what is special about a Phase a Matic idler?

A buisness was closing down next door and they sold me their 20hp Phase a Matic CNC rotary converter for $400.

Their website says their Baldor ilders are specially wound. What is different than any other rotary phase converter?

Normally you can start a load the same size as the coverter right? Phase a Matic says they want the converter 50% bigger.

I want it to start the 15 hp motor on my Rockford planer. Will it hurt anything to give it a try? I know I can add another idler if ness. but it'd be nice if I didn't have to.

depending on the load 2X rpc size is not uncommon. the 15 hp rpc i bought was supposed to have special magnet wire wound in it. there is no shaft sticking out so its a cap start only. the rotor/stator clearance is very tight. i had to sand some surface rust just to get it to turn. i ran said rpc off a 20 kw ben and did run a 15 hp lesson motor withit. it did go but i wouldnt cycle the start to many times as everything was working very hard to fire up. this was also starting a 15/hydraulic set up but never needed hyd pressure until up to full speed.

"Their website says their Baldor ilders are specially wound. What is different than any other rotary phase converter?"

Nearly every commercial RPC manufacturer makes some special claims about its idlers.

Usually, the claims are "high resistance rotor", "low starting current", or similar statements.

In reality, the stator, the stationary portion of the idler, that portion which is connected to the incoming line, is no different than any other three-phase motor.

The "low starting current", or the "high resistance rotor" claims, which really amount to the same claim, is implemented in the rotor, which acts as the secondary winding of a rotating transformer.

In some cases, the rotor may actually be different from those found in a conventional three-phase motor.

However, in quite a few cases, the "high resistance rotor" claim is actually implemented by turning the cast-in shorting bars down a tad, thereby reducing its volume, and, hence, increasing its resistance.

Hypothetically, the manufacturing process may be something like:

1) accept the standard three-phase motor at incoming inspection,

2) check for gross defects in a fixture and return any defectives to manufacturer,

3) disassemble motor and mount rotor in a lathe,

4) turn (face) ends of rotor to remove material, thereby increasing the rotor's resistance,

5) part-off shaft thereby removing the exposed portion of the shaft,

6) reassemble motor,

7) test idler in fixture, and

8) apply nameplate.

Wait.

High resistance rotor, low starting current. Makes sense.

But aren't there some downsides to that approach?
Like a converter that is a less stiff voltage source?

Jim

"But aren't there some downsides to that approach? Like a converter that is a less stiff voltage source?"

Strangely enough, the commercial producers seem to concentrate on what happens between the instant the converter is placed across the line and what happens after the converter is up to speed, and not the dynamic performance of the converter after it has reached steady-state.

OTOH, Fitch, and others, have focused on the dynamic performance, that is, the performance of the converter after it has reached steady-state.

Peter and gpkull,
Thanks for the informative replys!

It doesen't sound like it has much or any advantage over a good home made unit. They sell these for almost $4000!!


The only reason I bought it was the price was right and the location was even better.

I don't need to cycle the planer much and there is no starting pressure on the pump so I will give it a try as is.

dont have to thank me. somewhere in this journey i learned the hard way. electrons do have a behavior pattern. use common cents. there aint no free lunch

It doesen't sound like it has much or any advantage over a good home made unit.

Click to expand...

You're correct, if the home made unit includes a voltage regulator or voltage stabilizer ... most shop built units do not. The Phase-A-Matic CNC PAC, and the ARCO Electric VR (voltage regulated) include this feature. ARCO doesn't offer the voltage stabilizer as a separate option, but PAM does:

http://www.phase-a-matic.com/VoltageStabilizerDescription.htm

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Barry Milton