Induction furnace power supply

[ironman]

A while back I went to a foundry auction to have a look at induction furnaces.

The power supply cubicles were unlocked so I took  a video of it inside as I have never seen inside one.

If anyone is thinking of building one you will need really good electronic skills plus time and money.

http://youtu.be/ytuslAUsIsQ

[tom osselton]

That one is bloody big! I would like to have one but as you say know what your doing but I still find myself on utube thinking hmmmm.  Seems not bad just don't stick the tounge on cap's to see if their charged.  I'll probably end up with a roy.

[awemawson]

When I've totally wrapped up my lathe project I'll dig into my 'round tuit' store and take some pictures of my 100kW induction furnace. Currently its blocked in with building materials

I may even start a thread on resurrecting it and setting it to work, it's about time, it's sat idle for 6 years now !

[ironman]

Was it that long? I remember when you had it running when you were living in Kent.

[MetalCaster]

Nice video ironman.

For an induction furnace of any size, you need a lot of money and a good 3-phase, 480 volt power supply.

I recognize quite a few of the components in the cabinets.
Those are very similar to the medium voltage variable frequency drives I specify.

I would love to have an induction furnace, but I am afraid I am stuck with my poor man's induction furnace (an oil burner type furnace).

But KW is KW right, and if you can generate 320 KW with an oil burner for the price of a little diesel fuel, then who can complain.

[awemawson]

Was it that long? I remember when you had it running when you were living in Kent.

Sadly yes! A lot has happened in that time (it'll be 6 years in October). All the kit is here, I have the space to locate it, I even have  had a three phase supply run in big enough to run it. I just need to push it up the priorities !

[lordedmond]

if you think that one is big you should see a 1.5 mega watt job,

I used to look after 1 of the above and 2 off 1 mega watt jobs and the three 750kw ones that I installed

they all have a sub station the held the transformer and pf control caps these and the main coils were water cooled

we also had a small 100 kw high frequency one for the research dept  that did run off 415  3 ph  all the others ran from a 3.3kv source with a coil volts at unity pf of about 1kv

for those that do not know the are all parallel resonant machines that why you see plenty of copper busbars between the coil and cap banks to cope with the very large resonant circulating currents

They were pretty tame in there operation unless a bale of scrap steel was drop in with a tin can in with water in it then boom 11 ton of iron up in the air not good 

Stuart

[awemawson]

Mine runs at about 3 kHz. The electronics 'pings' the tuned circuit that comprises the coil round the crucible and the bank of capacitors in the drive unit to ensure that it's within it's limits, then sets itself up to resonate at the measured frequency by chopping the power electronics at the right rate. It then adapts to whatever charge is loaded into it.

Quite a bit of logic electronics as well as the power stuff. I have a 15kW water chiller to cool the water that circulates through the electronic unit and the coils round the crucible. Even so I have to be careful as it overheats quite readily. The capacitor bank is huge, with manually alterable links to bring various different inductance furnace bodies into its range.

Have a few pictures all dating from when I was at my last place. First picture is of it being delivered to me. Delevery chap could believe it was going to a private house !!!!!:

[tom osselton]

That is really nice I'd be happy with one that could fit in a suitcase!

[ironman]

Here ya go Tom this will fit in your briefcase.

I did the rounds in my area on rubbish collection day and found an induction cooktop. It operates on 220 volts and input power is 2000 watts. I think this would make a nice little induction heater. Have a look at the photos of it.

[tom osselton]

Morning Ironman well that does look like it would be interesting to play around with I don't see a lot of capacitors there but it would be interesting to see what a different coil would do or if they could be added. The flash can't be anyworse than getting my pic taken!!    

[ironman]

Tom have a look at the photo  pcb+ fan. There are two large caps with a filter coil in between.