Author Topic: Resurrection of a CFEI 100 KVA Induction Furnace (Read 211922 times)

hermetic · « **Reply #750 on:** February 20, 2021, 02:52:05 PM »

Jammy dog, I had to pay £17.95 for mine!!

awemawson · « **Reply #751 on:** February 21, 2021, 06:13:45 AM »

They are only a tenner iirc anyway Phil.

So not being able to get on with the hearth itself due too lack of materials I decided to re-make the coupler that joins the torch gas lever valve to the torch flexible hose, but incorporating a choke or jet to reduce the gas flow. As it was, if the gas was fully on a dangerously long yellow flame was produced. The 1/2" BSP lever valve presents a female socket, and the original adaptor was a short stub of 1/2" pipe threaded both ends with a slight socket boring into one end to receive the 60 degree male cone on the flexible pipe. A bit crude and of course 'full bore' at 1/2".

I made one from a bit of hexagonal steel which gives the advantage of flats to put a spanner on when tightening. Jet end drilled 3 mm, female cone end drilled 6 mm then bored to give a good area of 60 degree taper with a big centre drill (BS7 3/4" Body).

Now if lit with cocks fully opened at least the flame isn't stupidly large and can still be controlled by the lever valve on the manifold and the knob on the torch itself.

awemawson · « **Reply #752 on:** February 24, 2021, 09:16:07 AM »

Well Flamefast came up Trumps

(cards that is not politicians !)

Were I to make a donation to a nominated charity they would pop some bits in a box and send them to me - a refreshing way of doing business ! That was Monday afternoon, today (Wednesday a box arrived containing 5 kgs of rather special 'RCF Mastic', an 18" square of 4 mm pretty solid Kaowool blanket, Two face masks, two pairs of nitrile gloves AND the proper propane jet

A bit of careful marking out and cutting and the kaowool was reduced to a 12.5" disk with a 7" hole in it ready for use as a thermal barrier between the ceramic tile and the metal plenum chamber.

I then 'caulked' the joint between the plenum chamber and the quadrant tiles with the RCF mastic forcing it as far into the joint as possible as it is this seal that had previously been leaking.

Then fitting the Kaowool disk with the perforated tile on top I caulked all round the tile forcing as much as possible down into the gap. Having got as much in as I could with a putty knife I then forced it further in with a wooden lath cut to size. Another two trips round the tile with the putty knife pushing the mastic in as far as possible followed by smoothing with a wet trowel and a damp cloth. This seal HAS to be good or the whole rigmarole that I've been through will be a waste of time.

Asking how long to leave the mastic I was told that in the factory they hit it with a gas torch, make it sweat, and then it's ready ! OK I used the forge torch to dry the surface then put the ceramic chips back in and lit the forge, reasoning that hot chips are no different than a darn big gas flame to dry and cure the mastic.

Initially clouds of rather nasty smelling steam then after about 5 minutes things began to clear and the chips started to glow. After ten minutes I'd swear it's hotter over a more even area than i can ever remember it. So with much of the bulk of the ceramic chips glowing white hot I turned it off in the interest of conserving propane - I'm sure that the mastic will now set nicely.

awemawson · « **Reply #753 on:** February 24, 2021, 09:23:50 AM »

Comparing the 'original' propane jet that was in the forge when I got it to the one sent by Flamefast convinces me that someone has altered the holder from 1/2" BSP to M 12, but what is important is the hole for the gas - how big is it?

My currently installed one is 3.5 mm as that was as close as I could get to a #28 drill. I'd been told recently by Flamefast that the jet should be 3 mm, but NO! This jet actually measures #29 (yes I now have a set of number drills!) or extremely close to 3.5 mm so I'm not going to change anything.

hermetic · « **Reply #754 on:** February 24, 2021, 02:38:18 PM »

Another useful peice of kit brought back to life Andrew! There is nothing worse than finding a job you have to do and then saying "this would be easy if only X was working" And now it's Perfick!!
Phil

Pete. · « **Reply #755 on:** February 24, 2021, 05:26:27 PM »

"May cause cancer by inhalation" - that can only mean it's the GOOD stuff

awemawson · « **Reply #756 on:** March 30, 2021, 09:59:57 AM »

So there was I melting the greenhouse . . . . . .

