Paul,

Mine is not a standard test but see if it helps in your
case. We use impedence analyser or certain LCR bridge (e.g.
HP4284A) to measure the phase angle. In the AC phasor
diagram, the DCR vector is at 0 deg, the XL vector is at
90deg, the XC vector is at -90deg. If the DCR is small, an
inductive coil should have the phase angle close to 90deg.
With the intra-winding capacitance, the angle will be
dragged down. This simple principle may help you to
calculate the exact capacitance.

K.K. Chin
Artesyn Technologies
www.artesyn.com



From: Paul Orlando <[log in to unmask]> AT NetMail on
      08/18/98 11:30 AM EDT

To:   [log in to unmask] AT NetMail@ccmail2
cc:    (bcc: KK Chin)
Subject:  [TN] Testing of transformer coils





Hello Techies,

This may be a little off topic but here goes:

I'm looking for a standard (IEEE preferred, but anything
would be fine) for high voltage, high current testing or
more properly, characterizing, of a transformer like coil. A
high voltage pulse would be applied to an inductive device
under test. The inductor would have a test capacitance
across it and after the pulse was applied, the ring down
current and voltage would be monitored as a signature
profile is looked for. The purpose is to look for turn to
turn shorts which appear only under high voltage operating
conditions. Standard HiPot tests don't apply since we are
looking for turn to turn faults which. Simple resistance
tests don't apply either since the fault only appears under
high current conditions. We are trying to develop a test
whithout requireing our vendor to purchase high current
continuos wave amplifiers.



Thanks in advance,

Paul Orlando
[log in to unmask]

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