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Welding from a Listeroid/ST generator rig

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olNick:
Bruce,

Bit further on this, FWIW, my first shotgun repair attempt (simply replacing the IGBT's), lasted about 5 seconds before blowing up, since I did not check that I had pwm drive, before enabling the HV (SMPS-101 lessons here)

I bit the bullet, and read up to understand how inverters/SMPS work. Poking around I found that GDT had shorted/opened I don't remember.
Replacing that transformer brought back the PWM, and the thing started working again, with new transistors

The welder is/was quite advanced for a early 90's design, with a very high duty cycle. Specifically stated 8KVA generator minimum, my bad..
The "6KVA" chinese honda that did the damage, essentially almost stalled at that time...

anyway, I don't qualify for even 2nd group above, ha...
nick

BruceM:
olNick,
Bravo on that repair. 
I expect a 90's design with IGBT's would not be power factor correcting, so it would need a much higher rating on the generator head to cope.

Inverter-welders have always been at the cutting edge of power designs.  I can't imagine a more difficult power design application; high current arcing and shorts are normal. 

 

mikenash:
Fwiw we use a couple of $400 180A inverter welders at work (one of which belongs to me, personally) off of a Chinese generator and have done so for over a decade at the cost of just one welder, which was very second-hand at the time, anyway.  We use an 11kVA generator and it doesn't really notice when the load comes on - no real drop in revs or whatever.  I have been told that is the secret to looking after both generator and welder.  Our local hire company won't hire you anything smaller than about 15kW if you tell them you're welding - they say it "blows up" the generators sometimes too.   Cheers

mauro:
Hello everyone. I have read various treads in this forum, written over the years, about flywheel balancing. There are some things I don't understand and I would be grateful to those who have already done this if he could help me. I got an axle with bearings where I will place the flywheel. The first question: if I put weight on the opposite side of the flywheel counterweight to cancel it, won't the engine start jumping even more? I think I understand that the flywheels have a counterweight to counteract the force of the piston and try to balance the crankshaft. It's correct? After having found the weight to add I read from 38ac "once you have the weight in the correct position and with respect to the key and equally weighted both flywheels, you attach them to the engine and adjust the offset weight to make the operation easier". How do I know how much counterweight and where should I put it when the flywheels are reassembled?
Thanks for any help.

cobbadog:
From what I understand about any flywheel is that the engine will run without one. By adding a flywheel you are adding 'inertia'' which aids in  the smoother running of an engine and also helps the engine to maintain speed when loaded until the governor opens up and lifts the RPM.
I fell there is no need to run 2 flywheels unless you want to add extra weight to make it run smoother for longer before need more RPM. I have a few stationary hit n miss engines. Some have one flywheel and others have 2. There are 2 engines with the same cubic capacity, fuel mixers and head and stroke and bore but have a single flywheel and the other a twin. O ne engine is rated at 1.5HP and the other at 2HP, only difference is the extra flywheel and one is air cooled the other hopper cooled.
In my opinion one flywheel would be sufficient remembering that flywheels are balanced before being fitted to an engine. As a comparision your tyre gets balanced on the wheel before it is fitted to the car which has many different choices to mount it. Hopw that makes sense for you.

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