. . . . . OK let me explain, some years ago we had a greenhouse that was a bit of absolute imported rubbish - it didn't last the first winters storms - and for several years now there have been bits of green anodised aluminium channel section getting in the way and being tripped over in the horticultural area. Time to sort them out (I was told).

Now no point in chucking it out, turn it into ingots and save it for later use. Cut up with the band saw into convenient 'crucible lengths' today was it's appointment with doom. I even welded up an extra ingot mould as there was 3 kgs in the bundle.

All put in the pot, coolant water from the borehole circulating, 110 kva generator purring away . . throw the switch Igor

Wound it up to 50, then 60 then 75 kw - channel section sinking nicely into the melt - hang on - what's that burning rubber smell ?

Now there had been flames off the channel sections, not unexpected with the dross of years on the surface but this was distinctly burning rubber - what's going on and why are there flames down there among the various driver hoses ?

It turns out that one of the driver cables that is enclosed in 'Brewers Hose' for water to circulate to keep it cool, was resting against the 'air hose' (actually braided hydraulic hose that I'd used for robustness), and there must have been enough electromagnetic coupling from the driver hose to the metallic braiding to heat it up and set the rubber sheath on fire !

Turn off the furnace driver, give the hose a blast from the CO2 extinguisher and the flames subside - move the hoses apart - tentatively tilt / untilt the furnace (which uses this hose for the pneumatic cylinder) - OK still working - turn the furnace driver back on while the crucible is still hot, and pour the ingots (second one looks lousy quality)

. . . the good part of this is that it has only cosmetically marked the Brewers Hose (which is darn expense) - OK the air (hydraulic) hose is toast (literally!) but I have miles of that so it's not an issue.

OK Greenhouse melted, domestic demands satisfied, just need to swage up a new hose !

mattinker · « **Reply #757 on:** March 30, 2021, 10:39:40 AM »

Andrew,

I know you are fortunate enough to be able to analyse your metal content! Extrusions are usually pretty pure Al. Did you add any Cu? I find 4to 5% Cu makes a harder more easily machinable alloy!

Cheers, Matthew

awemawson · « **Reply #758 on:** March 30, 2021, 12:34:54 PM »

Matthew it's still in the ingot moulds. I made my judgement on how horribly it poured but as you say extrusions are usually LM2 or similar.

awemawson · « **Reply #759 on:** March 31, 2021, 06:11:34 AM »

Added to today's tasks was of course making good yesterday's damage

Taking the hose off and duplicating it was easy, as I had the crimp ends and 1/4" hydraulic hose in stock, and I also have the proper 'Parker' crimper. It's a bit of a fiddle to manipulate but good solid kit that gives a nice reliable result.

The second air hose running along side this one had suffered a bit of collateral damage but I judged it safe to use - mainly cosmetic scarring.

Now having put it all back together the obvious question is how to avoid the problem in the future

I had left the four Brewers Hose power feed cables unstrapped to give more movement flexibility but it occurred to me that these are basically a transmission line (well a pair of transmission lines) and they avoid radiating by the fields of parallel conductors cancelling out (i'm assuming here that the damage WAS stray energy radiation from these leads inducing large currents in the braid of the air hose) so the first thing that I did was Ty-Wrap them into pairs.

However watching the action of the crucible assembly raising and lowering (it tilts) in the down position the power cables press firmly against the air hose which is less than desirable from many point of view. However stopping this is by no means simple. I need the hoses to emerge at a different angle from the base of the tilting assebly.

If I can source some brass 3/4" BSP cone connections that are at 45 degrees then that might be a possible solution but I reckon that they are probably as rare as hens teeth !

chipenter · « **Reply #760 on:** March 31, 2021, 09:59:44 AM »

Would two ninety's have enough room to be set at any angle you want .

awemawson · « **Reply #761 on:** March 31, 2021, 11:15:15 AM »

Jeff that certainly is a possibility, though the whole structure is becoming rather cumbersome. (Remember that these carry thousands of amps as well as the cooling water)

I'm wondering if I can construct a non conducting (but heat proof) gently curved shelf over the air lines to keep the power cables a fair distance when it comes down.

