Exam 13: System Protection

Circuit breakers actually have two different current ratings. One is the trip rating, and the other is the ________rating.

________means that when an overload or fault condition occurs, only the part of the electrical system that is in jeopardy is disconnected.

Coordination among multiple ground-fault protectors is achieved by using a lower________ setting and progressively shorter time settings on each of the downstream devices.

When an electric arc occurs in air, gas molecules in the air ________.

The________ is the point at which a breaker responds to a short-circuit current through a magnetically actuated trip arrangement.

The amount of current that will flow during a short-circuit condition is determined by two factors: the voltage and the ____.

The three major types of circuit breakers are air, oil, and________ .

There are two basic types of oil circuit breakers, the full tank or dead tank type and the low oil or ________type.

What is indicated by the long-time delay portion of the time-current curve?

________air circuit breakers are used in low-voltage (600 volts or less), low-current circuits.

Classify low oil (also called oil poor) circuit breakers.

A ground-fault protective device consists of a ground-fault sensor and a________ .

A system containing only ________is the easiest situation to coordinate.

What is the mechanism behind the operation of a thermal circuit breaker?

What is an auxiliary switch?

________trips are used to open the circuit breaker contacts by energizing the solenoid from an external source.

What are some required and recommended uses for ground-fault protection devices?

In magnetic-type circuit breakers , there is________ time delay in the opening of the contacts when an overload occurs.

Low-voltage power circuit breakers commonly have ________set(s) of contacts.

One method used by circuit breakers to sense circuit current is to connect a(n)________ in series with the load.