What is voltage interruption?
Show More
51 views
0 answers
asked
Mar 10, 2018
by
anonymous
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
asked
Sep 22, 2018
by
anonymous
.jpg)
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
asked
Mar 25, 2018
by
anonymous
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
asked
Mar 21, 2018
by
anonymous
.jpg)
Last Answer : For handling greater currents induction wattmeters are used in conjunction with current transformers.
Show More
139 views
1 answer
asked
Mar 21, 2018
by
anonymous
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
asked
Mar 20, 2018
by
anonymous
How eddy currents are generated?
Show More
69 views
0 answers
asked
Mar 14, 2018
by
anonymous
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
asked
May 8, 2018
by
anonymous
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
asked
May 8, 2018
by
anonymous
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
asked
May 3, 2018
by
anonymous
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
asked
May 3, 2018
by
anonymous
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
asked
May 2, 2018
by
anonymous
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
asked
May 1, 2018
by
anonymous
.jpg)
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
asked
Apr 30, 2018
by
anonymous
.jpg)
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
asked
Apr 29, 2018
by
anonymous
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
asked
Apr 29, 2018
by
anonymous
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
asked
Apr 28, 2018
by
anonymous
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
asked
Apr 28, 2018
by
anonymous
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
asked
Mar 20, 2018
by
anonymous
.jpg)
Last Answer : Admittance relay is directional relay.
Show More
154 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : The relay with inverse time characteristic will operate within 5 to 10 sec.
Show More
115 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : The under voltage relay can be used for generators, busbars, transformers, motors.
Show More
68 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : Reactance relay is preferred for phase fault on short transmission line.
Show More
110 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : Induction cup relay is operated due to changes in current, voltage, impedance.
Show More
352 views
1 answer
asked
Mar 20, 2018
by
anonymous
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
asked
Mar 20, 2018
by
anonymous
Last Answer : A differential relay measures the vector difference between two or more similar electrical quantities.
Show More
159 views
1 answer
asked
Mar 19, 2018
by
anonymous
Last Answer : Burden of a protective relay is the power absorbed by the circuit of relay.
Show More
810 views
1 answer
asked
Mar 19, 2018
by
anonymous
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
asked
Mar 19, 2018
by
anonymous
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
asked
Mar 19, 2018
by
anonymous
How do relay works ?
Last Answer : Relay working like contact it is noise less
Show More
134 views
1 answer
asked
Dec 30, 2017
by
anonymous
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
asked
Dec 17, 2017
by
anonymous
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
asked
Dec 17, 2017
by
anonymous
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
.jpg)
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
asked
Apr 29, 2018
by
anonymous
.jpg)
Last Answer : A sensitive galvanometer produces large deflection for a small value of current.
Show More
234 views
1 answer
asked
Mar 21, 2018
by
anonymous
Last Answer : Large capacity generators are invariably hydrogen cooled.
Show More
95 views
1 answer
asked
Mar 20, 2018
by
anonymous
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
asked
May 5, 2021
by
anonymous
main parts of Relay
Last Answer : Coil, plunger, contacts, springs, connecting terminals and enclosure.
Show More
70 views
1 answer
asked
Aug 28, 2019
by
anonymous
What is phase failure relay and how it's work?
Show More
60 views
0 answers
asked
Aug 12, 2019
by
anonymous
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
asked
Apr 29, 2018
by
anonymous
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
asked
Apr 28, 2018
by
anonymous
Last Answer : A Buchholz relay can be installed on oil cooled transformers.
Show More
70 views
1 answer
asked
Mar 19, 2018
by
anonymous
Last Answer : Buchholz's relay gives warning and protection against electrical fault inside the transformer itself.
Show More
108 views
1 answer
asked
Mar 19, 2018
by
anonymous
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
asked
Dec 4, 2017
by
anonymous
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
asked
Jun 3, 2021
by
barry
.jpg)
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
asked
Mar 19, 2018
by
anonymous
.jpg)
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
asked
Jun 23, 2020
by
anonymous
.jpg)
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
asked
Jun 23, 2020
by
anonymous