I also want to conduct an experiment with a bit of the braided air hose held close to the power cables when the furnace is at full tilt to see how far away is 'reasonable' - presumably the inverse square law applies. But that is a two person job to be safe as one needs to keep an eye on the generator / cooling system / furnace driver while the other dangles bits of hose and and measures how hot they get!

WeldingRod · « **Reply #762 on:** April 01, 2021, 10:36:19 PM »

Zip tie scraps in place with wood spacers? If the zip tie melts you know it's too hot ;-)

Sent from my SM-G892A using Tapatalk

awemawson · « **Reply #763 on:** July 25, 2021, 02:46:53 PM »

You may recall the problems that I had with the roof of my foundry - lots of leaks, lots of repair attempts etc, it ground on like a cracked record.

Well today we had an absolute deluge in a short space of time. My rain gauge has recorded 43.4 mm in the last 24 hours but a lot of that happened in about 20 minutes.

Hearing how poor old Graham (Seadog) has suffered with his workshop roof leaking badly I thought I'd better go out and see how the foundry was fairing.

Delighted to say just a minor (tolerable) damp patch in one corner, so it looks like the big issues are solved - fingers crossed)

Sea.dog · « **Reply #764 on:** July 26, 2021, 05:47:04 AM »

Good news, Andrew. I think that you now can be fairly certain that the foundry is water tight, to all but downpours of biblical proportions, that is

edward · « **Reply #765 on:** July 26, 2021, 09:47:26 AM »

One thing that comes out of these rather excellent threads is that I find out about things I never knew I needed - I've had one of those rain gauges since you mentioned it, alongside my existing 'weather station' on my bedside table.

Now I don't even need to get out of bed to see if it is raining or not :-)

awemawson · « **Reply #766 on:** November 28, 2022, 12:10:21 PM »

We've had a lot of rain recently with winds from odd directions, and I was pleased to find on my 'rounds' that although a little had blown into the foundry the major points of previous water entry were dry. Particularly pleasing that the extensive 'french drain' along the side wall has proved to be effective with no water penetrating at the base as it had previously.

However less pleasing was a fault I now seem to have with the CEIF 'furnace driver'. I start the 110kW diesel generator every couple of weeks or so just to blow the cobwebs out, and occassionally run up the induction furnace it self with a bar in it as a 'load' just to keep capacitors polarised and introduce a bit of warmth to keep the damp at bay.

This time all started OK, I ran it up to 30 kW producing a nice red hot bar in the pot, but rhen odd things started to happen. Various errors displayed and the main breaker tripped out. Power cycling it again it started off OK but then all sorts of fault indications mainly round the input voltage and current monitoring.

Now I can't even get the main breaker to latch 'ON'. There is a tripping device - solenoid sort of thing - and I'm not sure in which sense it is supposed to work. I suspect that it needs power to the beast (where two phases are stepped down to 24v AC to power this device which is in series with the emergancy stop button) and this latches it.

Not easy for fault finding as being 415v and HUGE amps everything is well shrouded. I'll resume fault finding tomorrow and power it from my local (low power 16a) 3 phase supply so at least there will be a 30mA RCD trying to keep me alive as I do it. Obviously I can't run at much of a level with that supply but I did once (by mistake!) run it up to 12 KW

Never mind - I ran the ceramic chip propane hearth up to glowing white heat to burn off a few cobwebs and at least THAT did work

Sea.dog · « **Reply #767 on:** November 29, 2022, 05:16:04 AM »

That must be rather frustrating, Andrew. At least you're aware of the problem and didn't come up against it when you wanted to use the beast in anger.

Good luck!

awemawson · « **Reply #768 on:** November 29, 2022, 06:00:33 AM »

Yes Graham, it's a bit of a pain !

