Reply to thread

Professional Engineer & PE Exam Forum

Help Support Professional Engineer & PE Exam Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

I'm strugguling to understand why the current in this problem is I = 1pu.  The problem is as follows:


An electric generator is rated for 20MVA, 13.8KV.  It is a diesel engine driven, three phase, four-wire system.  The generator is sailent pole with dampers.  The manufacturer's data for reactances is:


X"d = 0.20,      X'd = 0.30,      Xd = 1.25,    Xq = 0.90


Assume a terminal voltage of 1pu for a transient study conducted at rated power and voltage.  The power factor is 1.0.  What magnitude of generated voltage should be used for this study?


I know the following:


E'm = Vt - iX'dm, where E'm = generated transient voltage


Vt = 1pu    Xdm = 0.3     These where stated in the problem.


Not really sure why I = 1pu.  I guess it must have come from Vt being 1pu and the study being conducted at rated voltage and power.


Some explanation behind this would be appreciated.


Thanks in advance


Back
Top