Resurrection of a CFEI 100 KVA Induction Furnace

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awemawson:
At last the trench is dug :ddb:

A friend of a friend came round this morning and kindly dug my trench - quite a big excavation initially to get a good angle to access the end of the 45 degree hole that I'd bored some days ago through the concrete. And of course it HAD to emerge just where years ago there had been a 6x6 fence post concreted in. Once the remnants of it's concreting in had been broken away life got a lot easier - the trench was brought up to about a spade depth and continued to the complicated corner where all the water pipes are currently exposed.

The corner of the concrete slab will need cutting off to bring the cable into the stable at a more benign angle and another friend is hopefully coming this afternoon to help me with that, and actually pull the cable though the hole.

awemawson:
My friends came this afternoon and between us we got the cable pulled through the hole in the concrete using a bit of waste pipe as a sleeve to protect its sheath.

About 4 metres extra was pulled through to allow the bend of the cable to turn 180 degrees for jointing in the resin joint. Once that joint has been made and tested the excess cable will be pulled back into the trench and into the stable.

The corner of the concrete by the stable was cut off and again the cable sheathed in a bit of waste pipe to protect it as the excess length is pulled back.

So, a resin joint to make off, a 125 amp wall mounted plug to make off, and two relatively short flexible umbilical cables to be made and apart from back filling the trench we are there :clap:

awemawson:
To more easily tackle the resin joint I decided to make an assembly jig to hold the two cables firmly, and pointing concentrically at each other. A couple of plasma cut steel plates mounting four suitably spaced cable cleats elevated on bits of 4x2 and screwed to a board.

It's just as well that I did this as assembly was a bit of a pain. I came across an issue that has never occurred to me before - the two ends of a cable are DIFFERENT. In this case looking at one end the cores read clockwise L1, L2, L3, N BUT the other end reads (again clockwise) L1, N, L3, L2. Now usually this doesn't matter a jot, but in this case where four heavy cores are being crimped in a tight space, and are separated by a cross shaped piece of insulation, two of the cores have to cross over no longer leaving a space for your cross shaped insulator :bang: Had I realised this earlier I could have threaded the last cable starting at the other end, and the cores would have all been flowing the same - but too late for that. A bit of ingenuity re-manufacturing the cross shaped insulation and forming the cores with a mallet to ensure adequate spacing, and an assembly was formed that was JUST compact enough to go in the plastic shell ready for pouring the resin. Before the actual pour I did an insulation test at 1000 volts and got well over 500 M ohms.

It is now probably already cured, but I will leave it overnight just to be sure as manipulating it into place and pulling back the excess four metres of cable is likely to put a bit of strain on it - certainly it will need a further insulation test before powering up.

. . . hopefully that's one more milestone ticked off the list :thumbup:

modeng200023:
There is always something trying to trip you up :doh:
John

awemawson:
John, if life was simple it wouldn't be fun :lol:

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