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transfromer testing

D

Don Klipstein

Jan 1, 1970
0
In <[email protected]>,
hai,

i have 220vac/75vac 460hz transfromer

shall i test it with 230vac 50hz supply

460 Hz? Very oddball frequency! Where did it come from, and what is
this transformer for?

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 ([email protected])
 
J

Jamie

Jan 1, 1970
0
Jamie said:
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.
 
D

Don Klipstein

Jan 1, 1970
0
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 ([email protected])
 
J

J. B. Wood

Jan 1, 1970
0
"Charles" said:
If it is indeed a 460 Hz device, you can only use it safely at a greatly
reduced primary voltage at 60 Hz.

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: [email protected]
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337
 
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: [email protected]
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-533
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.
 
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