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On 9/30/15 8:43 AM, Chris Boden wrote:
Greetings gentlemen,
As part of the new High Voltage Lab at The Geek Group, I am looking for the
perfect current limiter for our test rig. My dream is a variable inductive
ballast system that can operate at anywhere from 0-560VAC 3Ph (we have
input voltage control sorted out already), limiting currents up to 400A
down to as low as possible. It doesn't have to be infinately variable, it
could be stepped. I would prefer steps of something like 5A, certainly not
larger than 10A.
What about something that looks like a resistor substitution box with
either a 1:2:4:8 sort of setup, or an R/2R network like used in a DAC
With some clever design, you can set things up so that the big inductors
(needed to get the current down low) don't have to be wound with
enormous wire.
560V @ 5A is about 100 ohms impedance. At 60Hz, that's 0.3 Henry.
Why, in particular, do you need an inductive ballast?
The hot ticket would be to use a PWM bridge that can synthesize any
current/voltage profile. I'll bet there's some variable speed drives out
there that can do this.
I want to do this either with a custom built rig, or with something we can
get that is specifically designed for this application. The jank system of
old welders simply will not cut for this application.
Any ideas on where to get such a beast?