NCEES (Power) #113

[ndekens]

I have been looking at this problem for a bit and still dont quite understand why they selected the answer A for the neutral current. The supply contains a full-wave rectifier bridge and it would make since that the current graph would look like choice B.

I believe that choice B would be a correct one had they indicated that they where looking at the neutral current between the return diode and the Load and filter cap. Is this a correct statement?

 

[Flyer_PE]

^The supply source is AC and they are looking for current on the line side of the rectifier. As the line swings "negative" the current will be reversed for that half of the cycle. I think selection B would be representative of the current on the load side of the diodes.

I doubt I'm describing it very well but hope this helps.

 

[ndekens]

^The supply source is AC and they are looking for current on the line side of the rectifier. As the line swings "negative" the current will be reversed for that half of the cycle. I think selection B would be representative of the current on the load side of the diodes.
I doubt I'm describing it very well but hope this helps.

Nope you did good. Thats what I was trying to ask. No my next question is why do these NCEES guys have to be so sneaky in how they word there questions and make you just jump to assuming they want a Full wave bridge rectifier wave form from the load side?

 

[Flyer_PE]

^For me, that was the biggest value in the NCEES supplied sample questions. Getting used to the way the questions are presented was a big piece of the puzzle for me.

 

[gEEk2007]

This question stumped me for a while too. Most questions involving a full-wave bridge rectifier that I’ve seen are asking about the output Voltage. Therefore, my first instinct was B.

Thanks!