Engineer Boards

# NCEES #519 Power

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Can someone please provide a better explination of this solution? What has been posted thus far isn't getting me there. Thanks.

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Can someone please provide a better explination of this solution? What has been posted thus far isn't getting me there. Thanks.

Kaplan gave a good explanation of rectifiers in Chapter 14. The diodes turn on when voltages are positive. I normal three phase rectifier looks like answer (A). You will see a peak when the current in phase a is positive and either the current in phase B or C is also positive. You will see a negative peak when phase a is negative and either b or c is also negative.

With fuse C blown, you will only see a peak when phase A is positive/negative and phase B is also positive/negative.

Hope that makes since..

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I think the key to this problem is understanding what is asked. The problem asks ONLY for PHASE A. Not for the circuit.

Second part is understanding that PHASE A will (1) have one peak over a cycle, 1/60s, and (2) one negative peak as it will carry the return current from phase B.

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Thanks. Those answers make better sense.

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Thanks. Those answers make better sense.

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I think the key to this problem is understanding what is asked. The problem asks ONLY for PHASE A. Not for the circuit.

Second part is understanding that PHASE A will (1) have one peak over a cycle, 1/60s, and (2) one negative peak as it will carry the return current from phase B.

What part does the capacitor play in the current waveform?

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check out this applet. it helps:

/>http://services.eng.uts.edu.au/~venkat/pe_html/ch05s1/ch05s1p1.htm

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Just as a reality check and going back to being aware of what the question is asking, the ia that they refer to in the question is not the ia that they refer to in the diagram, right?

And Phase A means the Phase A at the motor?