MCQ 1 In the following figure, the relay circuit is divided into three parts. What does the first 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) None of these

MCQ 25 The time of closing the cycle, in modern circuit breakers is

(A) 0.001 sec (B) 0.003 sec (C) 0.010 sec (D) 0.10 sec

MCQ 2 The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to

(A) Extinguish the arc (B) Insulate the contacts from switch body (C) Lubricate the contacts (D) None of the above

MCQ 3 Discrimination between main and back up protection is provided by the use of relays which are

(A) Slow (B) Fast (C) Sensitive (D) None of the above

MCQ 4 Which of the following statements is incorrect?

(A) Shunt reactors are used as compensation reactors (B) Lightning arrestors are used before the switchgear (C) The peak short current is (1.8 xV2) times the A component (D) The MVA at fault is equal to base MVA divided by per unit equivalent fault reactance

MCQ 24 A network analyser is used to solve problems of

(A) Load flow (B) Load flow, short-circuit and stability (C) Load flow and stability (D) Load flow and short-circuit

MCQ 5 Relays are used for phase faults on long line.

(A) Reactance (B) Impedance (C) Both (A) and (B) (D) None of the above

MCQ 18 The single phasing relays are used for the protection of

(A) Two phase motors only (B) Two single phase motors running in parallel (C) Three phase motors (D) Single phase motors only

MCQ 6 Series reactors must have

(A) Low resistance (B) High reatance (C) Low impedance (D) High impedance

MCQ 7 What is the average rate of rise of restriking voltage upto the first peak?

(A) 525 × 10³ kV / sec (B) 453 × 10³ kV / sec (C) 582 × 10³ kV / sec (D) 467 × 10³ kV / sec

MCQ 19 What is the making capacity of the circuit breaker?

(A) Less than the asymmetrical breaking capacity of the breaker (B) Greater than the asymmetrical breaking capacity of the breaker (C) Equal to the asymmetrical breaking capacity of the breaker (D) Equal to the symmetrical breaking capacity of the breaker

MCQ 8 Which of the following circuit breakers is used for the railway electrification?

(A) Air blast circuit breaker (B) SF₆ circuit breaker (C) Bulk oil circuit breaker (D) Minimum oil circuit breaker

MCQ 9 The breaking capacity of a three phase circuit breaker is given by

(A) Service line voltage × rated symmetrical current in amperes × 10^-6 MVA (B) √3 × Service line voltage × rated symmetrical current in amperes × 10^-6 MVA (C) 1.1 × Service line voltage × rated symmetrical current in amperes × 10^-6 MVA (D) √2 × Service line voltage × rated symmetrical current in amperes × 10^-6 MVA

MCQ 10 What is the cut off current in the fuse?

(A) Maximum value actually reached (B) Rms value actually reached (C) Average value actually reached (D) None of the above

MCQ 11 In a short circuit test on a circuit breaker, the following readings were obtained on single frequency transients Time to reach the peak re striking voltage ? 50μ sec, the peak re striking voltage, 100 kV, what is its average RRRV?

(A) 2 × 10⁶ kV/sec (B) 3 × 10⁵ kV/sec (C) 2 × 10⁵ kV/sec (D) 3 × 10⁶ kV/sec

MCQ 20 Recovery voltage is the value of rms voltage that reappears across the poles of a circuit breaker before_______________

(A) Restriking voltage (B) Final arc extinction (C) Rise of voltage (D) All of the above

MCQ 12 In a circuit breaker, the active recovery voltage depends upon which among these?

(A) Circuit conditions (B) Power factor (C) Both (A) and (B) (D) None of the above

MCQ 13 The heat produced at the contact point owing to flow of electric current is least affected by_____________.

(A) Temperature of the surrounding medium (B) Contact resistance (C) Magnitude of electric current flowing (D) Duration of flow of current

MCQ 21 Which type of tripping is generally preferred for the circuit breaker?

(A) Manual (B) Automatically (C) Depending on the voltage level (D) None of the above

MCQ 14 In a HRC fuse what is the time between the cut off and the final current zero called?

(A) Pre - arcing time (B) Arcing time (C) Total operating time (D) None of these

MCQ 15 The power loss is an important factor for the design of

(A) Transmission line (B) Motor (C) Generator (D) Feeder

MCQ 22 For which of the following ratings of the transformer differential protection 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

MCQ 16 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

MCQ 23 Large internal faults are protected by

(A) Merz-price percentage differential protection (B) Mho and ohm relays (C) Horn gaps and temperature relays (D) Earth fault and positive sequence relays

MCQ 17 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