# power systems

Discussion in 'Homework Help' started by Geney, Jun 30, 2012.

1. ### Geney Thread Starter New Member

Apr 2, 2012
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0
can someone help me out in power system analysis...

2. ### wmodavis Well-Known Member

Oct 23, 2010
737
150
Yeah! Got a SPECIFIC question?

3. ### Geney Thread Starter New Member

Apr 2, 2012
18
0
yes! while analyzing performance of transmission lines... why do we consider the receiving end voltage leading the sending end current (taken as reference)

4. ### WBahn Moderator

Mar 31, 2012
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4,796
The question isn't very clear. The receiving end voltage is either leading the sending end current or it is not, there's no "considering" about it.

Now, if you are asking why we make our measurements based on how much the voltage is leading/lagging the current instead of how much the current is leading/lagging the voltage, that is a matter of convention. Keep in mind that most loads, particularly at the time when these conventions were all being developed, tended to be net inductive loads. So the load impedance usually had a positive phase angle resulting in the voltage leading the current. So that you can work with positive numbers most of the time (reduced the opportunities for stupid math errors), you adopt the convention that this relationship will be described using a positive quantity and the alternative, the current leading the voltage, will be described with a negative quantity.