This morning I've wired it up with a low power 16a 415v feed for testing. 3 phase comes in to a blooming great manual isolator switch QS1 which is a SOCOMEC 35043025 rated at 250 amps equipped with a 24 volt 'manque de tension' (lack of volts) coil (SOCOMEC 39913024) that should trip it and prevent connection if mains isn't present.

After several attempts to manually latch the isolator I did on one occasion manage it and the system was showing loss of lots of DC supplies despite the PSU's tell tale leds being on.

The 'manque de tension' coil is fed from a transformer (TC3) a fuse in the 415 feed (FU4) and a fuse (FU5) in the 24volt AC line. The transformer is permanently across two phases before the isolator.

I can hear a 'click' as I remotely apply power which is probably the 'manque de tension' solenoid, but may be the relay K1 pulling is, as very oddly the circuit shows K1 coil in series with the 'manque de tension' coil but both are rated at 24 volts and the series chain is fed from 24v AC

However I can't manage now to latch the isolator - it's possibly a mechanical fault with it but that doesn't tie up with the onset symptoms of yesterday when the furnace was initially working.

Testing suspended due to other commitments

https://www.socomec.com/files/live/sites/systemsite/files/SCP/pdf_catalogue/GB/cat_sidermat_en.pdf

mattinker · « **Reply #769 on:** November 29, 2022, 06:44:58 AM »

Andrew,

As you say, it doesn't make sense to have 2 24volt coils in series. Is the TC3 actually 24volts or there about?

Cheers, Matthew

awemawson · « **Reply #770 on:** November 29, 2022, 07:24:49 AM »

Yes it's all very odd Matthew

I measure the transformer output as 26 volts AC. By using the emergency stop button (which is in the chain in question) I can power up / down the 'no volts solenoid' and the relay K1 which has a 500 mSec delay built in and it is apparent that the delay is working.

Quite possible that the circuit has been drawn wrong and that the coils are in parallel, or maybe the coil and contact of K1 are interchanged in the drawing. It wouldn't be the first error I've found in the drawings!

I strongly suspect that I'm going to have to pull the big contactor out and try it on the bench - I really don't waant to as it's far from simple and I suspect that it's a red herring as far as the original fault is concerned.

At least the transformer, fuses and relay K1 are all close together on one panel for fault finding but the 'no volt coil' isn't really accessible without pulling the entire contactor.

awemawson · « **Reply #771 on:** November 30, 2022, 06:09:07 AM »

So nothing for it - pull that huge isolator out for examination !

First ABSOLUTELY ensure no main can be connected. Then it's just a case of unbolting the three phase input lines, three phase busbar output lines, disconnecting the trip coil connections, and removing four M6 bolts securing the beast to the chassis.

OK isolator removed

awemawson · « **Reply #772 on:** November 30, 2022, 06:25:53 AM »

Now at last I can see where the trip coil is located - round the back !

The trip coil unit clips in with it's two wire threaded though a channel to the front terminals. Pulling it out it is all rather sad - obviously suffered water damage and from it's terminals is open circuit. However scratching about, the actual coil is OK (2K ohms) and the solenoid pulls in nicely from 20v DC (bench supply) so I'm confident that I can clean it up to serviceable condition.

With the trip coil removed I can physically latch the mechanism 'ON' and trip it to 'OFF' by holding the lever that the solenoid presses on in the appropriate position - ah good I (ERRONEOUSLY) think.

When latched 'ON' there is no electrical connection between input and output on any of the three phases, and indeed the 'double break' contact arrangement that I assume should slide to the left to impale the contacts onto a bridge piece hasn't moved. This is VERY odd - I must be missing something here

As far as I can tell the entire plastic assembly that holds the three sets of 'double break' contacts should slide to the left onto the bridge pieces but it doesn't - this has me greatly confused

Time to sit and cogitate I think

hermetic · « **Reply #773 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

awemawson · « **Reply #774 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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Author Topic: Resurrection of a CFEI 100 KVA Induction Furnace (Read 211922 times)