Transformer Impedance

A

Thread Starter

Aj

when impedance is 5% we say loss is 5% of transformer capacity at operating frequency say 50hz . If frequency is 1hz will powerloss be less 50 times.
 
C

Curt Wuollet

Only if you have huge transformer with enough windings and iron to
present a reasonably high open circuit impedance at 1 Hz. Your typical 50 Hz transformer would look a lot like a short at 1 Hz and so would approach it's DC resistance.

So in theory it is proportional, with practical transformers you would have a completely different animal at 1 Hz.

Regards
cww
 
Aj... No! Losses do not decrease as frequency decreases. Instead, they increase!

Have you considered the often used Caveat, "Maintain V/F constant when a transformer is connected to an accelerating, but energized, generator!" The exact caveat is used in the operation of VSDs or VFDs!

Neglecting the practical world where non-linear characteristics are present in all electro-magnet systems, assume V is sinusoidal and its magnitude also constant!

The current, I, is equal to the simple formula (PtPs cover your ears) V/Z. Z has two components; one a resistor R, the other an inductor L. And, Z=SQRT(R^2+X^2) where X=2x(Pi)x(F)x(L).

Note, the X term is proportional to frequency, then, if F decreases, so do X and Z, causing I to increase. Finally, because loss in any electrical apparatus equals I^2xR, transformer losses will increase for decreasing frequency.

PtPs can now uncover their ears!

Regards, Phil Corso
 
Top