Powerpoint - Circuit Protection

Question 1

A _____ is designed to be the weakest link in an electrical circuit

Answer 1

fuse

Question 2

Fuses contain a metal strip of alloy that melts before the ________ do

Answer 2

conductors

Question 3

Dual element fuses (time delay) operates with a built in time delay to allow for ________ overloads such as motor starting

Answer 3

temperature

Question 4

Dual element fuses have _____ fuse elements, one for overloads and one for short circuits

Answer 4

two

Question 5

Overcurrent protection:

• a current that exceeds some predetermined value that includes short circuits and ________

Answer 5

overloads

Question 6

A _____ circuit is a current larger than normal which flows outside its normal path

Answer 6

short

Question 7

An _______ is a current larger than normal but still flows within its normal path, normal range, within 3-6 times the FLA

Answer 7

overload

Question 8

Overload protection devices must respond rather ______

Answer 8

slow

Question 9

Overcurrent and overload devices must be wired in ______ with the cat being protected

Answer 9

series

Question 10

Name two forms of overcurrent protection

Answer 10

fuses, circuit breakers

Question 11

higher voltage means a _______ fuse

Answer 11

longer

Question 12

__________ current rating is the maximum amount of current the fuse is designed to carry for long periods of time

Answer 12

continuous

Question 13

Interrupting capacity is the max ______ circuit current an overcurrent device can safely interrupt

Answer 13

short

Question 14

Plug fuse colour coding

Blue __A
Pink __A
Red__A
Green __A

Answer 14

Blue - 15A
Pink - 20A
Red - 25A
Green - 30A

Question 15

Ferrule type cartridge fuses are used up to ___AMps

Answer 15

60 amps

Question 16

Knife type fuses are used from 60A- ____A

Answer 16

60-600

Question 17

Standard code fuses have an interrupting capacity of _______amps

Answer 17

10,000amps

Question 18

High rupturing capacity fuses (HRC) have an interrupting capacity of _________

Answer 18

100,00 amps

Question 19

Two forms of HRC fuses:

Form 1: provides both short circuit and ________ protection

Form 2: provides for short circuit protection _____

Answer 19

form 1: overload

form 2: only

Question 20

The CEC defines a _________ as an electromechanical device designed to open a current carrying circuit under both overload and short cct conditions

Answer 20

circuit breaker

Question 21

CEC also requires circuit breakers be ___ free

Answer 21

trip

Question 22

Name three types of circuit breakers:

Answer 22

thermal

magnetic

thermal magnetic

solid state

Question 23

thermal circuit breakers are connected in ______ with the load it controls and its function is to protect the circuit against overloads

Answer 23

series

Question 24

Magnetic breakers have a magnetic connected in series with contacts and it protects against short _____

Answer 24

circuits

Question 25

The thermal magnetic breaker has a thermal element and electromagnetic in series with the contacts, it protects against both _______ and _________

Answer 25

short circuits and overloads

Question 26

GFCI detect a difference between the current flowing in the conductor to the load, and the current returning to the ______

Answer 26

device

Question 27

Relays are normally used to carry less than ___A of rated current flow through the contacts

Answer 27

20A

Question 28

Contactors are larger versions of a relay and normally carries between 20-60a through the _______

Answer 28

contacts

Question 29

Motor starters have built in means of ________ protection

Answer 29

overload

Question 30

Contactors and motor starts can control inductive and ________ loads

Answer 30

resistive

Question 31

Overload protection in a motor starter is rated at not more than ____% of the motor RLA

Answer 31

125%

Question 32

(motor starter) For over current protection with fuses on single phase or three phase it is required that all hot legs be ________

Answer 32

protected

Question 33

(motor starter) For overload protection only the two hot legs must be ______

Answer 33

protected

Question 34

Motor starter contacts are normally made of ______ or cadmium

Answer 34

silver

Question 35

Overload protection on motor starters may be magnetic, thermal or ______-________

Answer 35

thermal - magnetic

Question 36

Overloads respond _______

Answer 36

slowly

Question 37

standard code fuse interrupting capacity is _________Amps

Answer 37

10,000amps

Question 38

High rupturing capacity fuse is ________ amps

Answer 38

100,000amps

Question 39

Form 1 HRC provides for both _______ and short circuit protection

Answer 39

overload

Question 40

Form 2 HRC provides for ___________ only

Answer 40

short circuits only

Question 41

Standard plug fuse colours and ratings?

Answer 41

B - 15a P - 20a R - 25a G - 30a

Question 42

plug fuse max volt rating?

Answer 42

150v to ground

Question 43

Thermal breakers are for ________ only as they are slow response

Answer 43

overloads

Question 44

Magnetic breakers protect against _________ only

Answer 44

short circuits

Question 45

Thermal-Magnetic breakers protect against _______ and ________

Answer 45

overloads and short circuits

Question 46

Are HRC fuses available in plug type

Answer 46

No

Question 47

A current larger than normal, but flowing within its normal current path is referred to as an __________

Answer 47

overload

Question 48

A current larger than normal but flowing outside its normal current path is referred to as a ________

Answer 48

short circuit

Question 49

The ________ rating refers to the ability of a fuse/breaker to extinguish an arc after opening

Answer 49

voltage

Question 50

Standard code fuses have a _______ interrupting capacity than HRC fuses

Answer 50

lower

Question 51

HRC stands for?

Answer 51

high interrupting capacity

Question 52

Time delay fuses marked with "__" and Non-time delay marked with "__"

Answer 52

D P

Question 53

Time delay fuses allow for temporary _______

Answer 53

overloads

Question 54

Ferrule type fuses rated for up to ___amps

Answer 54

60 amps

Question 55

Knife type fuses rated for 60-____amps

Answer 55

60-600amps