136 views

1 Answer

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.

Like 0 like

Please log in or register to answer this question.

Related questions

55 views

Description : Protective relays are devices that detect abnormal conditions in electrical circuits by measuring (a) current during abnormal condition (b) voltage during abnormal condition (c) constantly the electrical quantities which differ during normal and abnormal conditions (d) none of the above

Last Answer : (c) constantly the electrical quantities which differ during normal and abnormal conditions

1 answer
109 views

Last Answer : To protect most of the electrical equipment handling low power, the types of relays used are thermocouple, electronic and bimetallic.

1 answer
128 views

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

1 answer
815 views

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

1 answer
138 views

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

1 answer
3.1k views

Description : IDMT relays are used to protect the transformer against :  (A) Internal short -circuits (B) Open circuits (C) External short circuits (D) Oil leakage

Last Answer : IDMT relays are used to protect the transformer against : External short circuits

1 answer
2.6k views

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

1 answer
313 views

Last Answer : The single phasing relays are used for the protection of three phase motors.

1 answer
86 views

Last Answer : Impedance relays are used for phase faults on long line.

1 answer
400 views

Last Answer : Discrimination between main and back up protection is provided by the use of relays which are slow.

1 answer
168 views

Last Answer : Directional relays are based on flow of power.

1 answer
2.7k views

Description : D.C. shunt relays are made of?

Last Answer : D.C. shunt relays are made of many turns of thin wire.

1 answer
267 views

Last Answer : Thermal overload relays are used to protect the motor against overcurrent due to heavy loads.

1 answer
79 views

Last Answer : Overload relays are of induction, solid state, thermal, electromagnetic type.

1 answer
148 views

Last Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.

1 answer
50 views

Description : How many types of types of relays are there?

0 answers
137 views

Description : Consider the following statements. Which of these statements are correct ?  (1) Reactance relays are preferred for ground fault relaying  (2) Impedance relays are most suitable for:protecting long transmission lines  (3) Mho relays are best ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)

Last Answer : Consider the following statements. Which of these statements are correct ?  (1) Reactance relays are preferred for ground fault relaying  (2) Impedance relays are most suitable for:protecting long transmission lines  (3) Mho relays are ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)

1 answer
126 views

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. 

1 answer
3 views

Description : On an engine throttle control system, the auxiliary control circuits are provided with devices to prevent excessive overtravel of the pilot valve by the synchronous motor. These devices are called _________________. A. overlap sensors B. limit switches C. overtravel relays D. proximity switches

Last Answer : Answer: B

1 answer
81 views

Description : Electrical contact materials used in switches, brushes and relays must possess   (A) high thermal conductivity and high melting point  (B) Low thermal conductivity and low melting point   (C) High thermal conductivity and low melting point  (D) Low thermal conductivity and high melting point.

Last Answer : Electrical contact materials used in switches, brushes and relays must possess high thermal conductivity and high melting point 

1 answer
6 views

Description : The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Last Answer : Ans: A

1 answer
4 views

Description : What are the functions of protective relays

Last Answer : To detect the fault and initiate the operation of the circuit breaker to isolate the defective element from the rest of the system, thereby protecting the system from damages consequent to the fault.

1 answer
135 views

Description : Differential relays detect internal faults in 3-phase transformers by (A) zero sequence currents (B) positive sequence currents (C) negative sequence currents (D) both positive and negative sequence currents

0 answers
513 views

Description :  For the protection of parallel feeders fed from one end, the relays used are: A) non-directional relays at the source-end and directional relays at the load-end B) non-directional relays at both the ... at the source-end and non-directional at the load-end D) directional relays at both the ends

Last Answer : For the protection of parallel feeders fed from one end, the relays used are: non-directional relays at the source-end and directional relays at the load-end

1 answer
127 views

Description : Reactance relays are employed for Phase faults in : (A) Short lines (B) Medium lines (C) Long lines (D) Any line

Last Answer : Reactance relays are employed for Phase faults in : Short lines

1 answer
0 views

Description : Do relays use high voltage to control low currant circuits?

Last Answer : Low voltage to operate relay controlling high CURRENT circuits(currant is a dried fruit).

1 answer
0 views

Description : Do relays use high voltage to control low currant circuits?

Last Answer : Low voltage to operate relay controlling high CURRENT circuits(currant is a dried fruit).

