Grainger problem1.1

[kduff70]

Hi can anyone make sense on what the correct phasor experssion should be for the current and voltage the solution problems was all marked up not sure what the correct answer should be i tend to think the phase shift for the current phase angle is 30 degrees and the voltage is 0 degrees .

Thank you

 

[JB66money]

Kduff,

You may want to add Glover and Sarma as a reference. He has really good information on faults (balanced & unbalanced) and system protection. He also has really good examples for many of the topics that you have been going over in Grainger. In my opinion the Glover and Sarma text is better than Grainger's text. Also add Theodore Wildi's text as well, his text is very good for looking things up because he covers a broad range of topics.

 

[kduff70]

you right I'm just trying to absorb some more problem outside of spin ci ncees and graffeo that I might see some similar on the test so I trying to get as many problem I think might come for Grainger but some step are missing that through me for a curve on a few but thank you

 

[zm83]

Where did you find the Grainger solutions?

 

[kduff70]

here a link but if you google solution for grainger there were alot place to get it

http://www.scribd.com/doc/28613914/Power-Systems-Analysis-Solutions-Manual#scribd

 

[dayrongarcia]

I think the original answer is correct, will need to check my formulas once I get home.

 

[Panchito]

I am not a power engineer, but I think the handwritten answer is the correct one. In the problem, the voltage is given as a COSINE function and the current as a SINE funtion. As you know, a cosine wave leads a sine wave by 90deg. Therefore, when you compare the angle phase shift between these V and I signals, you have to take into account also this -90 deg.

So the phase shift between the voltage and the current (using the voltage angle as reference) is:
ANG(current) - ANG(volt)=
(-30 deg) - (30 deg - 90 deg) = +30 deg

Therefore, the current leads the voltage by +30 deg

 

[kduff70]

i get - 60 deg is you just - 90 deg from the cosine side but it seems like it negelect the minuse 30deg phase shift