Static Phase Converter used to start an Idler Motor???

adambomb777 · Jul 21, 2017

I just bought my first lathe to learn on. I have never used a lathe before. The lathe is a Delta 11" and I believe the tag on the motor says it is 1 1/2 hp. That would match what I've read about these lathes. In the cabinet the lathe came with a phase A matic static phase converter PAM-1200hd, horsepower range is 8 to 12. It is too big for my lathe motor. In the manual it has an option 2 where you use: Static Phase Converter used to start an Idler Motor, Idler Motor to power the load motor. Is this a good option? If so, What size motor would you recommend? What size machine motor would it comfortably run? I would like to buy other three phase machines later, but have no idea what power they would require. Any suggestions would be appreciated. Thanks.

Monarchist · Jul 21, 2017

adambomb777 said:
I just bought my first lathe to learn on. I have never used a lathe before. The lathe is a Delta 11" and I believe the tag on the motor says it is 1 1/2 hp. That would match what I've read about these lathes. In the cabinet the lathe came with a phase A matic static phase converter PAM-1200hd, horsepower range is 8 to 12. It is too big for my lathe motor. In the manual it has an option 2 where you use: Static Phase Converter used to start an Idler Motor, Idler Motor to power the load motor. Is this a good option? If so, What size motor would you recommend? What size machine motor would it comfortably run? I would like to buy other three phase machines later, but have no idea what power they would require. Any suggestions would be appreciated. Thanks.

Start hunting a 10 HP 3-Phase motor to use as an idler.

Meanwhile, get the hookup info for the RPC from the maker. RPC's can run more (close to 1:1 if loads are only average) than they can comfortably start (50% or more "extra" wanted, idler size vs load motor). Stagger-start, you can run several machines at once, usually. Sometimes one has to power-up a small/medium machine or two, run them no-load, to help the idler start a larger machine.

Read, heed, double-check. Take care not to get cocky and electrocute yerself.

Not a great deal of mystery to an RPC.

adambomb777 · Jul 21, 2017

Ok I have the instruction manual for the static phase converter, http://www.phase-a-matic.com/PDF/SIS.pdf. It looked fairly simple to hook it up to the idler motor. I just didn't know if this was a good route for future equipment and cost effective. Would you buy the idler motor new or look for a used one?

adambomb777 · Jul 21, 2017

I downloaded the pdf instruction manual for the static phase converter. The option to hook up to static phase converter to an idler motor is in there. It doesn't look to hard. I was just concerned if It was a good option for future machines and cost effective. Is there any advantage/disadvantage between the setup I am considering versus buying a rotary phase converter from the big companies?

Larry Dickman · Jul 21, 2017

A few years back I had several machines in my garage. I had a 10hp lathe, so I used it's main motor as an idler with a static converter, then ran everything else off that. Everything worked great.

Chip Chester · Jul 21, 2017

I think those static phase converters have components that are switched out of circuit by a relay once the motor is started. I believe if mis-sized, that switching doesn't occur, damaging either motor or converter. You may be able to change that switching point by modifying the converter instead of adding lots of load to it. Does that mean I know how to make that happen? Nope. But someone here, or at Phase-a-matic might. Not sure the factory will share what they know, but if you can find schematics, they might tell the tale. If I knew where you were with any more specificity than 'usa' I might be convinced to find and lend 1.5 HP static phase converter to let you do a side-by-side comparison.

Chip

JST · Jul 21, 2017

The start circuit for the typical RPC is essentially a static converter. static is just a more expensive way to buy the components.

Since the "converter" has start capacitors, plus a voltage sensitive relay, you can likely change the capacitors and use it with a smaller motor.

Usually the idler is about 1.5 to2 times the HP of the largest load motor. You should be able to use the static to start anything up to its rating by changing the start cap value. Usually they are a start capacitor, a voltage relay, and a box. Some include a run capacitor, which ends up being the balance capacitor, but may also need changed.

Essentially you are getting a free box and relay, just change capacitors to suit the idler you use.

Monarchist · Jul 21, 2017

adambomb777 said:
I downloaded the pdf instruction manual for the static phase converter. The option to hook up to static phase converter to an idler motor is in there. It doesn't look to hard. I was just concerned if It was a good option for future machines and cost effective. Is there any advantage/disadvantage between the setup I am considering versus buying a rotary phase converter from the big companies?

Phase A Matic is a long-time "player" in both static and rotary phase conversion.

Phase Craft is another. One-man Company and a PM member in (at least) the second case.
Helpful, too.

So long as one can get those .pdf's and other help, there isn't any need to find a 'big' company. They all use common, stock, parts.

adambomb777 · Jul 22, 2017

Thanks for the information and suggestions. I will definitely look into these options.

