relays are used to protect the transformer against : External short circuits

The inverse definite mean time relays are used for over current and earth fault protection of transformer against?

Last Answer : The inverse definite mean time relays are used for over current and earth fault protection of transformer against internal short-circuits.

The single phasing relays are used for the protection of?

Last Answer : The single phasing relays are used for the protection of three phase motors.

Which relays are used for phase faults on long line?

Last Answer : Impedance relays are used for phase faults on long line.

Discrimination between main and backup protection is provided by the use of relays which are?

Last Answer : Discrimination between main and back up protection is provided by the use of relays which are slow.

To protect most of the electrical equipment handling low power, the types of relays used are?

Last Answer : To protect most of the electrical equipment handling low power, the types of relays used are thermocouple, electronic and bimetallic.

Protective relays are devices that detect abnormal conditions in electrical circuits by measuring?

Last Answer : Protective relays are devices that detect abnormal conditions in electrical circuits by measuring constantly the electrical quantities which differ during normal and abnormal conditions.

D.C. shunt relays are made of?

Description : D.C. shunt relays are made of?

Last Answer : D.C. shunt relays are made of many turns of thin wire.

Thermal overload relays are used to protect the motor against over current due to?

Last Answer : Thermal overload relays are used to protect the motor against overcurrent due to heavy loads.

Overload relays are of?

Last Answer : Overload relays are of induction, solid state, thermal, electromagnetic type.

Relays can be designed to respond to changes in?

Last Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.

Consider the following statements. Which of these statements are correct ? (1) Reactance relays are preferred

Description : Consider the following statements. Which of these statements are correct ?  (1) Reactance relays are preferred for ground fault relaying  (2) Impedance relays are most suitable for:protecting long transmission lines  (3) Mho relays are best ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)

Last Answer : Consider the following statements. Which of these statements are correct ?  (1) Reactance relays are preferred for ground fault relaying  (2) Impedance relays are most suitable for:protecting long transmission lines  (3) Mho relays are ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)

Directional relays are based on flow of (a) power (b) current (c) voltage wave (d) all of the above

Description : Directional relays are based on flow of (a) power (b) current (c) voltage wave (d) all of the above

Last Answer : (a) power

Mention some of the applications of Directional Over-Current relays?

Description : Mention some of the applications of Directional Over-Current relays?

Last Answer : 1. Double end fed power system 2. Single end fed system of parallel feeders 3. Ring main feeder system

Define the following terms with respect to protective relays i) Relay time ii) Reset current iii) Plug setting multiplier and iv) Time setting multiplier

Description : Define the following terms with respect to protective relays i) Relay time ii) Reset current iii) Plug setting multiplier and iv) Time setting multiplier

Last Answer : 1) Relay Time: The time interval between occurrence of fault and closure of relay contacts.  2) Reset Current: The value of current below which the relay resets and comes back to ... The adjustment arrangement provided for setting the operation time of relay is known as Time setting multiplier. 

For the protection of parallel feeders fed from one end, the relays used are:

Description :  For the protection of parallel feeders fed from one end, the relays used are: A) non-directional relays at the source-end and directional relays at the load-end B) non-directional relays at both the ... at the source-end and non-directional at the load-end D) directional relays at both the ends

Last Answer : For the protection of parallel feeders fed from one end, the relays used are: non-directional relays at the source-end and directional relays at the load-end

Electrical contact materials used in switches, brushes and relays must possess

Description : Electrical contact materials used in switches, brushes and relays must possess   (A) high thermal conductivity and high melting point  (B) Low thermal conductivity and low melting point   (C) High thermal conductivity and low melting point  (D) Low thermal conductivity and high melting point.

Last Answer : Electrical contact materials used in switches, brushes and relays must possess high thermal conductivity and high melting point 

Reactance relays are employed for Phase faults in :

Description : Reactance relays are employed for Phase faults in : (A) Short lines (B) Medium lines (C) Long lines (D) Any line

Last Answer : Reactance relays are employed for Phase faults in : Short lines

Explain construction and operation of induction type directional over current relay.

Description : Explain construction and operation of induction type directional over current relay.

Last Answer : Directional overcurrent relay: Construction: It consists of two units: i) Non-directional Over-current unit ii) Directional power unit The directional unit consists of upper electromagnet ... closes the trip circuit. This operates circuit breaker which isolates the faulty section. 

30°, 60° and 90° connections are made in a directional relay to render the relay

Description : 30°, 60° and 90° connections are made in a directional relay to render the relay (A) Sufficient torque under fault conditions (B) Zero torque under fault conditions (C) Current grading (D) Time grading

Last Answer : 30°, 60° and 90° connections are made in a directional relay to render the relay Sufficient torque under fault conditions

Why bi-directional flow is chosen for PHT system?

Description : Why bi-directional flow is chosen for PHT system?

