Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Electrical Year 2 > Overcurrent Protection > Flashcards

Overcurrent Protection Flashcards

0
Q

What are the problems created by overload.

A

Annealing
Rapid oxidation
Burning insulation
Cracking insulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What is overload?

A

Overload is a moderate increase in current beyond the normal rated current value.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are typical causes for overload?

A

Too much equipment
Use of improper size equipment
A worn out or seized motor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is overcurrent?

A

Ranges from six times to several hundred times the normal rated current.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some causes for overcurrent??

A

Motor start

Short circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are two causes of a short circuit?

A

Failure of the conductors insulation.

A foreign object makes accidental contact causing line to line short.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a short circuit?

A

A larger than normal current that flows outside the normal current path.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a ground fault?

A

Another form of short circuit. Short circuit to ground.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the effects of short circuit current??

A

Mechanical forces

Thermal energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Voltage rating refers to the ability of the protective device to

A

Quickly extinguish the arc

Prevent the open circuit voltage from restriking across the open fuse element

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Current rating

A

The current the device can carry continuously without opening, deteriorating, or exceeding temp limits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Interrupting rating

A

The maximum short circuit current an overcurrent device can safely interrupt without damaging itself.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

A fuse may occasionally open when

A

The ambient temp is high, or excessive vibration.

When the connection is loose or dirty.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When replacing a fuse observe the correct:

A

Voltage rating
Current rating
Interrupting capacity rating
Time current characteristic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Standard voltage ratings of low voltage fuses

A

600V
300V
250V
125V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the interrupting rating on a HRC fuse.

A

200 000 A

16
Q

What types of fuses are there

A

Plug fuses

Cartridge fuses

17
Q

Type W plug fuse

A

Standard non time delay

18
Q

Type D plug fuse

A

Time delay

19
Q

What is the maximum rating for plug fuses

A

30A

125V

20
Q

HRC1 fuse

A

Provides protection from overload and overcurrent

21
Q

HRC11 fuse

A

Short circuit protection only

22
Q

What are the four main types of moulded case circuit breakers

A

Thermal
Thermal-magnetic
Magnetic
Solid state

23
Q

What kind of protection does a magnetic only circuit breaker provide?

A

Short circuit only

24
Q

Five major components of a circuit breaker.

A 
Frame
Operating mechanism 
Trip elements
Contacts
Terminal connection
25
Q

What is trip free

A

It trips even when it’s handle is held in the on position.

Electrical Year 2 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions