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

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
by

1 Answer

Answer :

(c) constantly the electrical quantities which differ during normal and abnormal conditions
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Related questions

Protective relays are devices that detect abnormal conditions in electrical circuits by measuring?

Last 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.

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

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

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

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

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

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

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

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

Last Answer : (a) power

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

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

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

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)

A differential relay measures the vector difference between (a) two currents (b) two voltages (c) two or more similar electrical quantities (d) none of the above

Description : A differential relay measures the vector difference between (a) two currents (b) two voltages (c) two or more similar electrical quantities (d) none of the above

Last Answer : (c) two or more similar electrical quantities

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

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

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

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

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

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

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

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

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

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

D.C. shunt relays are made of (a) few turns of thin wire (b) few turns of thick wire (c) many turns of thin wire (d) many turns of thick wire

Description : D.C. shunt relays are made of (a) few turns of thin wire (b) few turns of thick wire (c) many turns of thin wire (d) many turns of thick wire

Last Answer : (c) many turns of thin wire

Overload relays are of...... type. (a) induction (b) solid state (c) thermal (d) electromagnetic (e) all above

Description : Overload relays are of...... type. (a) induction (b) solid state (c) thermal (d) electromagnetic (e) all above

Last Answer : (e) all above

Fault diverters are basically (a) fuses (b) relays (c) fast switches (d) circuit breakers

Description : Fault diverters are basically (a) fuses (b) relays (c) fast switches (d) circuit breakers

Last Answer : (c) fast switches

H.R.C. fuses provide best protection against (a) overload (b) reverse current (c) open-circuits (d) short-circuits

Description : H.R.C. fuses provide best protection against (a) overload (b) reverse current (c) open-circuits (d) short-circuits

Last Answer : (d) short-circuits

Circuit breakers are essentially (a) current carrying contacts called electrodes (b) arc extinguishers (c) circuits to break the system (d) transformers to isolate the two systems (e) any of the above

Description : Circuit breakers are essentially (a) current carrying contacts called electrodes (b) arc extinguishers (c) circuits to break the system (d) transformers to isolate the two systems (e) any of the above

Last Answer : (a) current carrying contacts called electrodes

Burden of a protective relay is the power (a) required to operate the circuit breaker (b) absorbed by the circuit of relay (c) developed by the relay circuit (d) none of the above

Description : Burden of a protective relay is the power (a) required to operate the circuit breaker (b) absorbed by the circuit of relay (c) developed by the relay circuit (d) none of the above

Last Answer : (b) absorbed by the circuit of relay

An efficient and a well designed protective relaying should have (a) good selectivity and reliability (b) economy and simplicity (c) high speed and selectivity (d) all of the above

Description : An efficient and a well designed protective relaying should have (a) good selectivity and reliability (b) economy and simplicity (c) high speed and selectivity (d) all of the above

Last Answer : (d) all of the above

The delay fuses are used for the protection of ________ . (a) motors (b) power outlet circuits (c) fluorescent lamps (d) light circuits

Description : The delay fuses are used for the protection of ________ . (a) motors (b) power outlet circuits (c) fluorescent lamps (d) light circuits

Last Answer : (a) motors

Arc in a circuit breaker is interrupted at (a) zero current (b) maximum current (c) minimum voltage (d) maximum voltage

Description : Arc in a circuit breaker is interrupted at (a) zero current (b) maximum current (c) minimum voltage (d) maximum voltage

Last Answer : (a) zero current

Induction cup relay is operated due to changes in (a) current (b) voltage (c) impedance (d) all of the above

Description : Induction cup relay is operated due to changes in (a) current (b) voltage (c) impedance (d) all of the above

Last Answer : (d) all of the above

The arc voltage produced in A.C. circuit breaker is always (a) in phase with the arc current (b) lagging the arc current by 90" (c) leading the arc current by 90° (d) none of the above

Description : The arc voltage produced in A.C. circuit breaker is always (a) in phase with the arc current (b) lagging the arc current by 90" (c) leading the arc current by 90° (d) none of the above

Last Answer : (a) in phase with the arc current

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

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)

In order that current should flow without causing excessive heating or voltage drop, the relay contacts should (a) have low contact resistance (b) be clean and smooth (c) be of sufficient size and proper shape (d) have all above properties

Description : In order that current should flow without causing excessive heating or voltage drop, the relay contacts should (a) have low contact resistance (b) be clean and smooth (c) be of sufficient size and proper shape (d) have all above properties

Last Answer : (d) have all above properties

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 absence of disease of the vasculature, there is a difference of no more than 5 mm Hg between arm pressures. b) must be equal in both arms. The pressures in each arm do not have to be equal in order to be considered normal. c) may vary 10 mm Hg or more between arms. Pressures that vary more than 10 mm Hg between arms indicate an abnormal finding. d) may vary, with the higher pressure found in the left arm. The left arm pressure is not anticipated to be higher than the right as a normal anatomical variant.

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.

What is re-striking voltage?

Description : What is re-striking voltage?

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

What is recovery voltage in circuit breaker?

Description : What is recovery voltage in circuit breaker?

