PROTECTION DEVICES (030204d)

Question 1

When a path of extremely low impedance is created in a circuit, there would be a

Answer 1

Short circuit condition

Question 2

A fault current is the current that is caused by

Answer 2

A low impedance path to ground

Question 3

All circuits and electrical systems require protection against an

Answer 3

Overcurrent condition

Question 4

An overload condition can cause the damage to equipment due to

Answer 4

Excessive heat

Question 5

What best describes an overload condition

Answer 5

A motor with an excess mechanical load

Question 6

The continuous rating of an overcurrent device refers to

Answer 6

The current above which the device begins to react

Question 7

The higher the overload current, the _______ the reaction time

Answer 7

Shorter

Question 8

A time-limit type circuit breaker will protect a circuit from

Answer 8

Overloads or short circuits

Question 9

True or false

The interrupting rating of the fuse or circuit breaker is normally in the range of several thousand amperes

Answer 9

True

Question 10

In motor branch circuits, which circuit characteristics are used when calculating the minimum interrupted capacity for fuses

Answer 10

kVA and percent impedance rating of the supply transformer

Question 11

One of the factors that determines the maximum short-circuit current in a branch circuit is the

Answer 11

Voltage of the circuit where the fault occurs

Question 12

The interrupting rating of a circuit protective device applies to all types of _______ _______

Answer 12

Overcurrent devices

Question 13

True or false

The kVA rating and the percent impedance(IZ%) of the supply transformer, both affect the amount of short circuit current that could flow.

Answer 13

True

Question 14

True or false

All ungrounded circuit conductors must be disconnected from the motor by disconnecting means .

Answer 14

True

Question 15

What is the primary purpose of the motor disconnect?

Answer 15

To prove a way of disconnecting the motor from all ungrounded circuit conductors

Question 16

How many purposes does a fused disconnect have?

Answer 16

2

Question 17

Line voltage _____ devices, such as thermostats and floats, which is are connected in _____ with the _____ motor circuit switch to control the motor

Answer 17

Pilot
Series
Manual

Question 18

A thermally responsive overload device is warmed by a heater that is a ____ length of a ____ resistance conductor

Answer 18

Short
Low

Question 19

What is the full load capacity of a motor?

Answer 19

The highest current set by the manufacturer that the motor can carry without damage

Question 20

True or false

Except for motor circuits, circuit breakers can generally provide protection against both overload and overcurrent circuit conditions

Answer 20

True

Question 21

True or false

Most motor branch circuits must have overcurrent protection, overload protection, a controller, and a disconnecting means

Answer 21

True

Question 22

True or false

Correctly sized standard fuse used as the protective device in a motor circuit will give both overload and overcurrent protection

Answer 22

False

Question 23

True or false

The ampere rating of a fuse for a motor circuit would depend upon whether it is a standard or time-delay type of device

Answer 23

True

Question 24

True or false

Fuses and circuit breakers are not to be considered as circuit protective devices

Answer 24

False

Question 25

True or false

Motors WITH built-in thermal protection, must have external overload devices

Answer 25

False

Question 26

A motor with a high service factor can

Answer 26

Stand a longer duration of overload

Question 27

True or false

According to the CEC, motor circuits must provide both overcurrent and overload protection

Answer 27

False

Question 28

True or false

Standard fuses or circuit breakers used in motor circuits provide protection against overloads

Answer 28

False