One man's insanity---the story of an induction furnace

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rrnut-2
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Re: One man's insanity---the story of an induction furnace

Post by rrnut-2 » Mon Jan 29, 2018 11:41 am

Hi Harold,

That's great! The motor runs! Now I have to give you some details on how to construct a cooling system.

At least you did better on firing up the unit than a foundry in Vermont did. They informed Vermont Power that they were installing a 900Kw inverter, and was told that no electronic device draws that much power. Well, the service tech told me that he never got to 500Kw when the lights
went out...all over town! It blew the circuit breaker at the substation! The tech was accused of leaving a wrench on the bussbars...so they tried it
again. This time both the circuit breaker and transformer!

Jim B

John Hasler
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Re: One man's insanity---the story of an induction furnace

Post by John Hasler » Mon Jan 29, 2018 1:25 pm

Sounds like management and design problems at Vermont Power.

John Hasler
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Re: One man's insanity---the story of an induction furnace

Post by John Hasler » Mon Jan 29, 2018 1:41 pm

Big induction motors can be tricky to start across the line. You may want to think about shutting down other large loads such as HVAC and your well while starting this thing.

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GlennW
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Re: One man's insanity---the story of an induction furnace

Post by GlennW » Tue Jan 30, 2018 1:57 pm

Well, it damn sure looks nice, and I realize how much hard work you have put into it getting it cleaned up and operating.

Congrats on a successful first test run!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

Harold_V
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Re: One man's insanity---the story of an induction furnace

Post by Harold_V » Thu Feb 01, 2018 5:05 am

Back to the induction furnace. I had hoped to just ignore the rusting, cleaning up the unit such that it would be functional, but I just couldn't mentally overcome the extensive rust, which was severe in some areas, where water pooled and was slow to evaporate. Inside the openings for the covers was a good example, and the top covers were downright horrible.

Here's a picture of the unit before it was purchased, which clearly shows the general poor cosmetic condition of the unit.
Induction power supply-resized.jpg
I didn't scrape the portion in which the motor/generator is housed, The paint was sound enough to leave, and was very difficult to scrape, so it was lightly sanded to ensure adhesion of the new paint. It was clear to me that this portion (of the housing) was provided to Ajax by the maker of the motor/generator, and was heavily painted. The other two sections had little paint. The negative of painting over the original paint is that a few deep scratches remain. I made little effort to blend them out, as they don't matter. It's not a piece of furniture.

With all of the enclosures scraped, I turned my attention to the base, which was a totally different matter. It is made of 8" channel, and It didn't scrape easily, so it was taken out of doors where I could use a wire brush and my angle grinder.
DSC00003-resized.jpg
When I was finished with scraping, I then attacked the rust with coarse abrasive cloth, more scraping, and, finally, Naval Jelly. I wanted to kill the rust, so the paint would stick over the long haul. I quickly learned that rusting could be removed to base metal quite effectively by using a three cornered scraper. A little sanding afterwards and the surface was quite acceptable, aside from pitting. The Naval Jelly did an admirable job of removing rust from the pits.

Once treated with Naval Jelly, it was time to mask the machine, then it was taken outside again to be primed and painted. Once done, I turned my attention to the covers, all of which were in bad need of attention, as you can clearly see, with the freshly painted supply in the rear:
DSC00010-resized.jpg
I had to get any painting done while we had dry weather, as it was all done outside the shop. I also had a lot of things related to the yard, garden, shop and house that needed my attention while it was dry, so progress was slowed considerably until wet weather set in again. I managed to get all the covers scraped and treated, then painted. I also sand blasted a large number of fasteners, some of which were unique to the power supply. Once blasted, they were given a black oxide treatment to limit their ability to rust. I managed to get it all done before rain set in, then I turned my attention to re-assembling the power supply. I'll pick up on that in the next post.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

Harold_V
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Re: One man's insanity---the story of an induction furnace

Post by Harold_V » Thu Feb 01, 2018 5:13 am

rrnut-2 wrote:
Mon Jan 29, 2018 11:41 am
Hi Harold,

That's great! The motor runs! Now I have to give you some details on how to construct a cooling system.
Hey, Jim!
Thanks for following my progress.
By all means, when you have time, please do fill me in on a cooling system. I've given it a little thought and have some ideas. Right now I'm thinking of going with a closed system, running distilled water and, maybe, antifreeze. I was thinking along the lines of the type used in RV's, which is much safer.

Loved the story about the 900 kW startup. Makes me feel a little better about my experience.

I'm going to talk about the furnace(s) in the near future, Jim. There's an issue with how each of them attach to the power supply, but I think I have a solution for the one you brought me.

I'm amazed at the basic differences in the coils. Wish I knew who made the one you brought, although just because I'm curious. It won't matter in regards to the required modifications I must do.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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neanderman
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Re: One man's insanity---the story of an induction furnace

Post by neanderman » Sun Feb 04, 2018 3:05 am

And thanks to you for sharing!
Ed

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rrnut-2
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Re: One man's insanity---the story of an induction furnace

Post by rrnut-2 » Sun Feb 04, 2018 5:30 pm

Harold, I believe that furnace was made by Ajax, The induction power supply that it was hooked to was an Ajax and the company tended to buy the parts directly from the OEM.

