Transformer impedance
Transformer impedance
(OP)
Is there any way to change transformer % impedance by some external means? (Like by putting some external impedance in circuit)
If not then why?
If not then why?
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RE: Transformer impedance
Regards
Marmite
RE: Transformer impedance
The poor man's version is to calculate the cable impedance and use enough length of cable to reduce the ASCC at the switchgear.
I have worked to specs that had wording such as:
The minimum length of cable used to feed unit subs shall be 100 feet. Excess cable shall be doubled back in the cable tray.
Does this solve your issue?
To split hairs, the PU impedance of a transformer may be changed by changing the KVA base. The actual impedance doesn't change so if the KVA base is changed, the PU value changes.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Transformer impedance
RE: Transformer impedance
RE: Transformer impedance
My intention was to ask the manufacturer some sort of arrangement (like tapping some part of winding and the bring it out of body as some contacts where we can add some Independence by some means that can change the %Z value. May be I am thinking a aloud but my aim was to device a method where engineers can play with %Z at site/ substations and there is no need to go back to manufacturer for any future alterations.
Thanks,
ITE
RE: Transformer impedance
Air core reactors are often used to reduce the available fault current to a switchgear lineup.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Transformer impedance
What Marmite said was correct, to the point and adequate.
Rafiq Bulsara
http://www.srengineersct.com
RE: Transformer impedance
Your point is well taken, Rafiq, we weren't playing and this is not something to play with. Design it, install it, and forget it.
Bill
--------------------
"Why not the best?"
Jimmy Carter