As you know, I have several of you pwm-servo amps.
I have never hooked up pin 8-9 because that has not been much of a
problem. Probably my fault. I can't see the red led indicating a trip
unless I get up a couple steps on a ladder. Room for mice in my
garage/shop is sparse so the psu & such are on a top shelf nearly 7 feet up.
I was running the spindle at 2 or 3 rpm in high gear yesterday while
trying to straighten the wire I use for contact probing, so the pwm was
running on an occasional 1 microsecond pulse, no load on the motor, but
somehow it tripped and I spent a couple hours, hal printout in hand
trying to figure out the why before I remembered that led. Crawled uo to
look, sure enough it was on. I had drilled a hole so
I could stick a wd-40 stinger in and reset it. So the question is, will
a removal of the 12 volts reset it?, and can it be done with the 127 VDC
still applied? The 12 volts is never off, currently coming from a 12
volt supply in the interface box that is on anytime the box has power. I
read the docs on your site again just now and would interpret the
warnings there and interpret that to be a no-no as long as the motor
supply has any unused voltage left. That might take 30 minutes or more,
that bank of caps is very well formed after a decade within volts of
their max rating & there's no other load to bleed it off.
I start that motor supply with a 200 watt, 50 ohm resistor in series
with the line, shorting it with a 2nd 60 amp SSR 4 seconds later, there
is so much capacitance there it trips a 30 amp breaker in the service if
not soft-started. I do the same with the line power to the other motor
psu's but with a 70 ohm limiter and less delay but that 12 volt in the
interface is not on that circuit, so the trip does not get reset by a
normal stop/restart. Have you ever given a thought to resetting that
with the unused pin 10?. And some hal logic to check the pin 8-9 status,
and delay the rest of the power up sequence if it needs reset. The way I
am doing this on most of my machines is the machine is cold if F2 has
not then toggled on.
Many thanks for any advice Jon. Take care & stay well.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
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