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

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

Which one of the following devices is most often used for measuring electrical potential difference?

A

Voltmeter

B

Ohmmeter

C

Ammeter

D

Wattmeter

E

None of the above

Why are digital circuits easier to design than analog circuits?

A

they do not control electricity precisely over a wide range

B

they are made in the form of ICs

C

all elements of digital circuit are from the same family

D

they are smaller in size

E

None of the above

Switches and relays should be shown in this position with no operating force or applied energy:

A

Normal

B

Closed

C

Offset

D

Application

Which of the following relays is used on long transmission lines?

A

Impedance relay

B

Mho's relay

C

Reactance relay

D

None of the above

The phase lag produced by transportation relays

A

Is independent of frequency

B

Is inversely proportional to frequency

C

Increases linearly with frequency

D

Decreases linearly with frequency

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

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

Overload relays are of type.

A

induction

B

solid state

C

thermal

D

electromagnetic

E

all above

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

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

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