What is meant by Current Chopping?

What is meant by Current Chopping?
by

1 Answer

Answer :

Current Chopping is a phenomenon of current interruption before the natural current zero is reached.
by

Related questions

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.

For an Resistive Load and Inductive load considered for switching operation of circuit breaker, Switching of which load is difficult and Why?

Description : For an Resistive Load and Inductive load considered for switching operation of circuit breaker, Switching of which load is difficult and Why?

Last Answer : In case of switching resistive load, current and voltage will be in phase i.e,when during current zero voltage also will be zero in case of resistive load. Hence the voltage at the ... maximum. This results in re-striking of arc once again. Therefore switching inductive load will be difficult

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

When does an arc extincts?

Description : When does an arc extincts?

Last Answer : If the rate of rise of re-striking voltage (RRRV) is less than rate of rise of dielectric strength between the breaker contacts arc will not sustain and extincts

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

Why Isolation switches are provided along with the circuit breakers?

Description : Why Isolation switches are provided along with the circuit breakers?

Last Answer : Isolation switches are provided for separating the disconnected element from the live portion of the system for the purpose of safety

Air Blast Circuit Breakers Advantages Disadvantages

Description : Air Blast Circuit Breakers Advantages Disadvantages

Last Answer : Air Blast Circuit Breakers Advantages Disadvantages In air blast circuit breakers, compressed air at a pressure of 20-30 kg/cm2 is employed as an arc quenching medium. Air blast circuit breakers ... air blast circuit breaker current chopping problem exists There is a problem of re-striking voltage

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

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

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

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

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

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

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

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

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

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)

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)

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

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 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

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

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

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

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

The material used for fuse must have (a) low melting point and high specific resistance (b) low melting point and -low specific resistance (c) high melting point and low specific resistance (d) low melting point and any specific resistance

Description : The material used for fuse must have (a) low melting point and high specific resistance (b) low melting point and -low specific resistance (c) high melting point and low specific resistance (d) low melting point and any specific resistance

Last Answer : (a) low melting point and high specific resistance

Admittance relay is _______ relay. (a) impedance (b) directional (c) non-directional (d) none of the above

Description : Admittance relay is _______ relay. (a) impedance (b) directional (c) non-directional (d) none of the above

Last Answer : (b) directional

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

Overfluxing protection is recommended for (a) distribution transformer (b) generator transformer of the power plant (c) auto-transformer of the power plant (d) station transformer of the power plant

Description : Overfluxing protection is recommended for (a) distribution transformer (b) generator transformer of the power plant (c) auto-transformer of the power plant (d) station transformer of the power plant

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

Air blast circuit breakers for 400 kV power system are designed to operate in (a) 100 microsecond (b) 50 millisecond (c) 0.5 sec (d) 0.1 sec

Description : Air blast circuit breakers for 400 kV power system are designed to operate in (a) 100 microsecond (b) 50 millisecond (c) 0.5 sec (d) 0.1 sec

Last Answer : (b) 50 millisecond

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

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

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

transmission line has reflection coefficient as one. (a) Open circuit (b) Short-circuit (e) Long (d) None of the above

Description : transmission line has reflection coefficient as one. (a) Open circuit (b) Short-circuit (e) Long (d) None of the above

Last Answer : (a) Open circuit

Which of the following circuit breakers has high reliability and minimum maintenance ? (a) Air blast circuit breakers (b) Circuit breaker with SF6 gas (c) Vacuum circuit breakers (d) Oil circuit breakers

Description : Which of the following circuit breakers has high reliability and minimum maintenance ? (a) Air blast circuit breakers (b) Circuit breaker with SF6 gas (c) Vacuum circuit breakers (d) Oil circuit breakers

Last Answer : (b) Circuit breaker with SF6 gas

Series reactors should have (a) low resistance (b) high resistance (c) low impedance (d) high impedance

Description : Series reactors should have (a) low resistance (b) high resistance (c) low impedance (d) high impedance

Last Answer : (a) low resistance

Which of the following parameter can be neglected for a short line ? (a) Inductance (b) Capacitance (c) Resistance (d) Reactance

Description : Which of the following parameter can be neglected for a short line ? (a) Inductance (b) Capacitance (c) Resistance (d) Reactance

Last Answer : (b) Capacitance

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

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

The relay with inverse time characteristic will operate within (a) 1.5 sec (b) 5 to 10 sec (c) 5 to 20 sec (d) 20 to 30 sec (e) none of the above

Description : The relay with inverse time characteristic will operate within (a) 1.5 sec (b) 5 to 10 sec (c) 5 to 20 sec (d) 20 to 30 sec (e) none of the above

Last Answer : (b) 5 to 10 sec

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

A _______ is used to measure the stator % winding temperature of the generator. (a) thermocouple (b) pyrometer (c) resistance thermometer (d) thermometer

Description : A _______ is used to measure the stator % winding temperature of the generator. (a) thermocouple (b) pyrometer (c) resistance thermometer (d) thermometer

Last Answer : (c) resistance thermometer

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

Description : 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

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

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

relay is preferred for phase fault on short transmission line. (a) Induction type (b) Reactance (c) Impedance (d) None of the above

Description : relay is preferred for phase fault on short transmission line. (a) Induction type (b) Reactance (c) Impedance (d) None of the above

Last Answer : (b) Reactance

For which of the following protection from negative sequence currents is provided ? (a) Generators (b) Motors (c) Transmission line (d) Transformers

Description : For which of the following protection from negative sequence currents is provided ? (a) Generators (b) Motors (c) Transmission line (d) Transformers

Last Answer : (a) Generators

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

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

For cost and safety, the outdoor substations are installed for voltages above (a) 11 kV (b) 33 kV (c) 60kV (d) 110kV

Description : For cost and safety, the outdoor substations are installed for voltages above (a) 11 kV (b) 33 kV (c) 60kV (d) 110kV

Last Answer : (b) 33 kV

Bus coupler is very essential in arrangement (a) single bus (b) double bus, double breaker (c) main and transfer bus (d) all of the above

Description : Bus coupler is very essential in arrangement (a) single bus (b) double bus, double breaker (c) main and transfer bus (d) all of the above

Last Answer : (c) main and transfer bus

To reduce short circuit fault currents are used. (a) reactors (b) resistors (c) capacitors (d) none of the above

Description : To reduce short circuit fault currents are used. (a) reactors (b) resistors (c) capacitors (d) none of the above

Last Answer : (a) reactors

Short-circuit currents are due to (a) single phase to ground faults (b) phase to phase faults (c) two phase to ground faults (d) three phase faults (e) any of these

Description : Short-circuit currents are due to (a) single phase to ground faults (b) phase to phase faults (c) two phase to ground faults (d) three phase faults (e) any of these

Last Answer : (e) any of these