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
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2 answers
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May 8, 2018
by
anonymous
Reactance relay is normally preferred for protection against
Last Answer : Reactance relay is normally preferred for protection against earth faults
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120 views
1 answer
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Apr 29, 2018
by
anonymous
Last Answer : A Buchholz relay can be installed on oil cooled transformers.
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70 views
1 answer
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Mar 19, 2018
by
anonymous
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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
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627 views
1 answer
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May 1, 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.
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10 views
1 answer
asked
May 5, 2021
by
anonymous
main parts of Relay
Last Answer : Coil, plunger, contacts, springs, connecting terminals and enclosure.
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70 views
1 answer
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Aug 28, 2019
by
anonymous
What is phase failure relay and how it's work?
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60 views
0 answers
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Aug 12, 2019
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
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710 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
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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
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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.
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5.1k views
1 answer
asked
May 2, 2018
by
anonymous
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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
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117 views
1 answer
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Apr 30, 2018
by
anonymous
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
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496 views
1 answer
asked
Apr 29, 2018
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
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106 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
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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
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68 views
1 answer
asked
Apr 28, 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
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147 views
1 answer
asked
Apr 28, 2018
by
anonymous
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Last Answer : The torque produced in induction type relay (shaded pole structure) is inversely proportional to the square of the current.
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829 views
1 answer
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Mar 20, 2018
by
anonymous
Last Answer : Admittance relay is directional relay.
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154 views
1 answer
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Mar 20, 2018
by
anonymous
Last Answer : The relay with inverse time characteristic will operate within 5 to 10 sec.
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115 views
1 answer
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Mar 20, 2018
by
anonymous
Last Answer : The under voltage relay can be used for generators, busbars, transformers, motors.
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68 views
1 answer
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Mar 20, 2018
by
anonymous
Last Answer : Reactance relay is preferred for phase fault on short transmission line.
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110 views
1 answer
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Mar 20, 2018
by
anonymous
Last Answer : Induction cup relay is operated due to changes in current, voltage, impedance.
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352 views
1 answer
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Mar 20, 2018
by
anonymous
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.
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95 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.
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150 views
1 answer
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Mar 20, 2018
by
anonymous
Last Answer : A differential relay measures the vector difference between two or more similar electrical quantities.
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159 views
1 answer
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Mar 19, 2018
by
anonymous
Last Answer : Burden of a protective relay is the power absorbed by the circuit of relay.
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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.
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153 views
1 answer
asked
Mar 19, 2018
by
anonymous
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Last Answer : The relay operating speed depends upon the spring tension, the rate of flux built up, armature core air gap.
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271 views
1 answer
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Mar 19, 2018
by
anonymous
How do relay works ?
Last Answer : Relay working like contact it is noise less
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134 views
1 answer
asked
Dec 30, 2017
by
anonymous
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What is the use of Buchholz relay in transformer?
Last Answer : This is a transformer that is used to step up and down current.
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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 .
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110 views
1 answer
asked
Dec 17, 2017
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!
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62 views
1 answer
asked
Dec 4, 2017
by
anonymous
What are the uses of Buchholz’s relay?
Last Answer : Bucholz relay is used to give an alarm in case of incipient( slow-developing) faults in the transformer and to connect the transformer from the supply in the event of severe internal faults. It is usually used in oil immersion transformers with a rating over 750KVA.
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1 view
1 answer
Protection against sustained overloads occurring in molded-case circuit breakers is provided by a/an __________. A. overvoltage release B. thermal acting trip C. thermal overload relay D. current overload relay
Last Answer : Answer: B
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1 answer
What is the highest level of protection warning at a base?
Last Answer : What is the answer ?
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1 answer
There is sufficient plastic deformation prior to fatigue failure, which gives a warning well in advance. a) True b) False
Last Answer : b) False
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1 answer
The purpose of a magnetic relay is to _____________. A. open a circuit only in the event of overload B. remotely open and close contacts C. provide overcurrent protection during starting D. relay voltages at increased power
Last Answer : Answer: B
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2 views
1 answer
State any four relays used for catenary protection. State function of each relay.
Last Answer : Relays Used for Catenary Protection: 1. MHO relay: Wrong coupling protection. 2. MHO relay: Over current protection at farthest point. 3. Over current relay: Over current protection against faults near substation 4. Under voltage relay: Protection against faults far away from substation.
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176 views
1 answer
asked
Jul 19, 2019
by
anonymous
125 views
0 answers
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Nov 24, 2018
by
anonymous
Draw a neat sketch of earth fault protection of auxiliary circuit of electric loco. State the function of relay and isolating resistance.
Last Answer : Ans: Earth fault protection for auxiliaries in Loco: Function of relay: The earth fault occurring anywhere in the auxiliary circuit gets monitored by the relay which acts to trip the main CB. Function of ... star point to earth through a high resistance so that the relay operation is avoided.
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123 views
1 answer
asked
Sep 2, 2018
by
anonymous
A series resistance is added to the over-current relay in a bus bar differential protection scheme which: a. Helps to develop some voltage across it which otherwise should appear across the relay and is ... the effects of CT saturation and lowers the pickup value of the relay d. All of the above
Last Answer : A series resistance is added to the over-current relay in a bus bar differential protection scheme which: a. Helps to develop some voltage across it which otherwise should appear across the relay and is ... the effects of CT saturation and lowers the pickup value of the relay d. All of the above
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93 views
1 answer
asked
Sep 1, 2018
by
anonymous
The transmission line distance protection relay having the property of being inherently directional is (A) impedance relay (B) MHO relay (C) OHM relay (D) reactance relay
Last Answer : The transmission line distance protection relay having the property of being inherently directional is MHO relay
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457 views
1 answer
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May 25, 2018
by
anonymous
Mho relay is usually employed for protection of (A) Short lines (B) Medium lines (C) Long lines (D) Any line
Last Answer : Mho relay is usually employed for protection of long lines.
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628 views
2 answers
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Apr 14, 2018
by
anonymous
Which one of the following statements is NOT true of innate immunity? a. It is an early-warning system against pathogens. b. It is a form of immunity found only in vertebrates. c. It is a nonspecific response. d. It responds within minutes to many infections.
Last Answer : b. It is a form of immunity found only in vertebrates.
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3 views
1 answer
Does over load relay give 100% guarantee against the single phasing?
Last Answer : No. It depends on the motor load and the motor winding (star or delta).
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2 views
1 answer
How long will vaccines offer protection against covid?
Last Answer : I don't know the answer, I don't think anyone knows yet. Some more questions to add: are they suggesting a booster because they are considering actually changing the target of the vaccine because of ... virus. I think you mentioned a while back they were doing that type of study in some country.
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1 answer
asked
Mar 5
by
anonymous
It being quite common to use umbrellas as protection against rain, why is their use against sunlight and snowfall unheard of?
Last Answer : I see them in use in sunny weather every single day. I can look out my office window right now and see some. 100% guaranteed. They are even sold with a UV reflective material on the top.
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1 answer
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Mar 2
by
anonymous
Protection against obesity - How promising is nicotinamide riboside, a substance found in milk?
Last Answer : Wow! Intriguing. I would be very interested to see if high doses were OK and without side effects.
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1 answer
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Feb 27
by
anonymous
US law doesn't prohibit hate speech, as it's under the protection of the 1st amendment. Can you argue against this?
Last Answer : It can’t be not allowed, otherwise everything in the list of amendments or whatever you guys call it could be manipulated, twisted and seen as false, and it would all be pointless.
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1 answer
asked
Feb 27
by
anonymous
