3-5-4 Substations - Oil Circuit Breakers Flashcards
Substation circuit breakers are used to interrupt full load currents and fault currents.
True
The full load amperes rating of a circuit breaker is the maximum __?__ capacity of the breaker.
current-carrying
At a three-phase circuit breaker installation, the bushings at the left are numbered __?__, __?__, and __?__.
1, 3, 5
Substation breakers can only be operated by AC.
False
There are __?__ systems which can operate a substation breaker’s mechanism.
5
A system which can operate a substation breaker’s mechanism uses __?__.
air or other gases
A low voltage operation test on a substation circuit breaker is at approximately __?__ of full AC voltage.
75%
The __?__ closing device should not be used to open or close a substation circuit breaker when it is carrying load.
manual
A circuit breaker which uses air at atmospheric pressure as a quenching medium is normally used on voltages of __?__ .
430-600V
If operating properly, substation circuit breakers will open in approximately __?__ cycles.
3 1/2
In an OCB, the arc interrupting medium is __?__.
dielectric oil
Wear to an OCB’s contacts may happen due to improper timing of the contact movement, worn contact surfaces, and poor contact__?__.
alignment
A Dissolved Gas Analysis is performed on a substation circuit breaker to see if there are hydrocarbon gases in the oil.
True
When the oil from a substation circuit breaker is filtered, it is checked for __?__.
particle count and size
The poles of an OCB should be subjected to a __?__ test.
resistance
Acetylene is an example of a(n) __?__ gas which might be found inside an OCB.
hydrocarbon
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.
PCBs
On a substation OCB, the trip and closing coil resistance is measured as part of the testing procedure, after the installation has been completed.
True
When installed, the right hand bushings of an OCB are numbered __?__, __?__, and __?__.
2, 4, 6
Circuit breakers may only be installed outdoors.
False
Substation breaker mechanisms cannot be operated pneumatically.
False
In An OCB, the arc is extinguished when the AC wave is at current __?__.
zero degrees
There are approximately __?__ substations in the United States that use OCBs.
100,000
According to this lesson, a high voltage DC circuit breaker uses __?__ as an interrupting medium.
vacuum
