McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 101. |
Oil switches are employed for |
| A. | low currents circuits |
| B. | low voltages circuits |
| C. | high voltages and large currents circuits |
| D. | all circuits |
| Answer» C. high voltages and large currents circuits | |
| 102. |
A switchgear is device used for |
| A. | interrupting an electrical circuit |
| B. | switching an electrical circuit 111. |
| C. | switching and controlling an electrical circuit |
| D. | switching, controlling and protecting the electrical circuit and equipment |
| Answer» D. switching, controlling and protecting the electrical circuit and equipment | |
| 103. |
The fuse wire, in D.C. circuits, is inserted in |
| A. | negative circuit only |
| B. | positive circuit only |
| C. | both (a) and (b) |
| D. | either (a) or (b) |
| Answer» C. both (a) and (b) | |
| 104. |
By which of the following methods major portion of the heat generated in a H.R.C. fuse is dissipated ? |
| A. | Radiation |
| B. | Convection |
| C. | Conduction |
| D. | All of the above |
| Answer» C. Conduction | |
| 105. |
A short-circuit is identified by |
| A. | no current flow |
| B. | heavy current flow |
| C. | voltage drop |
| D. | voltage rise |
| Answer» B. heavy current flow | |
| 106. |
The information to the circuit breaker under fault conditions is provided by |
| A. | relay |
| B. | rewirable fuse |
| C. | H.R.C. only |
| D. | all of the above |
| Answer» A. relay | |
| 107. |
To limit short-circuit current in a power system are used. |
| A. | earth wires |
| B. | isolators |
| C. | H.R.C. fuses |
| D. | reactors |
| Answer» D. reactors | |
| 108. |
A balanced 3-phase system consists of |
| A. | zero sequence currents only |
| B. | positive sequence currents only |
| C. | negative and zero sequence currents |
| D. | zero, negative and positive sequence currents |
| Answer» B. positive sequence currents only | |
| 109. |
In a single bus-bar system there will be complete shut down when |
| A. | fault occurs on the bus itself |
| B. | fault occurs on neutral line |
| C. | two or more faults occur simultaneously |
| D. | fault occurs with respect to earthing |
| Answer» A. fault occurs on the bus itself | |
| 110. |
Which device is used for protection of equipment from from damage caused by overload or short circuit? |
| A. | CVT |
| B. | Circuit Breaker |
| C. | Current Transformer |
| D. | Lighting Arrester |
| Answer» B. Circuit Breaker | |
| 111. |
Isolator in substation is open under ------------- condition? |
| A. | No load |
| B. | Short Circuit |
| C. | Full Load |
| D. | Any of the above |
| Answer» A. No load | |
| 112. |
Earthling switch is used for |
| A. | measuring of safety voltage |
| B. | protection of equipment from ground faults |
| C. | discharging residual energies |
| D. | all of the above |
| Answer» D. all of the above | |
| 113. |
If the time of operating of a relay for unity TMS is 10secs., the time of operation for 0.5 TMS will be |
| A. | 20 secs. |
| B. | 5 secs. |
| C. | 10 secs. |
| D. | None of the above |
| Answer» B. 5 secs. | |
| 114. |
A fault is more severe from the view point of RRRV if is a |
| A. | Short line fault. |
| B. | Medium length line fault. |
| C. | Long line fault. |
| D. | None of these. |
| Answer» A. Short line fault. | |
| 115. |
A reactance relay is |
| A. | Voltage restrained directional relay. |
| B. | Directional restrained over-current relay. |
| C. | Voltage restrained over-current relay. |
| D. | None of the above. |
| Answer» B. Directional restrained over-current relay. | |
| 116. |
For measuring positive, negative and zero sequence voltages in a system, the reference is taken as |
| A. | Neutral of the system only. |
| B. | Ground only. |
| C. | For zero sequence neutral and for positive and negative the ground. |
| D. | None of the above. |
| Answer» D. None of the above. | |
| 117. |
Positive, negative and zero sequence impedances of a solidly grounded system under steady state condition always follow the relations |
