3-5-1 Primary Fusing/Fuse Principles

Question 1

An open-link cutout cannot interrupt large value faults.

Answer 1

True

Question 2

A fuse cutout using an arc confining tube with a de-ionizing fiber liner and a fuse link is an example of the __?__ principle.

Answer 2

Expulsion

Question 3

The size of the fuse link used depends on the __?__.

Answer 3

backup protection

Question 4

The definition of the term fuse-coordination means that only fused disconnects is coordinated.

Answer 4

False

Question 5

The chief aim of fuse-coordination is to provide power to the __?__ when a fault exists on a distribution circuit.

Answer 5

maximum number of customers

Question 6

The amount of current a fuse is able to interrupt is based on its ability to __?__.

Answer 6

extinguish an arc

Question 7

The melting and clearing time of a fuse should coordinate with both upstream and downstream protective devices.

Answer 7

True

Question 8

The heat from an arc inside a fuse chamber acts on a special coating on the inside walls of the chamber.

Answer 8

True

Question 9

An ordinary expulsion fuse will limit the duration of an arc but not the __?__.

Answer 9

magnitude

Question 10

A current-limiting fuse used on a transformer will reduce the risk of the transformer __?__.

Answer 10

failing explosively

Question 11

The current-limiting fuse which is not used in series with another fuse is the __?__ or general-purpose fuse.

Answer 11

full-range

Question 12

An under-oil expulsion fuse is also called a(n) __?__ fuse.

Answer 12

bayonet style

Question 13

There are __?__ types of under-oil type fuses in this lesson.

Answer 13

2

Question 14

The __?__ type fuse has the fastest clearing time.

Answer 14

K

Question 15

An NX current-limiting fuse is of the __?__ type.

Answer 15

non-expulsion

Question 16

There are __?__ types of fuses commonly used in electrical utility work.

Answer 16

5

Question 17

Per NEMA, a 75-ampere fuse would require a __?__ -inch size fuse holder.

Answer 17

7/17

Question 18

The two most common types of fuses used in overhead distribution are the universal fuse link and the __?__ fuse.

Answer 18

open-link

Question 19

Fuses were used as early as __?__ to protect telegraph cables.

Answer 19

1864

Question 20

Fuse links should not be overstressed by pulling on them when installing them in cutout doors because you may exceed the __?__ pull the manufacturer allows.

Answer 20

10-pound

Question 21

The open-link fuse is the most commonly used fuse in electrical distribution construction.

Answer 21

False

Question 22

A seven-ampere fuse will blow at 14 A of current in __?__ minutes.

Answer 22

5

Question 23

All fuses must meet the ANSI-C__?__ standard.

Answer 23

37.42

Question 24

The formula to find the primary current that a transformer will draw is __?__.

Answer 24

I = P / E

Question 25

A(n) __?__fuse would normally be used to protect a 50-kilovolt-ampere transformer connected to a 14.4-kilvolt line. (round up to nearest whole number)

Answer 25

7-ampere

Question 26

When two transformers are connected open-delta on a delta primary, all cutouts are fused with the same size fuse.

Answer 26

False