Furnace build thread

[Lawrence Duckworth]

Right now the control panel is just setting on the transformer, i need to get hold of Steve stadelman and see if he can walk me through the wiring. Star electric here in Atlanta made the box up.....

[Pete VanderLaan]

It seems like a tight space. Making those turns from the relays to the SCR can be really hard. I think going to see Brian would be a reasonable idea.

[David Russell]

i doubt this is of any help but if you would like to check out the wiring on my 200# stadelmelter you are more than welcome, i am 3.5 hours from the ATL...............

[Lawrence Duckworth]

David......thank you! I would love to.

I'll pm tonight.


The One thumb typer

[Pete VanderLaan]

The trouble with the wire between the relays and the SCR are that you don't want them in either tension or compression. In the longer run that will give you trouble. I used #4 on mine which is for the 150 AMP relays. Getting the bends right is the key. It takes some space.

I believe that Rollin changed the outbound wires from the transformer to coming out of the side instead of the top. They would run somewhat cooler that way if you can do it. Do put the fan on the transformer. While it doesn't need it so much, it makes the big cables to the element banks a lot happier to be cooled.

[Greg Vriethoff]

Originally Posted by Pete VanderLaan

...they asked Miller for a welder that would perform continuous duty. Miller said "sure" and supplied them with a unit that supplied continuous duty- for an eight hour work shift.

Another thing to thank those evil, corrupt unions for.

[Rollin Karg]

Originally Posted by Pete VanderLaan

I believe that Rollin changed the outbound wires from the transformer to coming out of the side instead of the top. They would run somewhat cooler that way if you can do it. Do put the fan on the transformer. While it doesn't need it so much, it makes the big cables to the element banks a lot happier to be cooled.

Mine come in the side of the Transformer and out the bottom. The Transformer is mounted about five feet off the floor. The box with the SCR and kill switch is mounted on the side of the Transformer. I don't use welding cable and I know Steve did, but I'm not sure why. I found his thinking on the electrical end to be pretty good but I've not gotten the thinking on the welding cable.

[Rick Sherbert]

Hey Rollin,

What size and kind of wire are you using and how much current are you pulling through each?

Thanks

[Rollin Karg]

Originally Posted by Rick Sherbert

Hey Rollin,What size and kind of wire are you using and how much current are you pulling through each?
Thanks

Rick, my furnaces are three phase, 208 volt and each has it’s own 125 amp breaker. We ran 2/0 copper wire. It’s been awhile since we set this up. I think originally they were pulling something in the 90 to 100 amps range. I think I dialed it back with the current limiter just because all those amps made me a little nervous. We eventually got them running smooth and I went on to other things, so I never went back and rethought the amp settings.

I find myself a little reluctant to post this info. I went to the handbook to size the wire and then had my Electricians figure it too just to be sure. If you’re thinking of wiring a furnace you should also rely on the handbook and not what I’ve done.

[Pete VanderLaan]

My Moly is under a 125 AMP breaker as well and I too used #2 wire for the hookup. I used some #4 in the panel with the SCR and the relays. I got to the 125 breaker factoring a 1.25 safety factor. I recall I was pulling about 93-94 AMP. All the wiring from the transformer to the element banks is 350mm stranded annealed copper.

[Rick Sherbert]

Thanks guys. My furnace will also be 3 phase 208 and it's 300#. I will size it via load tables but just wanted to hear about an alternative to the welding cable.

[Pete VanderLaan]

Just keep the cable ends cool and they will be fine.

[Rollin Karg]

Originally Posted by Pete VanderLaan

Just keep the cable ends cool and they will be fine.

That's the sweet part of using bars on the top, your cable stays away from the heat.

[Lawrence Duckworth]

Here’s a drawing of the control panel Star electric/Georgia Furnace made up for me. I emailed this to Steve S. and he said it looks ok, so if anyone wants it let me know and I’ll email it to you too.

In one of the photos of David Russell’s transformer, I noticed what looks like a grounded leg. If thats what I’m really seeing there, can someone explain why that leg would be grounded?

btw.....the consensus is that the 65 amp. contactor is too small for the 62 amps this thing should draw.......so i'm gonna trade it out for an eighty amp

[Pete VanderLaan]

I put the Noalox behind the bussblock connections to the taps Lawrence. I did have trouble with one of those blocks melting since it was not tightened enough. Take note that molten aluminum could wind up down in your windings. An 80 AMP relay would cover the 1.25 service factor multiplier quite well. I recommend putting a small blower on the taps to cool them. While the transformer is fine with the 150C temp rise, the cables aren't.

[Steve Stadelman]

[quote=Lawrence Duckworth;98650]In one of the photos of David Russell’s transformer, I noticed what looks like a grounded leg. If thats what I’m really seeing there, can someone explain why that leg would be grounded?

One or the other leg of the transformer will be grounded to provide a ground reference, otherwise the system will function like an isolation transformer. Isolation transformers are not bad at all but if you do not ground diagnosing electrical problems is difficult because you have bo reference and all readings except the ones between the two transformer outs will be spurious.

Any electrical inspector except one who is familiar with flammable atmosphere wiring schemes (hospital operating rooms) will be very uncomfortable without it grounded.

[Lawrence Duckworth]

Thanks Steve.
I’d be curious to hear what you guys think of using a copper cable crimp connections rather than the aluminum blocks. The guy that had the local welding supply house made up our replacement welding leads for the gas welders (00 cable) with a neat little crimp tool that fastened the big copper connector to the cable ends,…seems like the copper would be a better connection. What’s the reason you guys don’t use them? ... [yes. I’ve tried to make sure and lube every aluminum electrical connection inside and out with the nolox].


Here’s the latest progress pic…
Used #2 copper wire to power the control panel and also to the transformer. The 0000 cable goes through the side of the transformer and out the other side of the wall to the furnace. I want to cut a hole in the top of the transformer cabinet and mount a small squirrel cage type blower to help cool stuff off. Also, the table is a permanent part of the electrical layout (made it ez’r on the back and knees)

oh yeah...I jobbed out the pannel to Georgia Furnace for $1,600.00 bucks

[Pete VanderLaan]

When we tried the copper crimp connectors, they failed quickly.

I had one of the aluminum blocks fail on my furnace and my electrician convinced me to let him install the copper crimped connector. It's been there for two years so far. He said the key to using them is the amount of torque used to crimp it. They used two, 3' cheaters to crimp with. Seemed crazy at the time, but it still works. Not a recommendation, just fyi.

[Pete VanderLaan]

That could certainly be the case. When Steve and I first used the copper crimp, we didn't have that kind of tooling available to crimp it. The positiv pressure from the allen bolt lug has worked for me. If the aluminum fails, it wasn't tightened enough in the first place. I would agree there should be a better way.

[Lawrence Duckworth]

Im pretty good at tigging copper to copper

[Pete VanderLaan]

Good. All that's left now is recreating the Portland Vase and you're done.

[Lawrence Duckworth]

Originally Posted by Pete VanderLa[LIST

[/list]an;98718]All that's left now is recreating the Portland Vase and you're done.

Not a problem.....howz the RE-PETE" Coffee table book coming along.

[Rollin Karg]

We've done it both ways. If done correctly and the connection is kept cool they both work.

[Lawrence Duckworth]

Here are some Kiln progress photos.


.....a special thanks to David Russell, Dane and Scott Gamble....great forum!