Last Answer : Recovery voltage in circuit breakers is defined as the power frequency rms voltage which appears across the breaker contacts after the transient oscillations die out and the final extinction of the arc ... poles of the circuit breaker. It is the voltage developed after the arc extinction is competed

Series capacitors are used to (a) compensate for line inductive reactance (b) compensate for line capacitive reactance (c) improve line voltage (d) none of the above

Description : Series capacitors are used to (a) compensate for line inductive reactance (b) compensate for line capacitive reactance (c) improve line voltage (d) none of the above

Last Answer : (a) compensate for line inductive reactance

Over voltage protection is recommended for (a) hydro-electric generators (b) steam turbine generators (c) gas turbine generators (d) all of the above (e) none of the above

Description : Over voltage protection is recommended for (a) hydro-electric generators (b) steam turbine generators (c) gas turbine generators (d) all of the above (e) none of the above

Last Answer : (d) all of the above

The under voltage relay can be used for (a) generators (b) busbars (c) transformers (d) motors (e) all of the above

Description : The under voltage relay can be used for (a) generators (b) busbars (c) transformers (d) motors (e) all of the above

Last Answer : (e) all of the above

The short circuit in any winding of the transformer is the result of (a) mechanical vibration (b) insulation failure (c) loose connection (d) impulse voltage

Description : The short circuit in any winding of the transformer is the result of (a) mechanical vibration (b) insulation failure (c) loose connection (d) impulse voltage

Last Answer : (d) impulse voltage

The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to (a) lubricate the contacts (b) insulate the contacts from switch body (c) extinguish the arc (d) all of the above (e) none of the above

Description : The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to (a) lubricate the contacts (b) insulate the contacts from switch body (c) extinguish the arc (d) all of the above (e) none of the above

Last Answer : (c) extinguish the arc

Resistance grounding is used for voltage between (a) 33kVto66kV (b) HkVto33kV (c) 3.3kVandllkV (d) none of the above

Description : Resistance grounding is used for voltage between (a) 33kVto66kV (b) HkVto33kV (c) 3.3kVandllkV (d) none of the above

Last Answer : (c) 3.3kVandllkV

Which of the following is the least expensive protection for overcurrent is low voltage system ? (a) Rewireable fuse (b) Isolator (c) Oil circuit breaker (d) Air break circuit breaker (e) None of the above

Description : Which of the following is the least expensive protection for overcurrent is low voltage system ? (a) Rewireable fuse (b) Isolator (c) Oil circuit breaker (d) Air break circuit breaker (e) None of the above

Last Answer : (a) Rewireable fuse

Insulation resistance of high voltage circuit breakers is more than (a) 1 mega ohms (b) 10 mega ohms (c) 100 mega ohms (d) 500 mega ohms

Description : Insulation resistance of high voltage circuit breakers is more than (a) 1 mega ohms (b) 10 mega ohms (c) 100 mega ohms (d) 500 mega ohms

Last Answer : (c) 100 mega ohms

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

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

Arc in a circuit behaves as (a) a capackive reactance (b) an inductive reactance (c) a resistance increasing with voltage rise across the arc (d) a resistance decreasing with voltage rise across the arc

Description : Arc in a circuit behaves as (a) a capackive reactance (b) an inductive reactance (c) a resistance increasing with voltage rise across the arc (d) a resistance decreasing with voltage rise across the arc

Last Answer : (d) a resistance decreasing with voltage rise across the arc

A thermal protection switch can protect against (a) short-circuit (b) temperature (c) overload (d) over voltage

Description : A thermal protection switch can protect against (a) short-circuit (b) temperature (c) overload (d) over voltage

Last Answer : (c) overload

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

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

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

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

Devices which convert various physical quantities into electrical voltage are known as (a) Control system (b) sensors (c) level sensors (d) LDR

Description : Devices which convert various physical quantities into electrical voltage are known as (a) Control system (b) sensors (c) level sensors (d) LDR

Last Answer : (b) sensors

Why asymmetrical breaking current is higher than the symmetrical breaking current in a circuit breaker?

Description : Why asymmetrical breaking current is higher than the symmetrical breaking current in a circuit breaker?

Last Answer : Asymmetrical breaking current is the rms value of the combined sum of the dc and ac components of the short circuit current at the instant of separation of the breaker contacts while ... the ac component alone. Thus asymmetrical breaking current is higher than the symmetrical breaking current.

What is meant by Current Chopping?

Description : What is meant by Current Chopping?

Last Answer : Current Chopping is a phenomenon of current interruption before the natural current zero is reached.

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) times the A.C. component (d) The MVA at fault is equal to base MVA divided by per unit equivalent fault reactance

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

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

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

A transmission line is protected by (a) inrush protection (b) distance protection (c) time graded and current graded over current protection (d) both (b) and (c) (e) none of the above

Description : A transmission line is protected by (a) inrush protection (b) distance protection (c) time graded and current graded over current protection (d) both (b) and (c) (e) none of the above

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

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 (e) none of the above

Description : 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 (e) none of the above

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

Circuit breakers usually operate under (a) transient state of short-circuit current (b) sub-transient state of short-circuit current (c) steady state of short-circuit current (d) after D.C. component has ceased

Description : Circuit breakers usually operate under (a) transient state of short-circuit current (b) sub-transient state of short-circuit current (c) steady state of short-circuit current (d) after D.C. component has ceased

Last Answer : (a) transient state of short-circuit current