MCQOPTIONS
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MCQOPTIONS
This section includes 99 Mcqs, each offering curated multiple-choice questions to sharpen your Operating System knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Protective relays are devices that detect abnormal conditions inelectrical 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 |
| Answer» D. none of the above | |
| 2. |
The current zero interruption, in oil and air blast circuit breakers, is achieved by |
| A. | lengthening of the gap |
| B. | cooling and blast effect |
| C. | both (a) and (b) |
| D. | deionizing the oil with forced air |
| Answer» D. deionizing the oil with forced air | |
| 3. |
If the power factor is zero, the active recovery voltage will be |
| A. | minimum |
| B. | 0.5 |
| C. | 0.707 |
| D. | Maximum. |
| Answer» E. | |
| 4. |
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» E. | |
| 5. |
For which of the following ratings of the transformer differentialprotection is recommended ? |
| A. | above 30 kVA. |
| B. | equal to and above 5 MVA |
| C. | equal to and above 25 MVA |
| D. | none of the above |
| Answer» C. equal to and above 25 MVA | |
| 6. |
Ungrounded neutral transmission system is not recommendedbecause of system |
| A. | insulation being overstressed due to over voltages |
| B. | insulation overstress may lead to failure and subsequent phase to phase faults |
| C. | being inadequately protected against ground fault |
| D. | all of the above |
| Answer» E. | |
| 7. |
relay is preferred for phase fault on short transmission line. |
| A. | Induction type |
| B. | Reactance |
| C. | Impedance |
| D. | None of the above |
| Answer» C. Impedance | |
| 8. |
A _______ is used to measure the stator % winding temperature ofthe generator. |
| A. | thermocouple |
| B. | pyrometer |
| C. | resistance thermometer |
| D. | thermometer |
| Answer» D. thermometer | |
| 9. |
A.C. network analyser is used to solve problems of |
| A. | load flow |
| B. | load flow and short-circuit |
| C. | load flow and stability |
| D. | load flow, short-circuit and stability |
| Answer» E. | |
| 10. |
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» E. | |
| 11. |
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» E. | |
| 12. |
The inductive interference between power and communication linecan be minimized by |
| A. | transposition of the power line |
| B. | transposition of the communication line |
| C. | both (a) and (b) |
| D. | increasing the distance between the conductors |
| Answer» D. increasing the distance between the conductors | |
| 13. |
On which of the following effects of electric current a fuse operates ? |
| A. | Photoelectric effect |
| B. | Electrostatic effect |
| C. | Heating effect |
| D. | Magnetic effect |
| Answer» D. Magnetic effect | |
| 14. |
Overload relays are of…… type. |
| A. | induction |
| B. | solid state |
| C. | thermal |
| D. | all above |
| Answer» E. | |
| 15. |
For cost and safety, the outdoor substations are installed for voltagesabove |
| A. | 11 kV |
| B. | 33 kV |
| C. | 60kV |
| D. | 110kV |
| Answer» C. 60kV | |
| 16. |
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» C. Voltage restrained over-current relay. | |
| 17. |
The reflection co-efficient at the open circuited end of a transmissionline. |
| A. | zero |
| B. | infinity |
| C. | unity |
| D. | none of the above |
| Answer» D. none of the above | |
| 18. |
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» D. None of the above | |
| 19. |
Thermal overload relays are used to protect the motor against overcurrent due to |
| A. | short-circuits |
| B. | heavy loads |
| C. | grounds |
| D. | all of the above |
| Answer» C. grounds | |
| 20. |
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» D. none | |
| 21. |
Air blast circuit breakers for 400 kV power system are designed tooperate in |
| A. | 100 microsecond |
| B. | 50 millisecond |
| C. | 0.5 sec |
| D. | 0.1 sec |
| Answer» C. 0.5 sec | |
| 22. |
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» E. | |
| 23. |
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» E. | |
| 24. |
The over-voltage surges in power systems may be caused by |
| A. | Lightning |
| B. | Switching |
| C. | Resonance |
| D. | Any of the above. |
| Answer» E. | |
