Current Limiting Queries

From:  FutureT [SMTP:FutureT-at-aol-dot-com]
Sent:  Thursday, January 22, 1998 10:33 PM
To:  tesla-at-pupman-dot-com
Subject:  Re: Current Limiting Queries

In a message dated 98-01-22 10:54:02 EST, you write:

> Lastly, can a pole pig be current limited by means other than an arc 
> welder or series power resistors?
> Cheers,
> Greg


The welder makes an excellent current limiter.  Another way to
make a ballast is to wind about 150 turns of #10 wire on a 3" PVC
pipe about 14" high.  Tap the coil every so often and connect these
tap points to a rotary switch.  Then fill the center of the pipe with
welding rods and/or threaded steel rods to create a steel core.  I've
used this type of ballast on pole and potential trannies with good
results.  An improvement would be to build a device that can raise
or lower the core to smoothly vary the inductance.

Another method is to use a variac as a current limiter, but this 
requires cutting a slot in the variac core to prevent saturation.

I don't like resistive current limiting because it wastes so much
power.  Many coilers find that the addition of some resistance
in series or in parallel with their inductive ballast smooths the
coil's performance.

John Freau