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

[Dave_C]

I have no real objective in mind at this point, but I want to make castings, just to prove I can.
H

Hum, we must be kindred spirits as I tend to do this as well. After all these years, the wife actually understands that I just need to do it, because I can!

Dave C.

[John Hasler]

You're very lucky to have found someone else willing to suck up the cost of the hazardous waste disposal.

When you redo the high-current connections be sure and toque them to spec. I'd also sparingly apply silicone grease (but keep it away from the contactor contacts).

It's possible that the machine has an internal closed cooling loop to be filled with deionized water and a heat-exchanger to cool that water with externally-supplied water.

[tornitore45]

I needed for my soul.

That is the best justification, ever.

I now climb on my white horse and quote Dante Alighieri from the Divina Commedia Inferno.
(I can' believe I am saying this)

"Fatti non foste a viver come bruti, ma per seguir virtute e canoscenza"

I give a shot to a translation

You were not born to live like savages, but to pursue virtue and knowledge.

[rrnut-2]

When I started at the Foundry, we had mg sets from 75kw to 300 kw. All of them worked and maintained the same, although none of them were vertical. All of these units were gone about 10 years later, some sooner than others, they switched to solid state.

All of the "newer" units had "water savers" and when I get a little more time, I will describe there construction in detail. One of those would be very simple to make. A steel tank, a water level switch, a temperature switch, and a pump. They work by recirculating the water from both the power supply and furnace. Cooling is done by adding cold well water. You would do well to check the mineral content in your water. If it is very high, you will need to filter out as much of the minerals as you can. Having water that conducts very well will cause the fittings to erode away quickly.

We did switch to water towers later on. But that came with any set of problems; pollen, bugs, snakes, frogs. And these were at the minimum 10ft of the ground.

To check for a closed water system in your power supply, you will have a pump and a heat exchanger. This is mostly to keep plumbing from eroding away from electrolysis. Probably more common in the solid state units.

On the MG set, grease gets changed out while it is running. Look for the grease fitting on the end bell and opposite that should be a plug. Remove the plug before you start adding grease and leave the plug out for about 30 minutes after you stop adding grease. You should have a brush inspection port on the generator end of the MG. Open this part and check the condition of the slip rings, they shouldn't be corroded.

In all, your unit should be in good shape as it has been in the heated area of your shop for a long time.

Jim B

[rrnut-2]

I am assuming that the MG is 3600rpm.

All of the ones that we had were.

Jim B

[John Hasler]

Jim B writes:
> On the MG set, grease gets changed out while it is running. Look for the grease fitting on the end bell and opposite that should be a plug.
> Remove the plug before you start adding grease and leave the plug out for about 30 minutes after you stop adding grease.

If it doesn't have that plug grease it *sparingly*. Mechanics often grease motors the way they grease everything else: pump grease until they see it coming out. Unfortunately on many motors excess grease comes out inside the motor.

Also, it's ok for the slip rings to be brown. Here's a relevant document: https://www.mersen.com/uploads/tx_merse ... sen_01.pdf

[rrnut-2]

Brown is ok, green is not.

Too much grease will make the bearings run hot.

Also, does the MG have water cooled end bells? I suspect that due to its size, it does not. If it does, test their integrity before you put power onto the MG.

Jim B

[tetramachine]

Wow, Thats a Power Supply. I bought one of those Chinese Induction Heater setups without a power supply. Recently bought a 48V 25 amp PS, but have issues with the PS. Great story, keep use posted.

[Harold_V]

Response to several comments.
The MG set operates @ 3,550 RPM according to the name plate, which is in excellent condition and easily read.
I see no evidence of an internal pump for cooling, nor is it mentioned in the information I have at my disposal.
The end bells are not water cooled. The only apparent cooling for the MG set is the heat exchanger that surrounds the main body.
Greasing is accomplished by filling cups and tightening fully. Each accepts an ounce of grease. Excess grease is discharged through a short length of pipe, so it does not enter the MG set.

This project will move slowly, as cleaning and scraping the paint and rust is just being done as fill-in. I must spend the bulk of my time working on outside projects, as we have a short dry season here. My goal, right now, is to get it prepared for painting, which I hope to do out of doors so I don't have to erect a temporary paint booth. I have a 6,000 pound lift truck that enables me to move the entire unit outside for painting, which would be far faster than painting it on location. As it has not been wired yet, nothing prevents moving the unit.

Jim, I would be more than interested in anything you can share in the way of cooling this unit. Unfortunately, nothing was included. My well produces only about 6 gallons/minute, so recirculating and cooling will be a requirement. I have a water still, left over from my days of refining precious metals, so I am able to produce distilled water.

I appreciate the interest being shown in this project. I expect I'm going to have to lean on the knowledge of others as I progress, as I am not the least bit familiar with the operation of this type of equipment, although I have seen similar equipment in use.

H

[Patio]

Harold crossed a milestone this past Saturday. We connected power to the Furnace and started the Motor/Generator unit, for the first time. It ran well.
Here is Harold with the power supply section.

[neanderman]

Nice to have a face to connect to the name.

Congratulations! Good heating!

[Harold_V]

My thanks goes out to Patio for his professional guidance in getting this project as far as it is. It has not been easy, as there have been problems that I did not anticipate. One of them was in starting the unit for the first time.

Yeah, it did run well. But it also knocked out a fuse in one leg of the primary side of the service. I didn't notice the bump, but both my wife and Patio did. A slight flicker of the lights, but the unit was well on its way to being spooled up, so it continued to run up to speed, and we let it run for several minutes. Those of you familiar with three phase understand that a three phase motor will operate with one leg out, but it can't start. Once rotating, the other phases will continue to run the motor, but, I expect, at reduced power. Fortunately, all we did was run the motor, with no load.

Only after it had coasted down in speed did we start noticing a lowering of light output. Patio immediately checked the voltage in the shop and found only 69 volts at the receptacles. We called PUD (Public Utility District) and reported low voltage. Patio talked to dispatch and informed them what we had done. A crew of two men showed up about 1-3/4 hours later and found the open disconnect/fuse assembly on the pole about 125 yards from our house. A replacement of the fuse permitted a second firing of the power supply, which it did in grand fashion, with the two PUD employees witnessing the start-up. We were all satisfied that the problem had been addressed appropriately.

As there is no load connected to the output, and I have yet to provide any cooling, we did not excite the generator. My purpose was strictly to see if the unit would operate, so I'd know if I should continue the process of getting it fully operation. For that there is good reason, which I will detail in following posts. I'd like to try to bring the interested readers up to date by starting where I left off last summer. I've been working on the unit as time allowed, and have covered some serious territory.

Thanks for your interest in my project.

H