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Re: OLTC Measuring Peak Current

Original poster: robert heidlebaugh <rheidlebaugh@xxxxxxxxxxxxxx>

Adam: The simple way to measure peak current is with a shunt. A shunt is not
subject to frequency degridation like transformers. Low current shunts are
relativly inexpencive, but high current shunts are hard to find and you
usualy must make one.  Calibration is not dificult. Start with a low
resistance such as a stainless steel bar. A 1" x 12" piece of sheet metal
works for 100 Amps or less or over 100 amps for short durations. Put a known
current through the shunt of lets say 10 amps then move your amp meter along
the shunt to read 1 amp. Mark this point and rivet and solder a connector to
this point. You now have a 10:1 shunt. Sears sells a small role of pure tin
solder and acid flux in a small blister pack that solders stainless or use
silver solder. To monitor fast time currents connect a scope to your
connection point. NOTE I did not measure the resistance of the shunt. That
requires a calibrated good quality bridge. Few people have one and it is not
nessisary. I have a 1000A shunt made of a piece of stainless round stock.
calibrated to 6 places in a standards lab. You can make it  with what you
have in your shop calibrated to the acuracy of your test equipment.
      Robert   H

> From: "Tesla list" <tesla@xxxxxxxxxx>
> Date: Mon, 03 Jan 2005 17:11:04 -0700
> To: tesla@xxxxxxxxxx
> Subject: OLTC Measuring Peak Current
> Resent-From: tesla@xxxxxxxxxx
> Resent-Date: Mon, 3 Jan 2005 17:20:33 -0700 (MST)
> Original poster: "Adam Horden" <adamhorden@xxxxxxxxxxxx>
> Hi All
> I am currently rebuilding my OLTC. I have rebuilt the controller and
> preliminary test show that it's working in constant BPS mode but the
> interrupted drive needs some work.
> I was wondering how I can go about measuring the peak current. I was
> planning to measure it on one side of the capacitor bank (not the
> neutral side)
> I don't have room in the low inductance layout for my ion physics
> current transformer (its about 6 inch dia).
> I was wondering how I can measure the peak current.
> Maybe a current transformer wound on a 1inch ferrite core?
> Adam
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