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Re: Fluke 27 and Transformer Oil
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> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Fluke 27 and Transformer Oil
> Date: Thursday, December 23, 1999 6:51 PM
>
> Original Poster: "Nathan Ball" <nateburg-at-hotmail-dot-com>
>
> Greetings!
>
> I am Nathan Ball, 16 year old coil builder and new to the list.
>
> I have a couple of questions:
>
> I have access to the use of a Fluke 27 DMM and was wondering if there was
a
> way I could use it to measure the output current on the 15/30 NSTs i
> rebuilt. It says in the manual that the max input voltage for AC mA is
> 600V...
sure you can use it, HOWEVER, there are some good reasons not to..
1) The NST outputs are both above ground, so your meter case will need to
float above ground and be well insulated because of reason #2, below
2) When the meter is connected, there is essentially a short circuit across
the output of the NST, so the voltage will be low.. However, if an open
develops anywhere in the circuit (loose connector, a bit of resistance in
the cable, one side of the NST fails, the voltage on the meter will rapidly
rise. If there is a possibility for an arc, it will, destroying the meter.
You could have significant corona discharge within the case of the meter
and not even know it.
3) If you forget, and touch the meter while you're making a measurement,
and the meter happens to be "hot", that measurement may be your last,
depending on the current
You don't need gnat's eyelash accuracy for this. Go get a cheap analog
meter from radio shack and use it. You can use a DC meter with a bridge
rectifier. Calibrate it at low voltages using a low voltage transformer.
Mount the meter in a plastic box with appropriate insulation and have at
it. A bunch of robust HV measuring tools are handy things for
experimentation.
BTW, I blew up a nice Fluke measuring the output current from a Van deGraaf
generator this way. It worked fine til the ground wire fell off, and then
it arced through the meter...