Last Answer : Bi-directional flow is chosen for PHT system because, a. Uniform temperature gradient is facilitated so there will be no differential thermal expansion. b. It facilitates fuelling even when the ... , which facilitates uniform neutron flux and this intern gives rise to maximum fuel burns up. 

In order that current should flow without causing excessive heating or voltage drop, the relay contacts should?

Last Answer : In order that current should flow without causing excessive heating or voltage drop, the relay contacts should have low contact resistance, be clean and smooth, be of sufficient size and proper shape.

Explain operation of µP based relay with block diagram

Description : Explain operation of µP based relay with block diagram

Last Answer : Operation of Microprocessor (µP) based relay: The inputs from the power system through CTs and PTS are received by the analog Input receiver; they are sampled simultaneously or ... compares the dynamic inputs and decides accordingly to generate trip/alarm signal to the output device.

Neural system which relays impulses from CNS to skeletal muscles is

Description : Neural system which relays impulses from CNS to skeletal muscles is

Last Answer : Neural system which relays impulses from CNS to skeletal muscles is

Neural system which relays impulses from CNS to skeletal muscles is

Description : Neural system which relays impulses from CNS to skeletal muscles is

Last Answer : Neural system which relays impulses from CNS to skeletal muscles is

Where are the Air con relays?

Description : Where are the Air con relays?

Last Answer : Need answer

Do relays use high voltage to control low currant circuits?

Description : Do relays use high voltage to control low currant circuits?

Last Answer : Low voltage to operate relay controlling high CURRENT circuits(currant is a dried fruit).

Do relays use high voltage to control low currant circuits?

Description : Do relays use high voltage to control low currant circuits?

Last Answer : Low voltage to operate relay controlling high CURRENT circuits(currant is a dried fruit).

Who built the world’s first electronic calculator using telephone relays, light bulbs and batteries? A) Claude Shannon B) Konrard Zues C) George Stibits D) Howard H. Aiken

Description : Who built the world’s first electronic calculator using telephone relays, light bulbs and batteries? A) Claude Shannon B) Konrard Zues C) George Stibits D) Howard H. Aiken

Last Answer : Answer : C

The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Description : The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Last Answer : Ans: A

If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of wood C. inject small amounts of CO2 into the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents

Description : If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of ... the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents

Last Answer : Answer: A

When the master switch for the winch shown in the illustration is in the 'off' position, and the line & safe switches are closed, which of the listed relays should be energized? EL-0102 A. 'DB' & '2T' B. 'DB' & '4M' C. 'FR-B.O.' & 'LV' D. '1M' & '1A'

Description : When the master switch for the winch shown in the illustration is in the 'off' position, and the line & safe switches are closed, which of the listed relays should be energized? EL-0102 A. 'DB' & '2T' B. 'DB' & '4M' C. 'FR-B.O.' & 'LV' D. '1M' & '1A'

Last Answer : Answer: C

Motor controllers are seldom troubled by grounds because ________________. A. cabinet heaters always keep internal components dry B. special insulation is used on wire for vital circuits C. shock mounts on controller panels greatly reduce vibration D. contactors and relays are mounted on nonconducting panels

Description : Motor controllers are seldom troubled by grounds because ________________. A. cabinet heaters always keep internal components dry B. special insulation is used on wire for vital circuits C. ... on controller panels greatly reduce vibration D. contactors and relays are mounted on nonconducting panels

Last Answer : Answer: D

A faulty 'function generator' shown in the illustration may prevent _____________. EL-0095 A. proper pitch control from both the 'bridge' and 'engine room thrust levers' B. the 'split potentiometer's' ability to control pitch C. the pitch meter from indicating accurately D. relays #2 and/or #3 from energizing

Description : A faulty 'function generator' shown in the illustration may prevent _____________. EL-0095 A. proper pitch control from both the 'bridge' and 'engine room thrust levers' B. the 'split potentiometer ... control pitch C. the pitch meter from indicating accurately D. relays #2 and/or #3 from energizing

Last Answer : Answer: A

When power is restored after a complete power failure, a steering gear pump motor will ____________. A. have to be restarted B. have to be reset C. restart automatically D. trip its overload relays

Description : When power is restored after a complete power failure, a steering gear pump motor will ____________. A. have to be restarted B. have to be reset C. restart automatically D. trip its overload relays

Last Answer : Answer: C

Power necessary to operate the horn relay shown in the illustration ____________. EL-0093 A. comes from each station's magneto B. is supplied from a 115 volt source C. is conducted through the relay's contacts D. also lights lamps 'R' and 'T'

Description : Power necessary to operate the horn relay shown in the illustration ____________. EL-0093 A. comes from each station's magneto B. is supplied from a 115 volt source C. is conducted through the relay's contacts D. also lights lamps 'R' and 'T'

Last Answer : Answer: A

As shown in the illustration, when the 'speed control' system is in 'SPLIT' _______________. EL-0096 A. Relays #1, #5 and #8 are not used B. the 'slew rated controller' is grounded through Relay #6 C. the RPM 'function generator' and 'thrust levers' have no control D. the 'E/P converters' are bypassed and air is fed directly to the governors via the 'load sharing valve'

