The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
vtsteam:
CNC Mill + touch probe + CAD + block of plastic = replacement plastic part
:proj:
mattinker:
--- Quote from: awemawson on December 07, 2022, 06:13:05 AM ---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 !
--- End quote ---
That makes more sense, real 24volt parallel !
cheers, Matthew
awemawson:
Matthew it's not the first error I've found in the circuit diagrams for this beast. If the draughtman was given a hand written sketch of the eStop circuit I can fully understand where he went wrong confusing cable 304 and 301 and bringing 307 to the wrong transformer leg !
I've managed to source a pretty inexpensive ABB SACE S3H 250 amp contactor that has a 'through door actuator' but no door hardware or handle or shunt trip but seems the same body size as the ABB SACE S3 225 contactor that I have on order that DOES have the 'shunt trip'. So I am hoping to assemble a 'frankenmonster' from the two ABB S3 breakers and the door gear from the original Socomec breaker.
Mounting is going to be fun, as to avoid cutting another hole in the door the left hand side operated ABB breaker will need mounting a lot further to the right as the original has a right hand side operating handle.
The other issue is that I really want to move the supply to the eStop transformer to the switched side of the isolator which is going to potentially introduce timing issues ensuring that the new shunt trip isn't momentarily powered as the breaker closes.
awemawson:
Well at long last I can make some progress with this repair.
EVRI / Hermes have lost BOTH contactors that I bought that were to be amalgamated to form one with a rotary operator and one with a 24 volt AC trip mechanism. The sellers of these used contactors fortunately both had additional items which I got sent by Post Office 24 and UPS - the UPS one arriving this morning.
This has allowed me to assemble a 'composite' having the trip and rotary actuator allowing the original Emergency Stop still to work, and the contactor to be operated 'through the door'. However this means I'm sticking with the original rather odd arrangement meaning that the emergency stop relay coil is powered even with the door isolator switch is off. As I'm generator powering the furnace this isn't too much of an issue as it only runs when the furnace is in use. Were it off the normal mains I'd somehow have to re-work it.
Now as you can see from the pictures the old and new contactors are vastly different in size, layout and termination. I have worked out a scheme where I think I can mount the new one so it's operating bar goes through the original door hole, and by re-wiring using 35 mm 'meter tails' with crimped tubular lugs can get it to fit - a bit of metal work to do for the actual physical mounting.
I've drawn it up in Autocad showing the outline and fixings for old and new putting their operating bars in the same location so I can lay out a 'hopefully' workable layout.
. . other duties call but I will return . . .
awemawson:
Got a bit of time after lunch to make up a mounting panel from 6 mm polycarbonite sheet.
Dimensions seem about right but can't mount properly due to a local shortage of 3/16 UNC nuts ! - I'll probably make some but time presses being a Friday with cottage guests arriving - need to change into 'mine host' mode !
Ty-Wrapped on as the 2-3/4 x 3/16 bolts are only poked through the holes to locate it - still the square operating bar DOES poke through the hole in the door so it's in the ball park :clap:
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