The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
awemawson:
I don't fancy introducing other bits into the breaker though I see your point.
My first thought had been Lumiweld, and indeed I have some, but decided not to do it at this stage incase it all droops into a puddle and I'd have lost my chance to check dimensions. When I have a working PETG model then I may well try it.
howsitwork?:
Andrew
Having just returned to forum after a while away. I’m fascinated and terrified at the same time !
That’s some serious power you’re playing with but makes interesting reading . Stay safe .
And of course good luck !
Ian
awemawson:
Yes it's all a bit scary Ian - definitely a 'one hand in you pocket' approach to probing needed !
Well there has been major progress on the 3D model of the bust 'spring pot' - I have a model that I'm sure will work when cast in something substantial like bronze.
However there has been another set back - I've found that the 'spring pot was not the only thing that has been damaged - and this time it's not going to be feasible to repair it :bang:
The plastic moulding of the isolator has broken in two places: firstly where the tube that slides the contact plate has over travelled, it slides in a groove and one end of the groove has broken away and the main body has cracked below it. Secondly there is a plastic formed collar around the operating spindle that has a stop lug on it that has broken off. The plastic is rather crumbly.
SO - I've come to the conclusion that even if I can have my 3D model 'lost PLA cast' and somehow re-build the plastic body of the contactor it will not be safe - so it has to go :bugeye:
. . the search is on for a replacement . .
awemawson:
Now really I want a 'through door operated' 250 amp 3 pole 415 volt isolator with a 24 volt AC under volt coil'. Without re-mortgaging these fall into the unobtainium category.
Much more common are ones intended for toggle operation inside a cabinet with 'shunt coil tripping' - and I've ordered and am yet to receive an ABB SACE S3 225 amp isolator that is equipped with a 24 volt AC shunt. It's 'only' rated at 225 amps but then my generator is putting out about 150 amps on full load so I don't think that's an issue.
Now there are 'through door kits' for these breakers and I will certainly keep my eyes open for one but meanwhile just have to open the door to power up. It IS rather dodgy as the cabinet has loads of HV exposed bits - I may have to make up perspex covers.
The 'Shunt Trip' is needed for the Emergency Stop function, and applying 24 volts AC trips the breaker. In the original the 'under voltage coil' works in the opposite sense tripping the breaker if it is NOT powered so I will have to introduce a relay to invert the operation. Again 'under voltage coils' are available for this isolator but I've not found them for under several hundred pound which is a ridiculous price.
awemawson:
As I will be re-working the circuit round the eStop I wanted to bottom out that peculiarity whereby the circuit diagram showed the ESTOP relay coil in series with the under voltage trip coil which obviously couldn't be correct as both are 24 volt ac devices powered from a 24 volt AC source.
Some work this morning with bright light and a meter has resulted in me finding the errors on the circuit and correcting it so at least I have a true starting point !
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