I have couple of questions, to which I would love to have some clarifications.

i) How do continuous high voltages on a transformer secondary damage them? (Voltages in range of 1.05 pu to 1.15 pu)

ii) The transformer are generally rated to 1.05 pu at full load, .80 pf and 1.10 at no load. What is the acceptable voltages for the transformers say at 10% loading and unknown pf?

iii) Is low or high power factor preferable during high voltages but low loading?

 

Amrit...

i) If load varies +)/(-) 10%, then RMS-load calcultaion, involving duration of operation at each level, should be performed!

iia) PF is never given as a Nameplate parameter! Operating at 1.05pu load and 0.8 PF is quite acceptable. But, success depends on load-duration!

iib) Operating at 0.1pu, with an unknown PF should never be considered without Mfg's input!

iii) Specific loading characteristics are preferred! Unknowns, especially if extreme, should be discussed with Mfg!

Regards,
Phil Corso