Resurrection of a CFEI 100 KVA Induction Furnace

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awemawson:
The 11:00 deadline came and went so I fired up the 110 kva generator and did a simple 'bar heating' exercise to put a bit of load on the connections and wiring - all seems well :thumbup:

The same bit of 16 mm mild steel bar that I'd used before was raised quickly to glowing point - a matter of a couple of minutes or there abouts.

There must be some sort of power limiting algorithm running on the furnace microprocessor - it 'topped out' at 59 kW this time - I suspect that it is based on the charge in the crucible. I must experiment when I have the place to myself with greater and lesser charges and see when the yellow 'limit' light comes on as I turn up the power.

edward:
Thanks Andrew - I love your threads and the forensic detail you go in to with your repairs.

There is no better reason for doing something than because you love it. I've been building bike wheels recently, mostly because I wanted to learn the skill rather than any actual need to do it, and when it all comes together its just so satisfying.

Your Hovercraft video gave me flashbacks to a trip I had across the channel on one of the big Hoverspeed craft with the venture Scouts when I was in my teens. It was really rough, half our unit were up the front enjoying crashing over the waves and the other half back aft somewhere, filling a lot of those paper bags with the contents of their guts. Luckily I've always had pretty good sea legs :)

modeng200023:
Now I'm sitting here willing my cottage guests to go out for the day so I can start up the big genny - I've sort of decided that if they'e not gone out by 11:00 I'm doing it anyway !!!!!!!

Seems like a plan :clap:
John

awemawson:
Well they've actually all gone out now - one couple were still there when I did the previous run but they were indoors so may not even have heard anything - after all it was over in five minutes - that's the good thing with induction heating.

SO - let's do a second run with more mass in the crucible and see what happens. I added a 550 mm length of 33 mm hexagonal mild steel bar to the 16 mm round that was already in it, fired up Big Bertha and again ran to glowing heat - just a few minutes. Limit came on this time at 70 kW / 147 amps (had been 59 kW / 122 amps previously)

I'm now thinking maybe the electronics is measuring the resonant circuit peak voltage and putting a limit on that - it's not entirely consistent but first run the voltage was 646 v at limit, this run it was 639 v. Need much more data I think.

Anyway I learnt two three lessons in this exercise.

a/ Driver goes into limit at different powers depending on charge in crucible

b/ Don't worry TOO much about the noise - it's much less at distance and I'm up close.

c/ And DON'T poke your tape measure in the crucible to measure a bar length - even when everything is OFF it's still hot enough to remove the paint !

Spurry:

--- Quote from: awemawson on August 03, 2020, 08:27:08 AM ---
c/ And DON'T poke your tape measure in the crucible to measure a bar length - even when everything is OFF it's still hot enough to remove the paint !

--- End quote ---

So you are human after all! :D
Would also echo Edward's earlier comments about the thread, 'twill be a sad day when it ends.
Pete

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