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Answer :

Burden of a protective relay is the power absorbed by the circuit of relay.

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Description : The operating point of a protective current transformer is near the

Last Answer : The operating point of a protective current transformer is near the Ankle point

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.

Last Answer : An efficient and a well designed protective relaying should have good selectivity and reliability, economy and simplicity, high speed and selectivity.

Description : what is reverse power relay?

Last Answer : Thereverse powerrelay is a directional protective relay that prevents power from flowing in the reverse direction. Read our article going back ... it all to be up to date. And if you do, read it anyway just to check if youreallydo!

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 : 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 : What is the difference between relay and contactor?

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

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.

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

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.

Last Answer : The relay operating speed depends upon the spring tension, the rate of flux built up, armature core air gap.

Description : How do relay works ?

Last Answer : Relay working like contact it is noise less 

Description : What is the use of Buchholz relay in transformer?

Last Answer : This is a transformer that is used to step up and down current. 

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 : Fuel Pump Relay

Last Answer : Some car owners immediately suspect a fuel pump failure when their cars stall. However, there are many other engine problems that may resemble a fuel pump failure, such as restricted fuel filters, smashed ... advisable to bring your car to the repair shop so that the whole engine can be checked.

Description : main parts of Relay

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

Description : 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

Description : 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

Last Answer : A Buchholz relay can be installed on oil cooled transformers.

Last Answer : Buchholz's relay gives warning and protection against electrical fault inside the transformer itself.

Description : Burden of a protective relay is the power (a) required to operate the circuit breaker (b) absorbed by the circuit of relay (c) developed by the relay circuit (d) none of the above

Last Answer : (b) absorbed by the circuit of relay

Description : The burden of protective Current Transformer (CT) is specified in

Last Answer : The burden of protective Current Transformer (CT) is specified in Volt - Ampere

Description : When the truth becomes not "power", as the saying goes, but a burden, what do you do?

Last Answer : You denounce it as “fake news”.

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. 

Description : The main disadvantages of having poor power factors are:  (A) High cost of station and distribution equipment (B) Poor voltage regulation (C) High energy loss in conductor (D) All of the above

Last Answer : The main disadvantages of having poor power factors are:  (A) High cost of station and distribution equipment (B) Poor voltage regulation (C) High energy loss in conductor (D) All of the above

Description : A lightening arrester connected between the line and earth in a power system  (1) protects the terminal equipment against travelling surges (2) protects the transmission line against direct ... suppresses high frequency oscillations in the line (4) reflects back the travelling wave approaching it

Last Answer : A lightening arrester connected between the line and earth in a power system protects the terminal equipment against travelling surges

Description : The reactive power transfer over a line mainly depends on

Last Answer : The reactive power transfer over a line mainly depends on lVsl- lVRl

Description : For a 15-bus power system with 3 voltage controlled buses, the size of Jacobian matrix is

Last Answer : For a 15-bus power system with 3 voltage controlled buses, the size of Jacobian matrix is 25 x 25

Description : With fault clearing time, the transient stability of a power system

Last Answer : With fault clearing time, the transient stability of a power system decreases

Description : To protect the power transformer (Y-Y with neutral grounded) against fault, what type of connection do the CTs have ?

Last Answer : To protect the power transformer (Y-Y with neutral grounded) against fault, what type of connection do the CTs have ? Δ-Δ connection

Description : Regulating-transformers are used in power systems for control of

Last Answer : Regulating-transformers are used in power systems for control of power flow

Last Answer : The power loss is an important factor for the design of transmission line.

Last Answer : The inductive interference between power and communication line can be minimized by transposition of the power line, transposition of the communication line.

Last Answer : The steady state stability of the power system can be increased by connecting lines in parallel.

Last Answer : Air blast circuit breakers for 400 kV power system are designed to operate in 50 millisecond.