Deck 2: Fuses, Disconnect Switches, and Circuit Breakers

Question 1

By programming a motor-protective relay unit with the motor's electrical characteristics, the unit's algorithm will automatically tailor the optimal protection curve to the motor being monitored.

Answer 1

True

Question 2

The 120 VAC circuit is normally protected by a single fuse or circuit breaker.

Answer 2

True

Question 3

Switching voltage surges are usually limited to three times normal voltage.

Answer 3

True

Question 4

____ is the current-limiting characteristic of a transformer and is expressed as a percent.

A) Capacitance
B) Impedance
C) Ampacity
D) Rectification

Question 5

The main purpose of a ground fault circuit interrupter (GFCI) is to ____.

A) determine the interrupting capacity
B) calculate the available current
C) protect a person from electrical shock
D) gauge the ambient temperature

Question 6

____________________ fuses are used today in almost all fuse applications.

Question 7

Peak let-thru current (Ip) and ampere squared seconds (I2t) are two measures for the degree of ____ provided by a fuse.

A) current limitation
B) time delay
C) circuit isolation
D) rectification

Question 8

The typical fuse consists of an element surrounded by a filler and enclosed by the fuse body. The element is a calibrated ____.

A) insulator
B) transistor
C) conductor
D) capacitor

Question 9

All protective devices have a published ____________________, which is defined as the highest current at rated voltage that a device can safely interrupt.

Question 10

Adding a(n) ____________________ to the nonautomatic circuit breaker, by using a bimetallic element in each pole of the breaker, provides automatic tripping.