The ground wire should not be smaller than No ______ copper.

The main function of a fuse is to

On which of the following routine tests are conducted ?

SF6 gas

The arcing contacts in a circuit breaker are made of

Which of the following medium is employed for extinction of arc in air circuit breaker ?

With which of the following, a circuit breaker must be equipped for remote operation ?

Fault diverters are basically

A thermal protection switch can protect against

Arc in a circuit behaves as

Thermal circuit breaker has

Relays can be designed to respond to changes in

Overload relays are of…… type.

Thermal overload relays are used to protect the motor against over current due to

Magnetic circuit breaker has ______ trip action.

D.C. shunt relays are made of

The relay operating speed depends upon

In order that current should flow without causing excessive heating or voltage drop, the relay contacts should

Circuit breakers usually operate under

Circuit breakers are essentially

The current zero interruption, in oil and air blast circuit breakers, is achieved by

Air blast circuit breaker is used for

An efficient and a well designed protective relaying should have

Burden of a protective relay is the power

Directional relays are based on flow of

A differential relay measures the vector difference between

A transmission line is protected by

Large internal faults are protected by

When a transmission line is energized, the wave that propagates on it is

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

The voltage appearing across the contacts after opening of the circuit breaker is called______voltage.

Ionization in circuit breaker is facilitated by

In a circuit breaker the basic problem is to

Overheating of relay contacts or contact born out is due to

Interruption of large currents by relay requires

Shunt capacitance is neglected while considering

The arc voltage produced in A.C. circuit breaker is always

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

Insulation resistance of high voltage circuit breakers is more than

H.R.C. fuses provide best protection against

The delay fuses are used for the protection of ________ .

Which of the following is the least expensive protection for overcurrent is low voltage system ?

Resistance grounding is used for voltage between

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

To protect most of the electrical equipment handling low power, the types of relays used are

Wave trap is used to trap waves of

Ungrounded neutral transmission system is not recommended because of system

The reflection co-efficient at the open circuited end of a transmission line.

For the protection of power station buildings against direct strokes the requirements are

The line insulation is the insulation level of the station equipment.

The interaction between a transmission line and communication line is minimized by

When a wave propagates on a transmission line, it suffers reflection several times at

Which of the following statements is incorrect?

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

Induction cup relay is operated due to changes in

A.C. network analyser is used to solve problems of

Which of the following statements is incorrect ?

Short-circuit currents are due to

To reduce short circuit fault currents are used.

Bus coupler is very essential in arrangement

For cost and safety, the outdoor substations are installed for voltages above

The short circuit in any winding of the transformer is the result of

relays are used for phase faults on long line.

For which of the following protection from negative sequence currents is provided ?

relay is preferred for phase fault on short transmission line.

Distance relays are generally

For which of the following ratings of the transformer differential protection is recommended ?

A _______ is used to measure the stator % winding temperature of the generator.

The under voltage relay can be used for

The relay with inverse time characteristic will operate within

The single phasing relays are used for the protection of

Which of the following devices will receive voltage surge first travelling on the transmission line ?

Which of the following parameter can be neglected for a short line ?

Series reactors should have

Which of the following circuit breakers has high reliability and minimum maintenance ?

Arc in a circuit breaker is interrupted at

transmission line has reflection coefficient as one.

What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ?

The inverse definite mean time relays are used for over current and earth fault protection of transformer against

Over voltage protection is recommended for

Air blast circuit breakers for 400 kV power system are designed to operate in

Overfluxing protection is recommended for

Series capacitors are used to

Admittance relay is _______ relay.

The material used for fuse must have

If the fault occurs near the impedance relay, the VII ratio will be

The torque produced in induction type relay (shaded pole structure) is

The steady state stability of the power system can be increased by

The inductive interference between power and communication line can be minimized by

The power loss is an important factor for the design of

A fuse is connected

H.R.C. fuse, as compared to a rewirable fuse, has

The fuse rating is expressed in terms of

The fuse blows off by

On which of the following effects of electric current a fuse operates ?

An isolator is installed

A fuse in a motor circuit provides protection against

Protection by fuses is generally not used beyond

. A fuse is never inserted in

. Oil switches are employed for

. A switchgear is device used for

. The fuse wire, in D.C. circuits, is inserted in

. By which of the following methods major portion of the heat generated in a H.R.C. fuse is dissipated ?

. A short-circuit is identified by

. The information to the circuit breaker under fault conditions is provided by

. To limit short-circuit current in a power system are used.

. A balanced 3-phase system consists of

. In a single bus-bar system there will be complete shut down when