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Re: Cheap Variac Substitute?/ vs Expensive.
Most variacs are NOT isolated. They are actually a form
of auto-transformer in which all windings are connected
together. Variable isolated supplies are a combination
of isolation transformer and variac.
Isolation does provide some protection against
kick-back into the mains circuit. I would recommend
grounding one of the isolated output lines, otherwise
you may exceed the breakdown voltage of the insulation!
When in operation on a Tesla coil the voltage across
the isolation transformer can be thousands of volts.
Grounding one line reduces the voltage differential to
less than 200 volts.
Fr. Tom McGahee
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Thursday, February 03, 2000 10:50 AM
Subject: Cheap Variac Substitute?/ vs Expensive.
>Original Poster: Harvey D Norris <Tesla4-at-excite-dot-com>
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>On Wed, 02 Feb 2000 05:27:58 -0700, Tesla List wrote:
>
>> Original Poster: "Dr. Resonance" <Dr.Resonance-at-next-wave-dot-net>
>>
>>
>>
>> Solid state control of TC's with such devices is perhaps not the best
>> recommendation. Central problem is that when the solid state device
>fails
>> it goes to full on conduction and you loose all control. This doesn't
>> happen with a variac so they usually represent better safety even though
>> they are a bit bulkier.
>>
>> Dr. Resonance
>>
>>
>I recently purchased 4 MONITOR ISO-V-AC III model WP 32 isolated power
>supplies that go to 150 volts-at- 10 Amps. These can function as variacs as I
>can turn the voltage up from 0 to 150 with a dial. I have several questions
>regarding operation. Do all variacs represent an isolated power supply? Is
>there an advantage to using such a supply
>to a NST primary and does this consist of a means of protection against RF
>kickback such that only a safety gap should then be needed
>as protection to NST damage on secondary? Could I put all 4 in series to
get
>600 volts, or would there be any problems with having to simultaneously
turn
>up the voltage on each device? Below the amperage meter is a leakage button
>and the meter has corresponding leakage amounts at the rate of 2.5 ma per
10
>amp output. What does that mean?
>Does it indicate the loss of effiency involved in the transformer?
>Thanx for any answers to these many questions.
>HDN
>Binary Resonant System
>http://www.insidetheweb-dot-com/mbs.cgi/mb124201
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