3-5-4 Substations - Oil Circuit Breakers

Question 1

Substation circuit breakers are used to interrupt full load currents and fault currents.

Answer 1

True

Question 2

The full load amperes rating of a circuit breaker is the maximum __?__ capacity of the breaker.

Answer 2

current-carrying

Question 3

At a three-phase circuit breaker installation, the bushings at the left are numbered __?__, __?__, and __?__.

Answer 3

1, 3, 5

Question 4

Substation breakers can only be operated by AC.

Answer 4

False

Question 5

There are __?__ systems which can operate a substation breaker’s mechanism.

Answer 5

5

Question 6

A system which can operate a substation breaker’s mechanism uses __?__.

Answer 6

air or other gases

Question 7

A low voltage operation test on a substation circuit breaker is at approximately __?__ of full AC voltage.

Answer 7

75%

Question 8

The __?__ closing device should not be used to open or close a substation circuit breaker when it is carrying load.

Answer 8

manual

Question 9

A circuit breaker which uses air at atmospheric pressure as a quenching medium is normally used on voltages of __?__ .

Answer 9

430-600V

Question 10

If operating properly, substation circuit breakers will open in approximately __?__ cycles.

Answer 10

3 1/2

Question 11

In an OCB, the arc interrupting medium is __?__.

Answer 11

dielectric oil

Question 12

Wear to an OCB’s contacts may happen due to improper timing of the contact movement, worn contact surfaces, and poor contact__?__.

Answer 12

alignment

Question 13

A Dissolved Gas Analysis is performed on a substation circuit breaker to see if there are hydrocarbon gases in the oil.

Answer 13

True

Question 14

When the oil from a substation circuit breaker is filtered, it is checked for __?__.

Answer 14

particle count and size

Question 15

The poles of an OCB should be subjected to a __?__ test.

Answer 15

resistance

Question 16

Acetylene is an example of a(n) __?__ gas which might be found inside an OCB.

Answer 16

hydrocarbon

Question 17

Unless previously checked, the oil from an OCB should be checked for __?__ prior to doing maintenance on a unit that was built prior to 1980.

Answer 17

PCBs

Question 18

On a substation OCB, the trip and closing coil resistance is measured as part of the testing procedure, after the installation has been completed.

Answer 18

True

Question 19

When installed, the right hand bushings of an OCB are numbered __?__, __?__, and __?__.

Answer 19

2, 4, 6

Question 20

Circuit breakers may only be installed outdoors.

Answer 20

False

Question 21

Substation breaker mechanisms cannot be operated pneumatically.

Answer 21

False

Question 22

In An OCB, the arc is extinguished when the AC wave is at current __?__.

Answer 22

zero degrees

Question 23

There are approximately __?__ substations in the United States that use OCBs.

Answer 23

100,000

Question 24

According to this lesson, a high voltage DC circuit breaker uses __?__ as an interrupting medium.

Answer 24

vacuum