Apparatus 2

Question 1

are used in AC system for measurement of
electrical quantities i.e., voltage, current, power, energy, power factor,
frequency

Answer 1

Instrument Transformers

Question 2

is to step down the AC
System voltage and current

Answer 2

Basic function of Instrument transformers

Question 3

is
used to step down the
current of power system
to a lower level to make it
feasible to be measured by
small rating Ammeter (i.e.,
5A ammeter)

Answer 3

CURRENT TRANSFORMER (C.T.)

Question 4

is used
to step down the voltage of
power system to a lower level
to make is feasible to be
measured by small rating
voltmeter i.e., 110 – 120 V
voltmeter

Answer 4

POTENTIAL TRANSFORMER (P.T.)

Question 5

is an absolutely essential device in the modern
world, and one of the most important safety mechanisms in your
home

Answer 5

The circuit breaker

Question 6

These breakers are rated for use at low voltages up to 2 kV and are
mainly used in small-scale industries.

Answer 6

Low voltage circuit breakers

Question 7

These breakers are rated for use at voltages greater than 2 kV. High
voltage circuit breakers are further subdivided into transmission class
breakers.
o Those which are rated 123 kV and above
o Medium voltage class (lesser than 72 kV) circuit breaker

Answer 7

High voltage circuit breakers

Question 8

These are designed to use inside the buildings or in weather-resistant
enclosures. They are typically operated at a medium voltage with a
metal clad switchgear enclosure.

Answer 8

Indoor circuit breakers

Question 9

You can use these breakers outdoors without any roof due to their
design. Their external enclosure arrangement is strong compared to the
indoor breakers and can withstand wear and tear.

Answer 9

Outdoor Circuit breakers

Question 10

The breakers whose enclosed tank is at ground potential are known as
dead tank circuit breakers. Their tank encloses all the insulating and
interrupting medium. In other words, the tank is shorted to ground, or
it is at dead potential.

Answer 10

Dead tank circuit breakers

Question 11

These breakers have a tank housing interrupter that is at a potential
above the ground. It is above the ground with some insulation medium
in between

Answer 11

Live tank circuit breakers

Question 12

This breaker uses air as an insulating and interrupting medium. The
breaker is sub-classified into two types:
oLow voltage circuit breaker whose value lies below 1000 V.
oHigh voltage circuit breaker whose value is 1000 V and above.

Answer 12

Air circuit breaker

Question 13

It uses oil as an interrupting and insulating medium. These breakers are
divided into two types based on the pressure and amount of oil used

Answer 13

Oil circuit breaker

Question 14

These breakers use vacuum as the interrupting medium due to its high
dielectric and diffusive properties

Answer 14

Vacuum circuit breakers

Question 15

The current ratings for this breaker are less than 100A and has only one
over-current protection built within it. The trip settings are not
adjustable in this circuit.

Answer 15

MCB (Miniature Circuit Breaker)

Question 16

Current ratings for these breakers are higher than 1000A. They have
earth fault protection along with current protection. The trip settings of
the Molded Case Circuit Breaker can be adjusted easily.

Answer 16

MCCB (Molded Case Circuit Breakers)

Question 17

This breaker has one hot wire and one neutral wire that operate at 120
V. When there is a fault, it will interrupt just the hot wire.

Answer 17

Single pole circuit breaker

Question 18

This is used for 220 V. There are two hot wires, and both the poles need
to be interrupted.

Answer 18

Double pole circuit breaker

Question 19

These are safety switches that trip on ground fault current. The GFCI
breaker interrupts the electrical circuit when it detects the slightest
variance between phase and neutral wires.

Answer 19

GFI or GFCI circuit breaker (Ground fault circuit interrupter)

Question 20

The AFCI breaker interrupts the circuit during excessive arc conditions
and prevents fire. Under the normal arcing condition, this breaker will
be idle and won’t interrupt the circuit

Answer 20

Arc Fault circuit interrupter (AFCI)

Question 21

is an electrical safety device built around a conductive strip
that is designed to melt and separate in the event of excessive
current.

Answer 21

fuses

Question 22

The device which is used for the protection of the equipment at the
substations against travelling waves.

Answer 22

LIGHTNING ARRESTERS

Question 23

is automatic device which senses an abnormal condition of
electrical circuit and closes its contacts.

Answer 23

PROTECTION RELAYS

Question 24

are used as a
protective device, as they are
sensitive to the effects of dielectric
failure that can occur inside the
equipment they protect.

Answer 24

Buchholz relays