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

1 Answer

Answer :

(a) Lightning arresters

Related questions

Description : Which of the following statements is incorrect? (a) Station batteries are used to operate relay only (b) The lightning arresters are basically surge diverters (c) An impedance relay has maximum fault current when fault occurs near the relay (d) A high speed relay has an operation of 1 to 2 cycles

Last Answer : (a) Station batteries are used to operate relay only

Description : Which of the following statements is incorrect ? (a) Lightning arrestors are used before the switchgear (b) Shunt reactors are used as compensation reactors (c) The peak short current is (1.8 xV2) ... component (d) The MVA at fault is equal to base MVA divided by per unit equivalent fault reactance

Last Answer : (a) Lightning arrestors are used before the switchgear

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

Description : What will be the reflection coefficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ? (a) Zero (b) Unity (c) Infinity (d) None of the above

Last Answer : (a) Zero

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

Description : Directional relays are based on flow of (a) power (b) current (c) voltage wave (d) all of the above

Last Answer : (a) power

Description : Relays can be designed to respond to changes in (a) resistance, reactance or impedance (b) voltage and current (c) light intensity (d) temperature (e) all above

Last Answer : (e) all above

Description : The voltage appearing across the contacts after opening of the circuit breaker is called______voltage. (a) recovery (b) surge (c) operating (d) arc (e) none of the above

Last Answer : (a) recovery

Description : relays are used for phase faults on long line. (a) Impedance (b) Reactance (c) Either of the above (d) None of the above

Last Answer : (a) Impedance

Description : When a transmission line is energized, the wave that propagates on it is (a) current wave only (b) voltage wave only (c) both (a) and (b) (d) power factor wave only

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

Description : The single phasing relays are used for the protection of (a) single phase motors only (b) two phase motors only (c) two single phase motors running in parallel (d) three phase motors

Last Answer : (d) three phase motors

Description : Distance relays are generally (a) split-phase relays (b) reactance relays (c) impedance relays (d) none of the above

Last Answer : (d) none of the above

Description : Discrimination between main and back up protection is provided by the use of relays which are (a) fact (b) sensitive (c) slow (d) none of the above

Last Answer : (c) slow

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

Description : 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

Last Answer : (a) merz price percentage differential protection

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Last Answer : (d) impulse voltage

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Last Answer : (a) Open circuit

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Last Answer : (d) all of the above

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Last Answer : (c) unity

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Last Answer : (a) short transmission line

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Last Answer : A travelling wave of surge resistance, Ro on a transmission line is terminated by a load resistance, RL. If RL > Ro then there is partial reflection of reversal of current only

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Last Answer : (a) compensate for line inductive reactance

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Last Answer : (b) generator transformer of the power plant

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Last Answer : (b) equal to and above 5 MVA

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Last Answer : The Re-striking voltage may be defined as the resultant transient voltage which appears across the breaker contacts at the instant of arc extinction

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