Rotary Phase and Dust Collector

[Mike Wellner]

I am looking at a couple options for my PM 75 dust collector, I'd prefer to find a used single phase motor, but has been impossible so far. My question is would a dust collector on a rotary phase convertor be a soft, medium or hard load? How many amp breaker would I need?

Specs
Voltage: 230/460
Phase: 60 Cycles/3 phase
Amps: 8.2/4.1 amps
RPM: 3450

[Leo Graywacz]

That is a 3HP motor. You should be able to find one somewhere.

[Foras Noir]

Get the frame no. from the motor label. Call Baldor. You will find a 3 HP/1 phase. The amps will be higher than the 3 phase (obviously).

[Darnell Hagen]

Medium, but when it comes to phase convertors, buy bigger than what you need.

[Chip Lindley]

Concerning RPCs, any reputable maker's 5hp unit will run your DC's 3hp motor. My shop uses a 5hp Arco Model A which will run up to 15hp (total) when motors are started one-at-a-time. (each motor not exceeding 5hp)

The Model A uses a 30A breaker and 8-2-G from panel to RPC. I use 10-3-G from RPC to 3ph. machinery.

If you should even remotely contemplate other 3-phase machinery in your shop's future, consider an RPC; much cheaper than changing out bigger motors. 3ph machinery can often be had dirt cheap, since so many shun it for home shops. This bargain status goes out the window when a new single phase motor replaces the original. You will suffer sticker shock fast when you price new commercial-grade motors such as Baldor or Leeson.

RPCs can be rigged to be turned on remotely same as DCs. At the push of a remote fob button you instantly have 3-phase power which gives virtually 100% horsepower of your machine motors.

[Mike Wellner]

Problem is its a custom mount motor, doesn't state a frame size on the label. So I'd have to take a 56C face mount, make an adaptor ring, and thread the shaft, because it takes a 5/8 nut, 18 TPI. I haven't had a chance to take it off and measure the holes of the face mount to see if it would line up with a 56C face mount.

[Peter Quinn]

I added a RPC to the shop last month to power a 5HP shaper, that was considered a medium load. Relatively simple, cost about the same on a single machine all said and done, as changing out the motor for single phase. BUt I got a heck of a deal on the shaper, the RPC powers it as if I had true 3 phase, and now I can get a heck of a deal on another 3 phase machine and I'm ready to go.

Problem with that scenario in a small shop is that the DC is one machine that will be used simultaneously with pretty much every other machine in the shop. So if you wanted to get a RPC to have 3 phase capacity down the line it might have to be sized to handle the DC plus at least one other machine, and that can get expensive.

Like chip said, you can get one to run two or more machines but start one at a time. Al the big three phase industrial stuff where I work requires sequential starting of multi motor machinery anyway. I have seem occasional 3 phase motors for sale cheap, but I haven't seen any decent single phase motors of any size used and cheap. I think its a supply and demand thing.

For what its worth I'm using a Gentec American Rotary phase convertor and I'm quite happy with it. It was easy to instal even for an electrical novice like myself, it came with a magnetic starter wired in the control panel and is powered by a shaft-less Baldor reliance generator motor. Its a soft start unit that runs as quiet as a kitten. In fact its just a bit quieter than small box fan. No affiliation with American Rotary, just a happy customer.

[Tony Shea]

So your phase converters aren't annoyingly loud? Last one that I was around at a granite shop about 5 years ago has this awful hmmm to it that hit some kind of resonance frequency and just jarred my head. It was odd to be around and actually would make you quessy. I'm assuming it was a large unit as it supplied lots of big equipment. Maybe smaller units aren't quite as bad but that experience was enough to shy me away from them.

[Mike Heidrick]

I have a 7.5 ideler motor and a static phase converter running my 5hp single stage Delta. Works perfectly.

[Kirk Poore]

Unless you have other 3 ph motors you're going to run, I'd suggest a VFD. It would almost certainly be cheaper, especially cheaper than buying a commercial RPC. As for circuit size, I think you could use it on a 20 amp 240V single phase circuit, but you'd want to check the documentation of the VFD.

Kirk

[Foras Noir]

All the cut and drill is still a whole bunch easier than a rotary.

I have both large and small VFDs. They are fantastic. Especially because I had factory rep.s do the set up.

Unless you enjoy electric work, and have the time for it, for a single motor - do the adapter plate.

[Mike Wellner]

I thought about the VFD route, but would I have a problem with voltage drop as long as I use a heavier gauge cord so I can move it around?

I think this is the best option. I just need a enclosure at $100.00 and then a VFD at $150.00.

[Mike Wellner]

I dont think a 3 HP VFD would be sufficient for that dust collect as it should be at least 3/4th of the horsepower. So 5hp VFDs are more common, but it seems like another expensive option to me, $250 to $300 for a VFD and $100 for a enclosure.

[Kirk Poore]

I dont think a 3 HP VFD would be sufficient for that dust collect as it should be at least 3/4th of the horsepower. So 5hp VFDs are more common, but it seems like another expensive option to me, $250 to $300 for a VFD and $100 for a enclosure.

Well, this one (http://www.factorymation.com/s.nl/it.A/id.198/.f) puts out 10.8 amps at 230v, so it will cover your current motor, and it's $185 plus shipping. I'm not sure what your enclosure needs actually are, but I'd think your $100 estimate is at the high end (you might get a better deal on flea bay or a used electrical equipment place). I don't see voltage drop being significant, unless you're using a 100 ft extension cord.

I do have a RPC feeding a three phase panel, so I can see going that way too. But the main advantage is when you have multiple machines, and you'll need to have the RPC sized to handle both your largest machine and the DC at the same time. And you'll need overload protection on your DC, unless it's already got it.


Kirk

[Mike Wellner]

Well, this one (http://www.factorymation.com/s.nl/it.A/id.198/.f) puts out 10.8 amps at 230v, so it will cover your current motor, and it's $185 plus shipping. I'm not sure what your enclosure needs actually are, but I'd think your $100 estimate is at the high end (you might get a better deal on flea bay or a used electrical equipment place). I don't see voltage drop being significant, unless you're using a 100 ft extension cord.

I do have a RPC feeding a three phase panel, so I can see going that way too. But the main advantage is when you have multiple machines, and you'll need to have the RPC sized to handle both your largest machine and the DC at the same time. And you'll need overload protection on your DC, unless it's already got it.




Kirk

If I do that way, 12/3 wire is what I want right, on a 20 amp breaker?