A closed water system would be good. Just make sure the antifreeze isn't conductive at whatever your furnace voltage is. Same goes with hoses, I learned that the hard way. So if the furnace voltage is 3000volts, then all of the rest of the components need to be able to withstand that...and yes the
liquids are one of the components. Nylabraid hose works good, but you will have to retighen the clamps every so often. And speaking of hose clamps,
make sure the ones that you use around the furnace are completely Stainless Steel. A lot of the worm clamps are SS on the outside, but the worm is
regular steel. This will just ruin your day.

Jim B

John Hasler
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Re: One man's insanity---the story of an induction furnace

Post by John Hasler » Sun Feb 04, 2018 9:02 pm

Jim B writes:

> A lot of the worm clamps are SS on the outside, but the worm is
> regular steel.

I hate those. I'd rather the whole thing was steel if it isn't all SS.

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GlennW
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Re: One man's insanity---the story of an induction furnace

Post by GlennW » Sun Feb 04, 2018 11:04 pm

I've never had a problem with these.

Heavier gauge band than the common automotive clamps.

http://www.aircraftspruce.com/catalog/a ... ey=3009104
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

Harold_V
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Re: One man's insanity---the story of an induction furnace

Post by Harold_V » Mon Feb 05, 2018 2:50 am

rrnut-2 wrote:
Sun Feb 04, 2018 5:30 pm
Harold, I believe that furnace was made by Ajax, The induction power supply that it was hooked to was an Ajax and the company tended to buy the parts directly from the OEM.
If the coil supports and the method of mounting are an indication, yeah, it looks like it's Ajax.

They used two different methods to supply water. With the old unit I'm working on, there's two hoses for each side of the coil. Water is under pressure in one set, and the return is the other. They did this because the coil is a twin, two coils wound in one. I expect it was to shorten the path for the water, but that may not be the case. At any rate, I have to use two leads for each side, whether I use the original furnace, or the one you provided.

I made a decision to restore the original, which I don't regret, but I'm not going to put it in service at this time. As soon as I reassemble it, I'm going to start on the donor that you provided. Power for that furnace, which appears to be a 100 pound coil (mine is a 50), is provided by one set of leads only. Water is provided for each lead, but the coil is tapped in the center, where water connects to a common hose for return. I'll plug the center taps and add two copper manifolds so I can connect the twin leads. I like that the donor has a tilt system and is complete, although in bad need of rebuilding. That takes time, as you know, but it's not a big deal. I've learned a great deal about them in working on the original, and I'll make a post in the future, including a few pictures, to show what is entailed in restoring an old furnace.
A closed water system would be good. Just make sure the antifreeze isn't conductive at whatever your furnace voltage is. Same goes with hoses, I learned that the hard way. So if the furnace voltage is 3000volts, then all of the rest of the components need to be able to withstand that...and yes the liquids are one of the components.
Sigh! Wish I'd have given hoses some thought before I jumped. I made a call to verify that the hose needed would withstand antifreeze, so the guy I talked with (not at Ajax) suggested that I use heater hose (automotive). Took about 75 feet to replace all of it, half of which was quite hard and cracked. Only after it was installed did I consider conductivity and was shocked to find it had relatively low resistance. Much too low to be used, as it would leak to ground, something I'd like to avoid. I'll now have to start over with the hose. By the way, this power supply puts out a maximum of 400 volts, so it's not as bad as larger units. The high frequency transformer offers eight different voltages, down to around 200 volts, if memory serves.
Nylabraid hose works good, but you will have to retighen the clamps every so often.
Not familiar with Nylabraid. Is there a preferred place to buy, or should I just buy from Ajax (who has suddenly become silent---as if they don't want to be involved with this project)?
And speaking of hose clamps, make sure the ones that you use around the furnace are completely Stainless Steel. A lot of the worm clamps are SS on the outside, but the worm is regular steel. This will just ruin your day.
Oh, yeah! I've experienced such clamps. Can't take that risk with an induction unit.

The clamps that came with the unit are in perfect condition, aside from being dirty. Bead blasting restored them to like new condition. I don't know that they had ever been removed. The hoses were fused to the barbs and had to be cut away, with the barbs bead blasted to remove the traces of hose that didn't crumble off by abrading. I have reused them and they appear to hold well. I flushed the entire unit (minus the capacitors, which are new) to remove deposits, and test for leaks. I found none. The high frequency transformer was removed, and given extra attention, as it has poor flow when in good shape, and was almost completely plugged. I talked with the makers and was given some guidance. It appears I dodged a bullet, as the unit sat out of doors for at least two years and went through several freeze/thaw cycles. The original caps had frozen, but they resided in the bottom portion, where they couldn't drain. The transformer was higher, although ported at the top. For what ever reason, it didn't get damaged. The maker said it would "leak like a sieve" if it was damaged. It held 100%.

Thanks for your comments, Jim.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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Re: One man's insanity---the story of an induction furnace

Post by John Hasler » Mon Feb 05, 2018 8:44 am

Harold writes:
> Water is provided for each lead, but the coil is tapped in the center, where water connects to a common hose for return.
> I'll plug the center taps and add two copper manifolds so I can connect the twin leads.

If I understand correctly the coil is designed to have water supplied at each end and exhausted at the center. You intend to plug off the center and run water in one end and out the other. If you do this you will need to increase the flow rate to match what would have been the flow rate out of that center drain. This will probably double the inlet pressure. It will also move the hot spot from the center, as designed, to the exhaust end.

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