| 25. |
What is the actuating quantity for the relays? |
| A. | Magnitude |
| B. | Frequency |
| C. | Phase angle |
| D. | All of these |
| Answer» E. | |
| 26. |
Which device is used for protection of equipment from from damagecaused by overload or short circuit? |
| A. | CVT |
| B. | Circuit Breaker |
| C. | Current Transformer |
| D. | Lighting Arrester |
| Answer» C. Current Transformer | |
| 27. |
For measuring positive, negative and zero sequence voltages in asystem, 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» E. | |
| 28. |
MHO relay is used for |
| A. | Rectifiers |
| B. | Circuit breakers |
| C. | Transmission lines |
| D. | Feeders. |
| Answer» D. Feeders. | |
| 29. |
For which of the following protection from negative sequencecurrents is provided? |
| A. | Generators |
| B. | Motors |
| C. | Transmission line |
| D. | Tr |
| Answer» B. Motors | |
| 30. |
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» E. | |
| 31. |
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» E. | |
| 32. |
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» E. | |
| 33. |
Phase comparators in case of static relays and electro-mechanical relaysnormally are |
| A. | Sine and cosine comparators respectively |
| B. | Cosine and sine comparators respectively. |
| C. | Both are cosine comparators. |
| D. | Both are sing comparators. |
| Answer» C. Both are cosine comparators. | |
| 34. |
Isolator in substation is open under ------------- condition? |
| A. | No load |
| B. | Short Circuit |
| C. | Full Load |
| D. | Any of the above |
| Answer» B. Short Circuit | |
| 35. |
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» D. None of the above | |
| 36. |
Which of the following circuit breakers has high reliability andminimum maintenance ? |
| A. | Air blast circuit breakers |
| B. | Circuit breaker with SF6 gas |
| C. | Vacuum circuit breakers |
| D. | Oil circuit breakers |
| Answer» C. Vacuum circuit breakers | |
| 37. |
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» B. MHO relay | |
| 38. |
The interaction between a transmission line and communication lineis minimized by |
| A. | transposing transmission as well as communication lines |
| B. | increasing the height of the trans-mission line tower |
| C. | increasing the distance between the two lines |
| D. | all of the above |
| Answer» E. | |
| 39. |
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» C. more than that of oil used in OCB | |
| 40. |
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» E. | |
| 41. |
To limit short-circuit current in a power system are used. |
| A. | earth wires |
| B. | isolators |
| C. | H.R.C. fuses |
| D. | reactors |
| Answer» E. | |
| 42. |
duringarc extinction SF6 gas |
| A. | Decomposes into S and F ions |
| B. | Decomposes into SF4and SF2 |
| C. | Gets oxidized |
| D. | Reduces to SF3. |
| Answer» C. Gets oxidized | |
| 43. |
Which component ensures the safety of the line from damage? |
| A. | Relay |
| B. | Circuit breaker |
| C. | Bus bar |
| D. | Current tr |
| Answer» B. Circuit breaker | |
| 44. |
On which of the following routine tests are conducted? |
| A. | Oil circuit breakers |
| B. | Air blast circuit breakers |
| C. | Minimum oil circuit breakers |
| D. | All of the above |
| Answer» E. | |
| 45. |
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» D. All of these. | |
| 46. |
Which of the following parameter can be neglected for a short line ? |
| A. | Inductance |
| B. | Capacitance |
| C. | Resistance |
| D. | Reactance |
| Answer» C. Resistance | |
| 47. |
Which of the following are air-break switching devices ? |
| A. | Isolator |
| B. | Limit switch |
| C. | Earthling switch |
| D. | All of the above. |
| Answer» E. | |
| 48. |
To protect most of the electrical equipment handling low power, thetypes of relays used are |
| A. | thermocouple |
| B. | electronic and bimetallic |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» D. none of the above | |
| 49. |
By which of the following methods major portion of the heatgenerated in a H.R.C. fuse is dissipated ? |
| A. | Radiation |
| B. | Convection |
| C. | Conduction |
| D. | All of the above |
| Answer» D. All of the above | |
| 50. |
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» B. Air gap of magnetic path | |