108, A 480 volt switchgear breaker feeding an M is tripped. Production has reque
ID: 1765995 • Letter: 1
Question
108, A 480 volt switchgear breaker feeding an M is tripped. Production has requested that power be restored. Arrange the following steps in proper sequence to restore power 1. Isolate the faulty circuit. 2. Test all involved branch circuits. 3. Re-close MCC feeder breaker. 4. Open all MCC branch circuit breakers. 5. Note existing state of all circuit breakers. 6. Test feeder and bus bars for MCC. A. 6, 5, 2,4, 1,3 B. 5, 4, 6, 2, 1,3 C. 2, 1,4, 5, 6,3 D. 6,5, 4,2, 1,3 109. "Single-phasing" normally occurs on a motor when A. an overload trips B. a fuse blows. C. a capacitor burns out D. two wires are reversed 110. A PID temperature controller is set up with too much gain. What will be the result? A. The temperature readout will be inaccurate B. The temperature readout will be too high C. The temperature readout will be too low D. The temperature readout will fail to stabilize DC generators, as a prime source of DC power, are being replaced by A. batteries. B. rectifying units. C. transformers D. power transmitters. 111.Explanation / Answer
108) B.
The sequence followed is 5,4,6,2,1,3.
109) B.
The term single phasing means one of the three phases is open. In regard to a moyor this is worst kind of unbalance a motor can experience. Even though the motor continue to run and try to deliver the full load torque it's not desirable to extend it's operation when single phasing occurs.
110) D.
Too much gain of a control system invites oscillation and might make the system unstable. This same appliea to PID controller as well.
111) B.
Rectifiers are slowly replacing DC generators as prime source of dc power even though the o/p from the rectifier is not that good what we could obtain from DC generators, because dc generators contains a rotating commutator which requires frequent maintenance and/or replacement of parts and hence we are shifting to soild state rectifiers.
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