Please Log in or Register for more.


95 views

1 Answer

Answer :

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

Like 0 like

Please log in or register to answer this question.

Related Questions


What is voltage interruption?

Show More

51 views 0 answers







Explain following techniques related to energy conservation in transmission and distribution system. (i) By balancing phase currents (ii) Variable technical losses (I2R losses).
Last Answer : (i) Balancing Phase currents: Proper (healthy balanced) three phase loads always draw equal currents in all lines but single phase loads in the 3 phase 4 wire system or loads connected between two ... . 11) Minimize I2R losses. 12) Balance the load currents. 13) Regulate the system voltages.

Show More

196 views 1 answer







The transient currents are associated with the?
Last Answer : The transient currents are associated with the changes in the stored energy in the inductors and capacitors.

Show More

71 views 1 answer








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

Show More

352 views 1 answer








Last Answer : For handling greater currents induction wattmeters are used in conjunction with current transformers.

Show More

139 views 1 answer







Eddy currents are induced in the pole shoes of a D.C. machine due to?
Last Answer : Eddy currents are induced in the pole shoes of a D.C. machine due to relative rotation between field and armature.

Show More

231 views 1 answer







How eddy currents are generated?

Show More

69 views 0 answers







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

Show More

710 views 2 answers







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

Show More

548 views 2 answers







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

Show More

728 views 1 answer







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

Show More

117 views 1 answer







What is the difference between relay and contactor?
Last Answer : Relay have smaller ratings. Contactor is a high rating relay.

Show More

5.1k views 1 answer







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 

Show More

627 views 1 answer







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 

Show More

117 views 1 answer







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 

Show More

496 views 1 answer







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

Show More

120 views 1 answer







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

Show More

123 views 1 answer







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

Show More

68 views 1 answer








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

Show More

829 views 1 answer








Last Answer : Admittance relay is directional relay.

Show More

154 views 1 answer








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

Show More

115 views 1 answer








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

Show More

68 views 1 answer








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

Show More

110 views 1 answer








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

Show More

352 views 1 answer








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.

Show More

150 views 1 answer








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

Show More

159 views 1 answer








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

Show More

810 views 1 answer








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.

Show More

153 views 1 answer








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

Show More

271 views 1 answer







How do relay works ?
Last Answer : Relay working like contact it is noise less 

Show More

134 views 1 answer







What is the use of Buchholz relay in transformer?
Last Answer : This is a transformer that is used to step up and down current. 

Show More

152 views 1 answer







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 .

Show More

110 views 1 answer







Interruption of large currents by relay requires (a) arc suppressing blow out coils (b) wide separation of the opened contacts (c) high speed opening of contacts (d) all of the above
Last Answer : (d) all of the above

Show More

13 views 1 answer







How to Shrink Large Pores
Last Answer : How to Shrink Large Pores Large pores can be a hassle, especially in a world full of airbrushed models with no visible pores filling our magazine pages. Large pores can also lead to a tendency ... add calamine or sandalwood powder to the tomato juice before applying. Rinse it off with warm water.

Show More

4 views 1 answer







A large AC generator, supplying power to an infinite bus, has a sudden short-circuit occurring at its terminals. Assuming the prime mover input and the voltage behind the transient reactance to remain constant immediately after the fault, acceleration of the generator rotor is
Last Answer : A large AC generator, supplying power to an infinite bus, has a sudden short-circuit occurring at its terminals. Assuming the prime mover input and the voltage behind the transient reactance ... , acceleration of the generator rotor is inversely proportional to the moment of inertia of the machine

Show More

142 views 1 answer








Last Answer : A sensitive galvanometer produces large deflection for a small value of current.

Show More

234 views 1 answer








Last Answer : Large capacity generators are invariably hydrogen cooled.

Show More

95 views 1 answer







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.

Show More

10 views 1 answer







main parts of Relay
Last Answer : Coil, plunger, contacts, springs, connecting terminals and enclosure.

Show More

70 views 1 answer







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

Show More

60 views 0 answers







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

Show More

106 views 1 answer







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

Show More

147 views 1 answer








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

Show More

70 views 1 answer








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

Show More

108 views 1 answer







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!

Show More

62 views 1 answer







Calculate the current if 12 coulombs of charge passes through a wire at a steady rate in 35 seconds

Show More

9 views 0 answers







The current zero interruption, in oil and air blast circuit breakers, is achieved by?
Last Answer : The current zero interruption, in oil and air blast circuit breakers, is achieved by lengthening of the gap, cooling and blast effect.

Show More

438 views 1 answer







A differential relay measures the vector difference between (a) two currents (b) two voltages (c) two or more similar electrical quantities (d) none of the above
Last Answer : (c) two or more similar electrical quantities

Show More

23 views 1 answer







With the help of neat diagram, explain operation of static relay.
Last Answer : Operation of Static Relay: Operation: 1) The solid-state component used are transistors, diodes, resistors, IC s, capacitor etc. The function of comparison and measurement are accomplished by ... ) An auxiliary dc supply is provided for operation of static relay elements as shown in figure.

Show More

110 views 1 answer







Describe the construction and Operation of Buchholz relay with neat labeled diagram.
Last Answer : Construction of Buchholz Relay: It takes the form of a domed vessel placed in the connecting pipe between the main tank and the conservator. The device has two elements. The upper element ... manner that it senses the sudden violent movement of oil/gas from transformer tank to conservator. 

Show More

231 views 1 answer






Show More⇦ PreviousNext ⇨