On 30/10/14 22:49, Hul Tytus wrote:
Eric - a "soft start" on/off switch might be a possible cure. In concept
it turns on the current when the cycle is nearly over and then turns of as
the current passes zero. On the next cycle the current is turned a little
earlier. After ?? cycles full power is turned on for all cycles.
Mouser Electronics shows a 40 amp triac, which is the "switch" in a
soft start device, for roughly $2. Probably need a micro controller to
control the triac - $.50, along with a pc board & some caps & a transistor
or 2. Then a "heat sink" and, probably, a healthy fan.
All told, the cost isn't much so someone has probably built such a
gadget for sale as an "add on". If you can't find one, look for someone to
build it and offer to do some testing for him.

Hul

wrote:
A friend of mine here on Whidbey Island has a welding business. It's
pretty new, only a few years now. Anyway, he called me yesterday with
an electrical problem. Puget Sound Energy (PSE) has had complaints
from neighbors about voltage spikes or drops, my friend wasn't clear
on this, but they showed him a graph which I have yet to see. The
solution PSE is proposing is a new xmfr at the pole. PSE told my
friend the problem is because of the hard starting welder. The welder
is an older xmfr type machine with lots of copper. At full load it is
rated at 11 kw, which is about 46 amps. But I don't know what the
current spkies to when he first steps on the pedal. The machine is now
wired for single phase but can be wired for three phase. What he wants
to know is if he ran the welder from a Rotary Phase Converter would
the current spikes and voltage drops be less. I don't know. I also
don't know if there is a way besides my friend paying thousands for
PSE to install a new xmfr on the pole for this situation to be
ameliorated. He can't afford at this time for a new welder with a
softer start setting. Besides, the hard fast start means his employee
can make more welds. Any help would be greatly appreciated.
Thanks,
Eric
Sounds like a phase angle controller powering a transformer which while
it works, I've done it on a Xformer for a TIG supply to ramp up/down the
current, is electrically very noisy as you end up potentially putting
maximum AC voltage into the transformer suddenly rather than the normal
build up from zero so high transient currents. I didn't see the effect
on the flourescent lights as I was welding but when it was pointed out
to me and I had a look they did significantly flicker during the
transition phase from 0 to full on power. No neighbours complained and I
checked with one about HF interference with their TV and no problems.
Subsequently I have gone to an inverter TIG and at higher currents
upsets the ADSL modem in the house but I don't know of anyone else
having any issues. Likely I should fit a suitable filter at the welder
supply but I'm the only one with the issue with losing ADSL connection
when welding at higher currents. I think a soft start might work in a
more friendly manner.