Description : As shown in the illustration, when the 'speed control' system is in 'SPLIT' _______________. EL-0096 A. Relays #1, #5 and #8 are not used B. the 'slew rated controller' is grounded through Relay ... E/P converters' are bypassed and air is fed directly to the governors via the 'load sharing valve'

Last Answer : Answer: C

The division of the kilowatt load between two AC generators operating in parallel is controlled by the settings and characteristics of the _____________. A. voltage regulators B. field rheostats C. reverse power relays D. prime mover governors

Description : The division of the kilowatt load between two AC generators operating in parallel is controlled by the settings and characteristics of the _____________. A. voltage regulators B. field rheostats C. reverse power relays D. prime mover governors

Last Answer : Answer: D

Line losses in a distribution circuit are kept to a minimum by __________. A. adding rubber insulation conductors to the circuit B. using higher current and lower voltage C. increasing the number of thermal relays in the circuit D. using higher voltage and lower current

Description : Line losses in a distribution circuit are kept to a minimum by __________. A. adding rubber insulation conductors to the circuit B. using higher current and lower voltage C. increasing the number of thermal relays in the circuit D. using higher voltage and lower current

Last Answer : Answer: D

On an engine throttle control system, the auxiliary control circuits are provided with devices to prevent excessive overtravel of the pilot valve by the synchronous motor. These devices are called _________________. A. overlap sensors B. limit switches C. overtravel relays D. proximity switches

Description : On an engine throttle control system, the auxiliary control circuits are provided with devices to prevent excessive overtravel of the pilot valve by the synchronous motor. These devices are called _________________. A. overlap sensors B. limit switches C. overtravel relays D. proximity switches

Last Answer : Answer: B

Motor controllers are seldom troubled with grounds because _____________. A. the auxiliary contacts have a high resistance connection B. the contactors and relays are mounted on a nonconducting panel C. the resistor banks are composed of individual series-connected units D. there are separate switches for the motor and the control

Description : Motor controllers are seldom troubled with grounds because _____________. A. the auxiliary contacts have a high resistance connection B. the contactors and relays are mounted on a nonconducting panel ... individual series-connected units D. there are separate switches for the motor and the control

Last Answer : Answer: B

The alarm system for an engine order telegraph uses small selsyn motors attached to the indicators. The alarm sounds when the rotors are _____________. A. in synchronous position, no current is flowing, and the relays are open B. in synchronous position, no current is flowing, and the relays are closed C. not synchronized, current is flowing, and the relays are open D. not synchronized, current is flowing, and the relays are closed

Description : The alarm system for an engine order telegraph uses small selsyn motors attached to the indicators. The alarm sounds when the rotors are _____________. A. in synchronous position, no current is flowing, ... and the relays are open D. not synchronized, current is flowing, and the relays are closed

Last Answer : Answer: D

Which of the following statements represents the main difference between a relay and a contactor? A. Contactors control current and relays control voltage. B. A relay is series connected and a contactor is parallel connected. C. Contactors can handle heavier loads than relays. D. Contactors are made from silver and relays are made from copper.

Description : Which of the following statements represents the main difference between a relay and a contactor? A. Contactors control current and relays control voltage. B. A relay is series connected and a contactor ... loads than relays. D. Contactors are made from silver and relays are made from copper.

Last Answer : Answer: C

What are different types of principles of operation of electro-mechanical relays?

Description : What are different types of principles of operation of electro-mechanical relays?

Last Answer : Answer: Electro-mechanical relays operate by two principles. Electro-magnetic attraction and electromagnetic induction. In electromagnetic attraction relay plunger is drawn to the solenoid or an ... operation is similar to induction motor. Torque is developed by electromagnetic induction principle

How relays are connected in the power system?

Description : How relays are connected in the power system?

Last Answer : Answer: The relays are connected to the power system through the current transformer (CT) or potential transformer (PT).

What are the different relays that employed for protection of apparatus and transmission lines?

Description : What are the different relays that employed for protection of apparatus and transmission lines?

Last Answer : Answer: The relays that are usually employed for protection of transmission lines include • Over current relay • Directional relay • Distance relay • Under Voltage relay • Under-frequency relay • Thermal relay • Differential relay • Phase sequence relays • pilot relays

Mention any 2 applications of differential relays.

Description : Mention any 2 applications of differential relays.

Last Answer : Protection of generator and generator-transformer unit: protection of large motors and bus bars

What are over and under current relays?

Description : What are over and under current relays?

Last Answer : Overcurrent relays are those that operate when the current in a line exceeds a predetermined value. (eg: Induction type non-directional/directional overcurrent relay, differential overcurrent relay)whereas ... in a circuit/line drops below a predetermined value.(eg: differential over-voltage relay)