1 Answer

Answer :

A differential relay measures the vector difference between two or more similar electrical quantities.

Related questions

Description : What is the difference between relay and contactor?

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

Description : What is the difference between a switch and a relay?

Last Answer : Switch is simply a mechanical contact mechanism and relay is a electromagnetic switch . Switch can be direct mechanically turn on and off but relay can be operated by energising coil .

Description : 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

Description : State the difference between energy conservation and energy audit. 

Last Answer : energy conservation Energy audit It is reducing the growth of energy consumption by avoiding unnecessary usage of energy It is an inspection, survey & analysis of energy flows ... Various measuring instruments, with proper sensing elements are required for the energy audit. 

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Last Answer : Direct current is the flow of electricity or charge in one direction..  Alternative current is the flow of charge that doesn't flow in one direction. 

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Last Answer : Open circuit means the wire is cut meaning power will not flow and close circuit means wire is not cut and hence power will flow.Short circuit is the same as close circuit

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Last Answer : Absolute Instrument Secondary Instrument 1. These give magnitude of quantity in terms physical constants of instruments 1. These give reading directly of the quantity at the time of ... Raleigh current balance. 6. Examples - ammeter, voltmeter, amperehour meter, wattmeter etc.

Last Answer : In a single phase power factor meter the phase difference between the currents in the two pressure coils is exactly 90°.

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Description : What is the difference between an AC and DC generator?

Last Answer : The generator which generates DC voltage is called DC generator and generator which generates AC voltage is called AC generator (or) Alternator. In DC generator armature is rotated and field winding ... generator. A DC generator can generate low voltages but an AC generator can generate upto 11kv.

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Last Answer : Loss occurred by magnetising and demagnetising process is called histerisis loss and the current flowed due to the magnetic field produced by the electric field applied is called eddy current losses

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Last Answer : The anode is positively charged electrode and the cathode is negatively charged electrode.

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Last Answer : Dielectric is the another name for insulator.

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Last Answer : AC means alternating current It's Frequency is 50hz Dc means direct current ItsI Frequency is 0Hz

Description : What is the difference between line and phase current?

Last Answer : The currents flows through phase lines is called line voltage and currents flows from phase to neutral line is called phase current

Description : What is the difference between line and phase voltage?

Last Answer : Line voltage  is  voltage  between two  phases R &Y  (415 v)  while  phase  voltage  is  the  voltage  between  one  phase and  a neutral  B &  N   (240 v).

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Description : Distinguish between AC and DC.

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Description : what is the difference between AC and DC current ?

Last Answer : AC is generated using Alternator. DC is generated using DC generator. AC changes its direction periodically. DC do not change its direction periodically. AC have non zero frequency. DC have zero ... Power factor of AC is between 0 and 1. But power factor of DC is always 1.

Description : What the difference between vector and scalar quantities is?

Last Answer : A vector has both strength and direction, a scalar quantity can be described using only 1 quantity, magnitude. Example of vector quantities are velocity, acceleration etc. Examples of scalar quantities are time, energy and volume since they only represent magnitude and no direction.

Description : Explain space diagram & vector diagram

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Description : A differential amplifier has a differential gain of 28000 and CMRR is 60 dB. What will be the value of common mode gain? A) Ac = 0.125 B) Ac = 0.33 C) Ac = 3 D) Ac = 28 

Last Answer : A differential amplifier has a differential gain of 28000 and CMRR is 60 dB. What will be the value of common mode gain? A) Ac = 0.125 B) Ac = 0.33 C) Ac = 3 D) Ac = 28 

Description : A differential amplifier has a differential gain of 20,000, CMRR : 80 dB. The common mode gain is given by

Last Answer : A differential amplifier has a differential gain of 20,000, CMRR : 80 dB. The common mode gain is given by 2

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Last Answer : kWh meter is the electric meter that measures the amount of electrical Energy in kWh that was consumed in the house. 

Last Answer : Meggar is an instrument which measures the insulation resistance of an electric circuit relative to earth and one another.

Description : 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 : D

Description : 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

Description : The operating time of instantaneous relay is

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

Description : 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 

Description : 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 

Description : 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 

Description : Reactance relay is normally preferred for protection against

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

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

Description : 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

Last Answer : The torque produced in induction type relay (shaded pole structure) is inversely proportional to the square of the current.

Last Answer : Admittance relay is directional relay.

Last Answer : The relay with inverse time characteristic will operate within 5 to 10 sec.

Last Answer : The under voltage relay can be used for generators, busbars, transformers, motors.

Last Answer : Reactance relay is preferred for phase fault on short transmission line.

Last Answer : Induction cup relay is operated due to changes in current, voltage, impedance.

Last Answer : Interruption of large currents by relay requires arc suppressing blow out coils, wide separation of the opened contacts, high speed opening of contacts.

Last Answer : Overheating of relay contacts or contact born out is due to slow making and breaking of load circuit contacts, foreign matter on the contact surface, too low contact pressure.