transfromer testing

Also, a transformer's voltage capability decreases nearly proportionately with frequency as frequency is decreased. Longer period of each half-cycle means more core magnetization and (very likely) more core saturation.

By any chance is this transformer rated for 46 Hz? If it is no smaller nor lighter than usual for 50 Hz ones of same volt-amps, then it is probably rated for 46 Hz and not 460. In that case, it is OK at 50 and 60 Hz. Frequencies moderately higher than rated are OK for transformers designed for power line frequencies, with the exception of ones with capacitors for "ferroresonant" voltage regulation in which case only the exact rated frequency should be applied.

- Don Klipstein ( snipped-for-privacy@misty.com)

Might not be a good idea.

To add to that, That sounds like an old military transformer found in various pieces of equipment where the cycle was above 400 Hz or more, I can't remember the exact number.

There are military and aviation 400 Hz transformers. They are smaller than 50 and 60 Hz ones of same volt-amps. But 460?

- Don Klipstein ( snipped-for-privacy@misty.com)

I think aircraft use that sort of frequency. Might be wrong though.

Hello, and attempting to clarify what the above poster said, operating a power transformer designed for ~400 Hz at 60 Hz will probably result in excess excitation current (and subsequent overheating) in the primary winding. This occurs because the inductive reactance of the primary (and secondary) will be considerably less at 60 Hz than at 400 Hz. You might be able to offset this by reducing the primary voltage but then the secondary voltage would be reduced by that same amount.

For a given inductance (L), inductive reactance (2 * pi * freq * L) is directly proportional to the operating frequency. In an aircraft size and weight must be taken into account and a power transformer designed for 400 Hz will meet these criteria more readily than one at 60 Hz at the same power rating. A 400 Hz transformer requires less core material to achieve the minimum required magnetization (excitation) current. Sincerely,

John Wood (Code 5550) e-mail: snipped-for-privacy@itd.nrl.navy.mil Naval Research Laboratory

sir,

thank u for ur advace.

for testing only shall i give 50HZ frequency 226vac prim

or otherwise shall i use funcation generator for testing whether the tarnsformer is good or not.