Transformer impedance

[HienN]

Dear all,

To calculate short-cisruit current, we collected transformer impedance from Power company. But the one we got was from 3-winding tranformer (110kV/35kV/22kV) so it was availabe with 3 impedance voltages (P_S side/ P_T side/ and S-T side). Power is supplied to 110kV and derived from 22kV (we will use this voltage). As consulted, I should select the impedance voltage from P_T side but I am still in dout.

Could you shed a light on this case.

Regards,

Hien

 

[davidbeach]

Check out the Blackburn books mentioned in faq238-1287. Excellent references that anybody doing this type of work should have. The Conrad St. Pierre book would also be a good reference.

 

[ijl]

If the tertiary is not connected, then there is only the P_S impedance left. If it is connected, you must use all of them.

 

[waross]

The tertiary winding is not always the lowest voltage. Be sure you are not using P-T when you should be using P-S.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[HienN]

Thank you for your support. P-S side has been using. Thing is I do not know how to unity all of the impedance into one valuable.

I confirmed two Electrical Vendor. They said I should use P-T side's impedance voltage. They did not mention if the P-S side in use or not. So, I still in dout about their information.

Have you ever dealed with this? Please give me your advice.

Regards

Hien