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Answer :

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

Related questions

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

Description : The operating time of instantaneous relay is

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

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

Last Answer : Circuit breakers usually operate under transient state of short-circuit current.

Description : 3X3 inverse of matrix short trick

Last Answer : 3X3 inverse of matrix short trick

Description : What is the inverse of reactance?

Last Answer : Inverse of reactance is Susceptance .Unit of Susceptance is Siemens.

Last Answer : For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.

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

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 : Draw and explain the characteristic of UJT. 

Last Answer : UJT Characteristics: The UJT characteristic is emitter voltage versus emitter current characteristic, as shown in the figure. There three operating regions in UJT  1.Cut off region: For ... in IE will place the device into saturation and hence after valley point there is valley point. 

Description : The unit heat rate characteristic of a thermal power unit shows :  (A) Heat input per kWh of output versus the megawatt output of unit  (B) Heat input per kW of output versus the megawatt output ... hour output of unit  (D) Heat input per kW of output versus the megawatt hour output of unit

Last Answer : The unit heat rate characteristic of a thermal power unit shows : Heat input per kWh of output versus the megawatt output of unit 

Description : Which of the following statements is not characteristic of a static magnetic field? (A) It is solenoidal. (B) It is conservative. (C) It has no sinks or sources. (D) Flux lines are always closed.

Last Answer : Which of the following statements is not characteristic of a static magnetic field? (A) It is solenoidal. (B) It is conservative. (C) It has no sinks or sources. (D) Flux lines are always closed.

Description : Which diode exhibits negative resistance characteristic? (A) LED (B) Zener (C) Tunnel diode (D) PN diode

Last Answer : Which diode exhibits negative resistance characteristic? (A) LED (B) Zener (C) Tunnel diode (D) PN diode

Last Answer : Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. compound motor.

Description : The relay with inverse time characteristic will operate within (a) 1.5 sec (b) 5 to 10 sec (c) 5 to 20 sec (d) 20 to 30 sec (e) none of the above

Last Answer : (b) 5 to 10 sec

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 : 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 : If a relay fails to operate for a fault within its reach, it is said to

Last Answer : If a relay fails to operate for a fault within its reach, it is said to Under reach

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 : ln HRC fuse the time between cut-off and final current zero is called

Last Answer : ln HRC fuse the time between cut-off and final current zero is called the arcing time

Last Answer : The time of closing the cycle, in modern circuit breakers is 0.003 sec.

Description : What is the characteristic of inverse time over current relay?  

Last Answer : If the fault current increases the time of the operation of the relay will be decreases.  

Description : Draw a typical time-current characteristic for IDMT relay. 

Last Answer : Time-Current Characteristic for IDMT Relay: