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Term 1: Electrical Cont'd > Powerpoint - Circuit Protection > Flashcards

Powerpoint - Circuit Protection Flashcards

1
Q

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

A

fuse

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2
Q

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

A

conductors

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3
Q

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

A

temperature

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4
Q

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

A

two

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5
Q

Overcurrent protection:

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

overloads

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6
Q

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

A

short

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7
Q

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

A

overload

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8
Q

Overload protection devices must respond rather ______

A

slow

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9
Q

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

A

series

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10
Q

Name two forms of overcurrent protection

A

fuses, circuit breakers

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11
Q

higher voltage means a _______ fuse

A

longer

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12
Q

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

A

continuous

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13
Q

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

A

short

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14
Q

Plug fuse colour coding

Blue __A
Pink __A
Red__A
Green __A

A

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

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15
Q

Ferrule type cartridge fuses are used up to ___AMps

A

60 amps

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16
Q

Knife type fuses are used from 60A- ____A

A

60-600

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17
Q

Standard code fuses have an interrupting capacity of _______amps

A

10,000amps

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18
Q

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

A

100,00 amps

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19
Q

Two forms of HRC fuses:

Form 1: provides both short circuit and ________ protection

Form 2: provides for short circuit protection _____

A

form 1: overload

form 2: only

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20
Q

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

A

circuit breaker

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21
Q

CEC also requires circuit breakers be ___ free

A

trip

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22
Q

Name three types of circuit breakers:

A

thermal

magnetic

thermal magnetic

solid state

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23
Q

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

A

series

24
Q

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

A

circuits

25
Q

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

A

short circuits and overloads

26
Q

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

A

device

27
Q

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

A

20A

28
Q

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

A

contacts

29
Q

Motor starters have built in means of ________ protection

A

overload

30
Q

Contactors and motor starts can control inductive and ________ loads

A

resistive

31
Q

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

A

125%

32
Q

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

A

protected

33
Q

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

A

protected

34
Q

Motor starter contacts are normally made of ______ or cadmium

A

silver

35
Q

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

A

thermal - magnetic

36
Q

Overloads respond _______

A

slowly

37
Q

standard code fuse interrupting capacity is _________Amps

A

10,000amps

38
Q

High rupturing capacity fuse is ________ amps

A

100,000amps

39
Q

Form 1 HRC provides for both _______ and short circuit protection

A

overload

40
Q

Form 2 HRC provides for ___________ only

A

short circuits only

41
Q

Standard plug fuse colours and ratings?

A

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

42
Q

plug fuse max volt rating?

A

150v to ground

43
Q

Thermal breakers are for ________ only as they are slow response

A

overloads

44
Q

Magnetic breakers protect against _________ only

A

short circuits

45
Q

Thermal-Magnetic breakers protect against _______ and ________

A

overloads and short circuits

46
Q

Are HRC fuses available in plug type

A

No

47
Q

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

A

overload

48
Q

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

A

short circuit

49
Q

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

A

voltage

50
Q

Standard code fuses have a _______ interrupting capacity than HRC fuses

A

lower

51
Q

HRC stands for?

A

high interrupting capacity

52
Q

Time delay fuses marked with “__” and Non-time delay marked with “__”

A

D

P

53
Q

Time delay fuses allow for temporary _______

A

overloads

54
Q

Ferrule type fuses rated for up to ___amps

A

60 amps

55
Q

Knife type fuses rated for 60-____amps

A

60-600amps

Term 1: Electrical Cont'd (7 decks)

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