Anyone know the basic requirements of a test set for detecting shorted turns
in an inductor?

TIA.

ian field wrote:
Anyone know the basic requirements of a test set for detecting shorted turns
in an inductor?

TIA.



Measure the inductance. Shorted turns will lower it.

Ed

ian field wrote:

Anyone know the basic requirements of a test set for detecting shorted turns
in an inductor?


It depends on the inductor. Flyback transformers are "Ring tested" by
hitting it with a pulse, and counting the number of times it rings, at
the signal decays. As Ed said, you can measure the inductance, but a
single shorted turn on a coil with a high turn count will be hard to
determine that way.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"ehsjr" wrote in message
news:jjZ4i.7782$hw.5337@trndny08...
ian field wrote:
Anyone know the basic requirements of a test set for detecting shorted
turns in an inductor?

TIA.

Measure the inductance. Shorted turns will lower it.

Ed

I'm guessing that would only work if you know what the inductance should be
in the first place.

"Michael A. Terrell" wrote in message
...
ian field wrote:

Anyone know the basic requirements of a test set for detecting shorted
turns
in an inductor?


It depends on the inductor. Flyback transformers are "Ring tested" by
hitting it with a pulse, and counting the number of times it rings, at
the signal decays. As Ed said, you can measure the inductance, but a
single shorted turn on a coil with a high turn count will be hard to
determine that way.

It had occurred to me that an inductor with shorted turns would have a much
smaller difference between resistance and inductance, but that's probably
the difficult way of going about it.

Counting the ringing pulses doesn't sound much simpler - how about gauging
flyback energy directly?

On Wed, 23 May 2007 14:43:09 GMT, "ian field"
wrote:

Anyone know the basic requirements of a test set for detecting shorted turns
in an inductor?

TIA.

One method is to apply an AC magnetic field and look for the effect of
current in a shorted turn. This is standard in motor testing, search
on growler shorted turn tester for examples. In the case of a torroid
inductor you might be able to insert a test winding and compare
current at a given excitation voltage & freq; the inductor with the
shorted winding will draw more current.

ian field wrote:

"Michael A. Terrell" wrote in message
...
ian field wrote:

Anyone know the basic requirements of a test set for detecting shorted
turns
in an inductor?


It depends on the inductor. Flyback transformers are "Ring tested" by
hitting it with a pulse, and counting the number of times it rings, at
the signal decays. As Ed said, you can measure the inductance, but a
single shorted turn on a coil with a high turn count will be hard to
determine that way.

It had occurred to me that an inductor with shorted turns would have a much
smaller difference between resistance and inductance, but that's probably
the difficult way of going about it.

Counting the ringing pulses doesn't sound much simpler - how about gauging
flyback energy directly?


There have been a number of flyback testers designed and published, as
well as some kits.
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GWYA,GWYA:2006-31,GWYA:en&q=flyback+ring+test

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"Michael A. Terrell" wrote in message
...
ian field wrote:

"Michael A. Terrell" wrote in message
...
ian field wrote:

Anyone know the basic requirements of a test set for detecting shorted
turns
in an inductor?


It depends on the inductor. Flyback transformers are "Ring tested" by
hitting it with a pulse, and counting the number of times it rings, at
the signal decays. As Ed said, you can measure the inductance, but a
single shorted turn on a coil with a high turn count will be hard to
determine that way.

It had occurred to me that an inductor with shorted turns would have a
much
smaller difference between resistance and inductance, but that's probably
the difficult way of going about it.

Counting the ringing pulses doesn't sound much simpler - how about
gauging
flyback energy directly?


There have been a number of flyback testers designed and published, as
well as some kits.
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GWYA,GWYA:2006-31,GWYA:en&q=flyback+ring+test

Thanks - that turned up the DSE LOPT meter (instructions & schematic), which
is more than my attempt at googling did!

On Wed, 23 May 2007 16:30:09 +0000, ian field wrote:
"ehsjr" wrote in message
news:jjZ4i.7782$hw.5337@trndny08...
ian field wrote:
Anyone know the basic requirements of a test set for detecting shorted
turns in an inductor?

TIA.

Measure the inductance. Shorted turns will lower it.

Ed

I'm guessing that would only work if you know what the inductance should be
in the first place.

Make a parallel-resonant circuit and drive it with a signal at the
resonant frequency. If it gets very, very hot, it has a shorted turn.

Good Luck!
Rich

"ian field" wrote in message
...
Anyone know the basic requirements of a test set for detecting shorted
turns
in an inductor?

TIA.


Attached couple of pics are from a 1951 circuit collection book. Both
circuits rely on the shorted turn(s) sucking power from an external field.
2nd pic looks easy enough to knock together.





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Posted via a free Usenet account from http://www.teranews.com

"ian field" wrote in message
...

Anyone know the basic requirements of a test set for detecting shorted
turns in an inductor?

It varies with the inductor. A 10 uH coil is very different from a 500 VA 50
Hz transformer.

"Homer J Simpson" wrote in message
news:Rz55i.44418$g63.9088@edtnps82...

"ian field" wrote in message
...

Anyone know the basic requirements of a test set for detecting shorted
turns in an inductor?

It varies with the inductor. A 10 uH coil is very different from a 500 VA
50 Hz transformer.




With a 50Hz transformer I can usually plug it in and see how much smoke
escapes - my interest is mainly in line scan & SMPSU type frequencies.