sequence impedance of transformer
sequence impedance of transformer
(OP)
I want to get data of zero and positive sequence impedance of distribution transformer sized 2,000 and 400 kVA (33,000/400-230 V).Where does I can get these datas?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
Download nowINTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
sequence impedance of transformer
|
RE: sequence impedance of transformer
The Basic Insulation Level (BIL) is the dominant factor to estimate the impedance of the transformer. Thus for 33 K primary voltage the closest rating nominal voltage is 34.5 kV and the std BIL= 200 KV per Table 4 ANSI/IEEE Std C57.12.00.
From Table 7, ANSI/IEEE Std C57.12.10.(% Impedance Voltage) for HV BIL= 200 kV & LV = 480V-->Zt=7.25%.
(+) & (-)Impedance Z1 = Z2 = Zt = 0.0725 pu
(o) Seq. Impedance, Zo = 3.Z1 = 0.2175 pu
RE: sequence impedance of transformer
If the secondary is solidly grounded, the zero-sequence impedance equals the positive-sequence impedance (nameplate impedance). If the secondary is impedance grounded, add 3 times the neutral impedance.
Note that the zero-sequence equivalent circuit has an open in the high (delta) side and a short on the source side of the impedance. That is, the zero-seq impedance is infinite when seen from the delta side and equal to the transformer impedance (without any source impedance) when seen from the wye side.
RE: sequence impedance of transformer
Impedances will vary according to the transformer winding connections.
See References:
1. Electrical Transmission and Distribution Reference Book, Westinghouse Electric Corp., e.g. 1964, Table 5 in the rear.
2. IEEE Std 241-1990 Table 34 indicates transformer design impedance of Z=6% for a transformer of your size and voltages.
Based on the above postings and References, impedances will be:
Z1=Z2=Z=6%
Z0=6% depending on the transfomer connection and grounding.