| A. | Z4>Z2>Z0 |
| B. | Z2>Z4>Z0 |
| C. | Z0>Z4>Z2 |
| D. | None of the above |
| Answer» C. Z0>Z4>Z2 | |
| 118. |
Phase comparators in case of static relays and electro-mechanical relays normally are |
| A. | Sine and cosine comparators respectively |
| B. | Cosine and sine comparators respectively. |
| C. | Both are cosine comparators. |
| D. | Both are sing comparators. |
| Answer» B. Cosine and sine comparators respectively. | |
| 119. |
For reducing tower footing resistance it is better to use |
| A. | Chemical and ground rods only. |
| B. | Chemical and counterpoise only. |
| C. | Ground rod and counterpoise only. |
| D. | Chemical, ground rods and counterpoise. |
| Answer» C. Ground rod and counterpoise only. | |
| 120. |
Rate of rise of restriking voltage depends |
| A. | Type of circuit breaker. |
| B. | Inductance of the system only. |
| C. | Capacitance of the system only. |
| D. | Inductance and capacitance of the system |
| Answer» D. Inductance and capacitance of the system | |
| 121. |
What is the purpose of back up protection? |
| A. | To increase the speed |
| B. | To increase the reach |
| C. | To leave no blind spot |
| D. | To guard against failure of primary |
| Answer» D. To guard against failure of primary | |
| 122. |
What is the actuating quantity for the relays? |
| A. | Magnitude |
| B. | Frequency |
| C. | Phase angle |
| D. | All of these |
| Answer» D. All of these | |
| 123. |
Protective relays can be designed to respond to |
| A. | Light intensity, impedance |
| B. | Temperature, resistance, reactance |
| C. | Voltage and current |
| D. | All of these |
| Answer» D. All of these | |
| 124. |
On what factor does the operating speed of the relay depend upon? |
| A. | Rate of flux built up |
| B. | Armature core air gap |
| C. | spring tension |
| D. | All of these |
| Answer» D. All of these | |
| 125. |
What does the third part consist of? |
| A. | Primary winding of a current CT which is connected in series with the line to be protected. |
| B. | Secondary of the CT and the operating coil. |
| C. | Tripping circuit. |
| D. | All of these. |
| Answer» C. Tripping circuit. | |
| 126. |
Which component ensures the safety of the line from damage? |
| A. | Relay |
| B. | Circuit breaker |
| C. | Bus bar |
| D. | Current tr |
| Answer» A. Relay | |
| 127. |
The tripping circuit is_ |
| A. | AC |
| B. | DC |
| C. | either AC or DC |
| D. | None of these |
| Answer» C. either AC or DC | |
| 128. |
Plug setting of a electromagnetic relay can be altered by varying |
| A. | Number of ampere turns |
| B. | Air gap of magnetic path |
| C. | Adjustable back stop |
| D. | None of these |
| Answer» A. Number of ampere turns | |
| 129. |
the most efficient torque producing actuating structure for the induction type relays is |
| A. | Shaded pole structure |
| B. | Watt hour meter structure |
| C. | Induction cup structure |
| D. | Single induction loop structure |
| Answer» C. Induction cup structure | |
| 130. |
If the power factor is zero, the active recovery voltage will be |
| A. | minimum |
| B. | 0.5 |
| C. | 0.707 |
| D. | Maximum. |
| Answer» D. Maximum. | |
| 131. |
Which of the following is not a part of the circuit breaker? |
| A. | Explosion pot |
| B. | Fixed and moving contacts |
| C. | Conservator |
| D. | Operating mechanism. |
| Answer» C. Conservator | |
| 132. |
Which of the following circuit breaker will produce the least arc energy? |
| A. | Minimum oil circuit breaker |
| B. | Air blast circuit breaker |
| C. | Plain oil circuit breaker |
| D. | All will produce same energy. |
| Answer» B. Air blast circuit breaker | |
| 133. |
For a circuit breaker 'break time' is |
| A. | Same as opening time |
| B. | Opening time + arc duration |
| C. | Opening time + arc duration + resistor current duration. |
| D. | none |
| Answer» C. Opening time + arc duration + resistor current duration. | |
| 134. |
The breaking capacity of a circuit breaker in MVA (3 phase) is given by |
