15
Figure 2-D.—Power distribution system using
selective tripping.
IN ANSWERING QUESTIONS 2-60
THROUGH 2-62, REFER TO FIGURE 2-D.
2-60. Which of the following circuit breakers
should have a long time delay?
1. CB1
2. CB2
3. CB3
4. CB4
2-61. Which of the following circuit breakers
should have a short time delay?
1. CB1
2. CB2
3. CB5
4. CB4
2-62. Which of the following circuit breakers
should have an instantaneous time delay?
1. CB1
2. CB2
3. CB3
4. CB4
2-63. The following actions must be taken
prior to working on a circuit breaker.
Arrange these items in the proper
sequence, then select the choice below
that lists the events in the proper
sequence.
A. Tag the power switch
B. Obtain the approval of the
electrical officer
C. Remove power to the circuit
breaker
D. Check the applicable technical
manual
1. A, B, C, D
2. C, B, D, A
3. D, B, C, A
4. B, A, D, C
2-64. Which of the following items is NOT
checked during maintenance on a circuit
breaker?
1. Input power voltage
2. Operating mechanism smoothness
3. Terminal tightness and corrosion
4. Contact surfaces for pitting