JST · Jul 22, 2017

Monarchist said:
Phase A Matic is a long-time "player" in both static and rotary phase conversion.

Phase Craft is another. One-man Company and a PM member in (at least) the second case.
Helpful, too.

So long as one can get those .pdf's and other help, there isn't any need to find a 'big' company. They all use common, stock, parts.

There IS one advantage to a larger and technically savvy company. There are several basic motor designs, some of which are better for use as a idler than others. If you choose your own motor from the junkyard or wherever, you get whatever you find, and not necessarily the best performing type.

If you buy the complete unit made by a good company (new or used), you will get the optimum type motor, because the company buys enough motors to specify what they want.

rj1939 · Jul 23, 2017

I use a static phase converter to start my slave motor, just a mechanical switch to disconnect the "generating leg" once the slave motor is running. Simple as can be and has served me well.

If you are not going to be with it all the time, a cutout of some sort, would be a good idea, in case of a power interruption (slave motor unable to start properly and burning up)

adambomb777 · Aug 4, 2017

I found an idler motor to use off an air compressor I am buying. I will eventually try to find a setup to power the air compressor at a later time. My question is on the single pole and three pole switches. When I search the internet for the switches it comes up with a light switch type design. Is that what I'm looking for? Also would 30 amp switches be the correct size, since that is more than the max amps on the idler motor? If I understand the directions correctly, it would be a 60 amp breaker and 6 on the wire size. Any suggestions on the best way to do this setup are appreciated.

HOMESTEAD · Aug 4, 2017

The type of switch you want is typically referred to as a "motor starter." Some use a magnetic coil to pull the electrical contacts together when you hit start, some are just mechanical and the action of your finger pushing the start button latches the contacts.

The important thing is this type of switch has an overload limiting device that will protect the motor from overheating. A light switch will not have this and is not a good choice for controlling a motor, despite the fact that millions of motors wired up by Bubbas all across America use them.

HOMESTEAD · Aug 4, 2017

eBay has lots of used motor starters for reasonable prices if you keep an eye out. Allen Bradley and Square D are some good brands to search for.

Ohio Mike · Aug 4, 2017

Starting a 3 phase motor and/or RPC idler is easy. Ideally that you want the PRC legs to be balanced which requires properly sized run capacitors.

JST · Aug 4, 2017

Ohio Mike said:
Starting a 3 phase motor and/or RPC idler is easy. Ideally that you want the PRC legs to be balanced which requires properly sized run capacitors.

Some commercial makers of RPCs get special motors made, which are of the better types for making RPCs, AND may even have the generated leg wound to compensate for the low voltage that a standard motor has to produce. No balance capacitors needed.

Balance (compensating) capacitors are essentially a workaround for the inherently lower voltage that a standard motor will produce when used as an RPC. A purpose designed idler can do without them.

adambomb777 · Aug 5, 2017

HOMESTEAD said:
eBay has lots of used motor starters for reasonable prices if you keep an eye out. Allen Bradley and Square D are some good brands to search for.

Thanks for the information to get me on the right track.

adambomb777 · Aug 5, 2017

JST said:
Some commercial makers of RPCs get special motors made, which are of the better types for making RPCs, AND may even have the generated leg wound to compensate for the low voltage that a standard motor has to produce. No balance capacitors needed.

Balance (compensating) capacitors are essentially a workaround for the inherently lower voltage that a standard motor will produce when used as an RPC. A purpose designed idler can do without them.

Sometimes I wonder if its not best to buy a rpc. I have had no luck finding a 20 or 25 hp motor(to try and build a rpc), to eventually run a 10hp air compressor. When I do find one, they are over half the price of a brand new rpc. I was trying to use what i had until I come across a good deal on a motor or save enough money to buy one. I would like to use the lathe I bought one of these days.

JST · Aug 5, 2017

One made from a motor you can find will work fine.

One purchased complete from a good company will work too, maybe a bit better.

BOTH will make 3 phase and run machines.

Ohio Mike · Aug 5, 2017

JST said:
Some commercial makers of RPCs get special motors made, which are of the better types for making RPCs, AND may even have the generated leg wound to compensate for the low voltage that a standard motor has to produce. No balance capacitors needed.

Balance (compensating) capacitors are essentially a workaround for the inherently lower voltage that a standard motor will produce when used as an RPC. A purpose designed idler can do without them.

Good point and it actually goes along with my thought which wasn't well articulated at all. Its easy to start an idler but that doesn't make it a well balanced RPC.

adambomb777 said:
Sometimes I wonder if its not best to buy a rpc.

Certainly, its easy for some of the guys here say they can build one just a good (and some certainly could) but if you're American Rotary and you're cranking them out by the truck load you're going to learn a few things about making a good RPC.

Static Phase Converter used to start an Idler Motor???

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