1 answer
2 views

Description : Motor controllers are seldom troubled by grounds because ________________. A. cabinet heaters always keep internal components dry B. special insulation is used on wire for vital circuits C. ... on controller panels greatly reduce vibration D. contactors and relays are mounted on nonconducting panels

Last Answer : Answer: D

1 answer
17 views

Description : The inverse definite mean time relays are used for over current and earth fault protection of transformer against (a) heavy loads (b) internal short-circuits (c) external short-circuits (d) all of the above

Last Answer : (b) internal short-circuits

1 answer
24 views

Description : Thermal overload relays are used to protect the motor against over current due to (a) short-circuits (b) heavy loads (c) grounds (d) all of the above

Last Answer : (b) heavy loads

1 answer
1 view

Description : Routine A.C. motor maintenance should include periodic ______________. A. thermometer readings at normal loads to detect abnormal temperature rises B. inspection of the motor's internals for loose rotor bars ... C. bearing replacement each year using sealed units if available D. all of the above

Last Answer : Answer: A

1 answer
203 views

Description : State four functions of protective system.

Last Answer : Functions of Protective System:  1) To switch ON or OFF the electric power during normal conditions for operation and maintenance.  2) To protect the power system by isolating the faulty ... major faults.  7) To ensure maximum safety conditions from generation stage to consumers premises.

1 answer
108 views

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

1 answer
24 views

Description : Give the names of different electrical temperature measuring devices.

Last Answer : Electrical temperature measuring devices: RTD, thermocouple, thermistor

1 answer
109 views

Description : For integrated circuits photolithography is used to remove areas of a protective layer so that (a) Chemical reactions can take place in exposed areas. (b) Chemical reactions can take place in ... can take place in transparent areas. (d) Chemical reactions can take place in translucent areas.

Last Answer : Chemical reactions can take place in exposed areas

1 answer
26 views

Description : Which of the following devices will receive voltage surge first travelling on the transmission line ? (a) Lightning arresters (b) Relays (c) Step-down transformer (d) Switchgear

Last Answer : (a) Lightning arresters

1 answer
12 views

Description : When measuring the blood pressure in each of the patient's arms, the nurse recognizes that in the normal adult, the pressures a) differ no more than 5 mm Hg between arm pressures. Normally, in ... . The left arm pressure is not anticipated to be higher than the right as a normal anatomical variant.

Last Answer : a) differ no more than 5 mm Hg between arm pressures. Normally, in the absence of disease of the vasculature, there is a difference of no more than 5 mm Hg between arm pressures.

1 answer
11 views

Description : To protect most of the electrical equipment handling low power, the types of relays used are (a) thermocouple (b) electronic and bimetallic (c) both (a) and (b) (d) none of the above

Last Answer : (c) both (a) and (b)

1 answer
1 view

Description : What protective devices can be used for infection control?

Last Answer : What is the answer ?

1 answer
3 views

Description : Complete controller maintenance includes _____________. A. periodic testing of protective devices B. checking for loose or worn contacts and weak springs C. maintaining a sufficient supply of spare parts D. all of the above

Last Answer : Answer: D

1 answer
1 view

Description : A three-phase, induction-type motor experiences an open in one phase. Which of the listed automatic protective devices will prevent the machine from being damaged? A. Overspeed trip B. Thermal overload relay C. Three-pole safety switch D. Magnetic blowout coil

Last Answer : Answer: B

1 answer
11 views

Description : Draw a potentiometer temp. Measuring circuits and explain its?  

Last Answer : OPERATION : The input to the instrument is a measurement of some in the processes using a sensing element ( such as thermocouple ) or a device to produce direct voltage, which is the voltage (signal) ... to zero results ( null point ) the balancing ( servo motor is be longer driven )   

1 answer
5 views

Description : What area of an ohmmeter scale should be used when measuring circuits?

Last Answer : The middle of the scale.

1 answer
12 views

Description : High sensitive DC voltmeter provides accurate reading when measuring ___ circuits.

Last Answer : high resistance

1 answer
6 views

Description : High sensitive DC voltmeter provides accurate reading when measuring ___ circuits.

Last Answer : high resistance

1 answer
2 views

Description : A common type of protective covering used on electrical conductors is _____________. A. plain paper B. fibrous braid C. silver sheathing D. babbitt sheathing

Last Answer : Answer: B

1 answer
349 views

Description : List any four internal causes for abnormal operation of electrical equipment’s. 

Last Answer : Internal causes:- 1. Open circuit 2. Short circuit 3. Earth fault 4. Loose connection 5. Deposit of dirt and dust near ventilation passage 6. Low insulation resistance 7. Improper maintenance 8. Poor ... problems 13. Failure of cooling system 14. Excess wear and tear of internal parts 15. Ageing.

1 answer
1 view

Description : Which of the following devices can be used to detect radiant heat? (1) Liquid thermometer (2) Six's maximum and minimum thermometer (3) Constant volume air thermometer (4) Thermopile

Last Answer : (4) Thermopile Explanation: Based on the thermoelectric effect, the thermopile can be used as a heat sensor to measure thermal radiation. A thermopile is made of thermocouple junction pairs connected electrically in series. Thermocouples near the ground measures radiant energy.

1 answer
...