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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by mattinker on Today at 04:39:59 AM »
So now the priority is to mend or replace the contactor.

B/ 3D model it, print in PLA and get it lost PLA cast in bronze.

Lost Pla's the way to go!

Cheers, Matthew
I'm leaning towards option B - it worked well when I needed that drive dog for the Beaver lathe live tooling. I'm not even sure my copy of Fusion 360 is still operable - not used it for over a year and they have a habit of chucking you out !
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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by hermetic on Today at 04:35:20 AM »
Could you not superglue it back together just to see how it works, my feeling is that the slope on the hook contacts the broken off pieces and is pushed to one side till it passes the "obstruction", and then latches, but it is very difficult to sus it out without having the mechanism in front of you! Could you cast one in aluminium using the repaired original as a pattern? At this scale the shrinkage may not be that important, you could add a few coats of high build paint to thicken it up a bit!
Phil
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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by vintageandclassicrepairs on December 01, 2022, 05:18:56 PM »
Hi Andrew,
I despaired when I saw the contactor in bits  :(
I wonder if there is moisture getting into the unit? due to the condition of the trip unit?
Does it have an internal heater to prevent condensation? if not I would add one (main fed)
I really hope you are sucessful in getting the furnace going again
If I had access to my old workplace I'm sure something could be found that would work? sadly that's not possible

John
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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by awemawson on December 01, 2022, 11:41:55 AM »
So now the priority is to mend or replace the contactor.

Were it not for it's remote tripping facility it seems that there are quite a few just as 'manual isolators' - but the tripping is the only thing that the eStop button acts on and I'd like to retain that !

World wide searches haven't turned up any used ones, and although new compatible ones seem to be available their price rules them out at several hundreds of pounds.

The bit that is broken is a zinc or maybe aluminium based die casting - boxing it up is occupies about 50 x 50 x 65 mm. The hole for the big spring is 40 mm o/d by 36 mm deep.

Options:

A/ Machine one from the solid - time consuming but many of the features are there to minimise material use so wouldn't need to be incorporated.

B/ 3D model it, print in PLA and get it lost PLA cast in bronze.

I'm leaning towards option B - it worked well when I needed that drive dog for the Beaver lathe live tooling. I'm not even sure my copy of Fusion 360 is still operable - not used it for over a year and they have a habit of chucking you out !

As always comments and suggestions would be very much welcomed.

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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by awemawson on December 01, 2022, 09:04:42 AM »
Yes I agree Russ.

Well out I went after lunch armed with circuit (just block diagram sadly) to test voltages and try and locate all the fuses. Poked and prodded before applying power and - guess what - it went ready once I'd given it water flow and pressure and pressed the reset button.

I'd been lead astray earlier by all the lights on for the power supplies and microprocessor on the front panel thinking we were awash with errors - but actually being 'green' they are showing 'OK' - the red ones show errors when on  :bang:



Nothing had measured wrong - all supplies were there - no idea what has changed, and of course this may only be a temporary respite but at least it gives me hope. Obviously the program and basic microprocessor are still able to function.

I pinged the resonant frequency of the crucible, and did a very brief 'heat' (16 amp supply remember)

Having typed this out, I've just been back and repeated the process and amazingly it's still working. Again a very brief 'heat' as 70 amps from a 16 amp supply cable is not good  :bugeye:

Still need to sort the contactor out, but at least this makes it worth doing.

Now faults don't just go away - something is lurking - but at least the fundamental electronics seems OK (ish)
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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by russ57 on December 01, 2022, 05:40:48 AM »
In general, sudden onset of lots of faults is unlikely, although 1 fault could cause lots of damage.

I'd be looking for a power supply issue.
A missing rail, etc.

Or a loose / faulty connector. Is there any other components /modules near that corroded solenoid?

Otherwise a possible sad end to an epic journey...

-russ

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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by awemawson on December 01, 2022, 05:27:58 AM »

This morning I lashed the 'trip coil' back into the circuit as relay K1 needs it's continuity, and made temporary links round where the failed big contactor had been.

I powered it up via the 30mA RCD protected 16 amp three phase supply that normally feeds my guillotine as it's close enough to see & hear what's happening but far enough away for safety.

This was just for testing to see what faults are being displayed - and very sadly it's LOTS  :bang:



Much more head scratching needed - sadly it's possible that this will be the end of this journey, as I have no circuit diagrams of the main microprocessor equipped logic board, nor have I ever seen another one after years of watching.

. . .early days yet, I need to retreat, lick my wounds, and cogitate!
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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by awemawson on November 30, 2022, 10:32:03 AM »
OK a bit more dismantling - the contactor is in pieces all over my bench  :bugeye:

Essentially there is a plate that slides that has three sets of contact pieces on both sides arranged so one way up it gives a 'normally closed' contactor, and in my use the other way up gives a normally 'open contactor'. These contacts on their plate slide impaling themselves on the 'bridge piece' thus making a circuit. There is an over centre spring loaded toggle arrangement keeping them slide to the operating side, but when the no volt coil or the manual lever hits the release they spring apart.

There is a spring loaded 'hook interlock' preventing the slider  returning to the operating position which when the contactor goes to 'reset' should be lifted out of the way. At the moment I cannot see what is supposed to lift this hook, and indeed it isn't lifting.

The toggle has two springs, and the one on the right sits in a die cast cup with guide lugs and travel limiting lugs. The travel limiting lugs have broken off  :bang:

More work to fully understand this device but I'm nearly there.

If I really have to I can either machine from solid, or 3D print and lost wax cast a replacement cup but I will probably work out how I can try the furnace without this contactor before c omitting the time and effort to what might be a lost cause.

Remember - all this started mid melt so the contactor was closed anyway so there may well be more serious problems once this one is over come.
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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by awemawson on November 30, 2022, 08:28:02 AM »
Phil, I've looked for such cunningnesses but not found anything. I reinstalled the trip for precisely this reason, using the external lever to put it in the 'volts present' position (rather than 24v activated' and it's still the same.

I'm off back to the workshop for more experiments now though so watch this space !
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New from Old / Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Last post by hermetic on November 30, 2022, 07:50:45 AM »
Hi Andrew, very often in this type of breaker there is an interlink mechanism which stops the isolator operating unless the trip mechanism is in place, thus preventing nuisance tripping being cured by merely removing the coil. Is there anything that the trip coil depresses  as it is pushed into position? Does the act of resetting the trip push the solenoid core along and actuate the switch at the same time? Baffling!
phil
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