This Amp/Volt thing :confused

[Oldiron2]

Originally Posted by Seafarer12

I doubt he can get all the things required for free. You have to find 2 5hp motors one being three phase. Then all the stuff to make a frame and coupling. Then you may or may not have good balanced voltage. You run a 3 phase motor imbalanced long enough it will fail. Last time I looked at what bridgeport mill went for 250 isnt much. He would also have the option of using the VFD in the future if needed.

My Bridgeport runs off a single, old, heavy, 3-phase "idler" motor (forget the HP rating; probably 3, maybe 5) with a capacitor between two windings. Just one motor, no frame, no coupling, nothing fancy. I've known a half dozen fellows running such units and none has ever had any problems I heard about.The input current on mine has been checked a number of times, both while idling and while running under decent load, and has always been within wanted specs. Yes, if I ran this machine all day with a large hogging endmill doing production work, maybe that wouldn't be good enough and I'd eventually have problems, but as I stated earlier, most home shop users don't do that kind of work and I doubt the OP does either.
As for the first point, in many places such motors can be gotten free if one just does a bit of looking. Obviously harder if someone lives in the middle of the woods and never goes to town; in a decent sized town, things are generally different. I've even seen a Bridgeport go for free once. I consider $250 to be more than loose change and worth keeping if I have a cheaper alternative that works.

[lamename]

Originally Posted by nvreloader

DSW

IF,? I understand this amp thing, I CANNOT run the Miller 211 on the 50a line (set up for the AC/DC Thunderbolt) welder?? Too many amps and I'll let out the magic smoke and crispy critter it, Correct?

Tia,
Don

Sounds like the op should stick to running the machines and not trying to hook them up or modifying them. That could get ugly.

[Timster2]

Regardless of the wire size you are currently considering plan for the future. If you are closing up the walls and running conduit inside the walls going larger and or multiple runs at this time is a lot cheaper than re running conduit in the future. The cost is minimal to up-size the conduit. And remember there are limits as to the size and quantity of wires in given conduit size. Lots of things to consider other than just wire size. You need room for ground conductors as well. Best to have your sparky friend drop by to "inspect" your progress prior to closing up the walls you will save yourself a lot of work in the long run.

[Seafarer12]

Originally Posted by Oldiron2

My Bridgeport runs off a single, old, heavy, 3-phase "idler" motor (forget the HP rating; probably 3, maybe 5) with a capacitor between two windings. Just one motor, no frame, no coupling, nothing fancy..

I thought we were talking about making a M/G set to make 3 phase to run the mill. Thats why I said the two motors, and extra stuff.

I am curious about your set up. Are you just single phasing a 3 phase motor with the single phase power and a cap to shift the phase angle to make second phase?

[Oldiron2]

Originally Posted by Seafarer12

I thought we were talking about making a M/G set to make 3 phase to run the mill. Thats why I said the two motors, and extra stuff.

I am curious about your set up. Are you just single phasing a 3 phase motor with the single phase power and a cap to shift the phase angle to make second phase?

Yes. The motor acts as a generator to a great degree, producing the third phase. The capacitor improves the phase angle and thereby evens out the current, as I understand it. In any case, it works quite well.

[Seafarer12]

The cap acts as a second phase like a capacitive run single phase motor. It gives you your phase shift to get the motor spinning. It would put a lot of stress on the motor and make a lot of extra heat on the winding doing most of the work. The older motors were built a lot heavier duty than the motors now. I have changed out a few motors after they single phased for a while becuase of bad contactors loosing a phase. They just run hot till the insulation burns and they short out. And that is running two phases at proper phase angle of 120 degrees. With a cap you can't get more than 90 but it is less than that but don't ask me to remember that far back in school. Hey if it works it works.

[lamename]

Originally Posted by Seafarer12

The cap acts as a second phase like a capacitive run single phase motor. It gives you your phase shift to get the motor spinning. It would put a lot of stress on the motor and make a lot of extra heat on the winding doing most of the work. The older motors were built a lot heavier duty than the motors now. I have changed out a few motors after they single phased for a while becuase of bad contactors loosing a phase. They just run hot till the insulation burns and they short out. And that is running two phases at proper phase angle of 120 degrees. With a cap you can't get more than 90 but it is less than that but don't ask me to remember that far back in school. Hey if it works it works.

If it works it works...you sound like me. From my experience the caps just act as a chase leg. I would say the phase angle missing is still 120deg but the caps "trick" the motor to think it has the open phase. No load available though. That's how I see it. Static anyhoo.

BTW Seafarer, read your job description. Sounds like we do alot of the same stuff. I built a remote timed gate control today, and might be changing out a 34.5kv transformer tomorrow. Fun stuff.

[Seafarer12]

Lamename- I saw yours too. You guys take care of it after we make it. We step it up to 138kv and send it out. We are taking it easy this week. We had a major on our big unit after a compressor blade let go and tore up the rest of the compressor. 38 hours OT is nice just not in 8 days. They always contract out the mechanical side but the electrical is always up to us. The thing was getting new blades for 6 weeks but as soon as it got back they wanted it running NOW. Just about like it always is. Good luck with the xformer.

[lamename]

Ouch 38 hrs ot in 8 days!! Uncle sambo will be happy. We are a small utility. I get to farm some stuff out but 99% of the time I'm a 1 man show. Which is good and bad. Usually something different every day. Then I have to write procedures on how to do what I did. I leave out the scratching my head and cussing parts. As I write this I'm doing load studies.

[Oldiron2]

Originally Posted by Oldiron2

My Bridgeport runs off a single, old, heavy, 3-phase "idler" motor (forget the HP rating; probably 3, maybe 5) with a capacitor between two windings. Just one motor, no frame, no coupling, nothing fancy. I've known a half dozen fellows running such units and none has ever had any problems I heard about.The input current on mine has been checked a number of times, both while idling and while running under decent load, and has always been within wanted specs. Yes, if I ran this machine all day with a large hogging endmill doing production work, maybe that wouldn't be good enough and I'd eventually have problems, but as I stated earlier, most home shop users don't do that kind of work and I doubt the OP does either.
As for the first point, in many places such motors can be gotten free if one just does a bit of looking. Obviously harder if someone lives in the middle of the woods and never goes to town; in a decent sized town, things are generally different. I've even seen a Bridgeport go for free once. I consider $250 to be more than loose change and worth keeping if I have a cheaper alternative that works.

Guess what just showed up on Craigslist?



SF bay area craigslist > east bay > for sale / wanted > free stuff


Free 480v three phase turbine motors (concord / pleasant hill / martinez)

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Date: 2012-06-01, 3:27PM PDT
Reply to: v3pxp-3051775466@sale.craigslist.org
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I have some Hormann siren motors, 480v three phase... 6 of them.

I need them gone today.

This is a huge gift to some scrappers. There has to be 50 pounds of copper in each of these things, but I don't have time to deal with them. This is basically a multi-hundred dollar gift to somebody who has the time to recycle them, unlike me.

Please, just come get them.

I won't be checking email, so just come by with your truck and they're yours. First come, first serve.

Here:

xxx Arnold Drive, Suitexxx
Martinez, CA 94553

I'll take this ad down when they're gone.


PostingID: 3051775466

[Seafarer12]

OldIron, Man I would jump on a deal like that.

Lamename, We are good size a few thousand employees with a 2700 mw peak load.