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Re: [TCML] pole pig question
First of all, a SINGLE 7.8 kVA is going to be pretty inadequate
to handle what a 25 kVA pig is capable of. I assume that you are
already aware of this and that this setup is for test purposes only.
I'm not sure that I understand exactly how you are hooking up your
"test" capacitor but it appears that you are only hooking the output
of the transformer to the capacitor leads and nothing else. Direct
connection to a capacitor, and letting the capacitor alone be the load,
without a safe "outlet" of a reasonable inductance for the capacitor to
dump its load into, via a properly set spark gap or a *dummy load*
resistor, can be a pretty unhealthy environment for both the transfor-
mer and the capacitor. This is due to resonant voltage rise, which also
may very well explain the 10% increase in the down stream voltage
of the ballast vs. the input voltage.
I believe your pig is fine but you need to change your "test" setup.
Others will probably crunch some numbers for you.
----- Original Message -----
From: "Jim Calvin" <jcalvin@xxxxxxxxxxxxxxx>
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Sent: Wednesday, January 16, 2008 4:25 PM
Subject: [TCML] pole pig question
I am trying to test my 25KVA pole pig. I am not running my
coil yet. I wanted to test the system out. So this is how I have it
I have a 240Vac input with a 7.8kKVA variac with a control switch. I am
using the variac to regulate the voltage. I have a 6.5mH choke (hand made
using 10 gauge wire) in series with the primary. I have a .05uF (at 50KV)
capacitor connected to the HV output of the pig as a test load. One of the
HV outputs is connected to GND along with the pole pig can. My variac is
a control box with a voltmeter and a current meter. I have a fluke meter
across the input 240Vac of the pole pig after the ballast. Between the
volt meters I was going to check the voltage drop across the ballast see
the it was doing it's thing.
I set the varaic at a 100V using the meter in the control box before I
switch it on to the pole pig and ballast. When I switch it on I would
expect the voltage in my panel meter to stay the same and my fluke meter
be slightly less because of the drop across the ballast. I figure my load
should draw about 8 amps out of the variac.
Well when I turn the switch on the power to the pole pig and ballast, the
fluke meter is giving 110v and the meter in my control box jumps from 100
to 110V (aprox. It is an analog meter).
Then I decided to use my oscilloscope (I am part owner of design
company and I have access to this equipment) and check the voltage before
the ballast and after. Well the voltage after the ballast went up just
the fluke had shown.
What am I doing wrong? Is it possible that the HV output is leaking back
the primary? What is the isolation voltage between primary and secondary?
I got this pole pig from T&R electric. It was actually a gift from a
of friends/fellow coilers). It is supposed to be new/reconditions and
checked by them.
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