Transformer inrush current
Transformer inrush current
(OP)
Dear Friends,
Could anyone please clarify that the transformer inrush current (6 to 12/14 times) normally specified based on Transformer ONAN rating or ONAF rating?
Could anyone please clarify that the transformer inrush current (6 to 12/14 times) normally specified based on Transformer ONAN rating or ONAF rating?






RE: Transformer inrush current
Regards
RE: Transformer inrush current
http://www.qte.com/Main%20Pages/Technical%20Papers%20Page/Inrush%20Page/qte_tech_papers_inrush.htm
for smaller justified current inrushes.
RE: Transformer inrush current
RE: Transformer inrush current
Peak inrush (around 2 cycles) Phase A 1.16 x full load amps, Phase B 2.76 x full load amps, Phase C 2.56 x full load amps.
Phase A inrush dropped to 1.13 x full load in 25 cycles.
Peak differential relay operating current was 1.77 x full load. Peak second harmonic current was 1.07 x full load.
RE: Transformer inrush current
The rating of the transformer, I am referring is 15/22.5 MVA, 13.8/34.5 kV, ONAN/ONAF, Z = 10 % step up transformer.
In absense of the manufacturer's data for magnetising inrush current, I have the following doubt:
The magnetising inrush current should be considered as K times the current rating on ONAN rating i.e (K times 627 Amps) or K times the current rating on ONAF rating i.e (K times 941 Amps)?
Please advise.
RE: Transformer inrush current
2 times full load @ 100 sec
3 times full load @ 10 sec
6 times full load @ 1 sec
12 times full load @ 0.1 sec
25 times full load @ 0.01 sec
RE: Transformer inrush current
Inrush at 25 cycles: Phase A 0.55 x full load, Phase B 1.25 x full load, Phase C 1.13 x full load.
RE: Transformer inrush current
Bung
Life is non-linear...