Subject: Re: Transformers
From: MSR7-at-PO.CWRU.EDU (Mark S. Rzeszotarski, Ph.D.)
Date: Thu, 8 Feb 1996 09:17:54 -0500
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>From: "SROYS" <SROYS-at-radiology.ab.umd.edu>
>Date: Wed, 7 Feb 1996 16:23:37 EDT
>What is the best way to try to see if a transformer (pole or potential)
>is good using only a DVOM? Is it just a matter of making sure the
>terminals aren't open circuited, and that the LV and HV sides aren't
>shorted together (assuming they're really not electrically connected),
>or is there more to it than that?
I just purchased a 9 kV 150 neon sign transformer (used) to add to
my collection. I used my volt-ohm meter to check it out initially. In
general, the secondary should read 5-20 kilohms (higher if it is a 10 kV 23
mA furnace ignition transformer, lower for high current models). The
primary will read less than 100 ohms, often just an ohm or two for a high
current model. I check to make sure the secondary resistance reading is the
same between ground and each high voltage terminal if it is center tapped.
I also check to make sure the primary is not shorted to the case.
In addition, I have made up a short power cord with 110 v plug on
one end, and alligator clips on the other ends. I bring along a short piece
of wire and hook up the transformer to verify that I get about the same arc
length off each side of the secondary. You should get an arc of about 3/8
inch for 9 kV, or 1/2 inch for 15 kv, ballpark.
Try to make friends with a neon sign shop owner, and let him/her
know what you are looking for. Try to get the 60 mA or higher current
models if you can, or 30 mA if you are building your first coil.
Mark S. Rzeszotarski, Ph.D.