| A. | Rated service voltage x rated symmetrical current |
| B. | 1.1 x rated service voltage x rated symmetrical current |
| C. | (2)1/2 x rated service voltage x rated symmetrical current |
| D. | (3)1/2x rated service voltage x rated symmetrical current. |
| Answer» D. (3)1/2x rated service voltage x rated symmetrical current. | |
| 135. |
Which relay is used for feeders? |
| A. | MHO relay |
| B. | Translay relay |
| C. | Merz price protection |
| D. | Buchholz relay. |
| Answer» B. Translay relay | |
| 136. |
Which of the following relays is used on transformers? |
| A. | Buchholz relay |
| B. | MHO relay |
| C. | Merz price relay |
| D. | None of the above. |
| Answer» A. Buchholz relay | |
| 137. |
MHO relay is used for |
| A. | Rectifiers |
| B. | Circuit breakers |
| C. | Transmission lines |
| D. | Feeders. |
| Answer» C. Transmission lines | |
| 138. |
Merz-price protection is used on |
| A. | Substations |
| B. | Capacitor bank |
| C. | Induction motor |
| D. | Generators. |
| Answer» D. Generators. | |
| 139. |
The values of fault current depend on |
| A. | Voltage at the faulty point |
| B. | Total impedance up to the fault |
| C. | Both (A) and (B) above |
| D. | None of the above |
| Answer» C. Both (A) and (B) above | |
| 140. |
The advantage of neutral earthling is |
| A. | Simplified design of earth fault protection |
| B. | Over-voltages due to lightning can be discharged to the earth |
| C. | Freedom from persistent arcing grounds |
| D. | all of the above. |
| Answer» D. all of the above. | |
| 141. |
The over-voltage surges in power systems may be caused by |
| A. | Lightning |
| B. | Switching |
| C. | Resonance |
| D. | Any of the above. |
| Answer» D. Any of the above. | |
| 142. |
The protection against over-voltage due to lightening is provided by |
| A. | Use of surge diverters |
| B. | Low tower footing resistance |
| C. | Use of overhead ground wires |
| D. | Any of the above. |
| Answer» D. Any of the above. | |
| 143. |
Which of the following is a conducting medium for electric current ? |
| A. | Low temperature gas |
| B. | High temperature gas |
| C. | Dissociated gas |
| D. | Plasma. |
| Answer» D. Plasma. | |
| 144. |
In circuit-breakers the contact space is ionized by |
| A. | Thermal ionization of gas |
| B. | Thermal emission from surface of contacts |
| C. | Field emission from the surface of contacts |
| D. | Any of the above. |
| Answer» D. Any of the above. | |
| 145. |
Which of the following are air-break switching devices ? |
| A. | Isolator |
| B. | Limit switch |
| C. | Earthling switch |
| D. | All of the above. |
| Answer» D. All of the above. | |
| 146. |
Which of the following statement about SF6 gas is incorrect? |
| A. | It is non-toxic gas |
| B. | It is non-inflammable |
| C. | It has density 5 times that of air at 200C |
| D. | It has dark yellow color. |
| Answer» D. It has dark yellow color. | |
| 147. |
SF6 gas is transported in |
| A. | Gas cylinders |
| B. | Liquid form in cylinders |
| C. | Solid form in boxes |
| D. | Air cylinders. |
| Answer» B. Liquid form in cylinders | |
| 148. |
duringarc extinction SF6 gas |
| A. | Decomposes into S and F ions |
| B. | Decomposes into SF4and SF2 |
| C. | Gets oxidized |
| D. | Reduces to SF3. |
| Answer» B. Decomposes into SF4and SF2 | |
| 149. |
Dielectric strength of SF6 is |
| A. | less than that of air at atmospheric pressure |
| B. | less than that of oil used in OCB |
| C. | more than that of oil used in OCB |
| D. | More at lower pressure and low at higher pressures. |
| Answer» B. less than that of oil used in OCB | |
| 150. |
Which of the following is the demerit of SF6 circuit breakers? |
| A. | Sealing problem of gas |
| B. | In flux of moisture in the gas system is dangerous |
| C. | Deterioration of quality of circuit breaker affects reliability of circuit breaker |
| D. | All of the above. |
| Answer» D. All of the above. | |
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