Monarch EE Run on a Phase perfect?

I have read that one of the tricks Monarch had to run their lathes at consistent speed under difficult loads was some fancy switching in the direct drive system.
Will a Phase Perfect or other digital phase converter destroy the electrics?
I've seen some Wave patterns of the PP converters as compared to the Rotary converters and the PP ones are really rough while the rotary models can be tuned to deliver a flawless three phases.

Supplying your Monarch EE from a Phase Perfect will not hurt it. PP converters are not cheap crap bang-bang controllers.

Two of the three legs on a PP output come directly from the utility supply. The third, generated, leg is pretty low in harmonic distortion (for a power supply, not for gourmet audio). Manufacturer claims voltage balance between legs is within 1%, and total harmonic distortion is under 3.5%. Incoming noise from the utility lines is frequently of that order.

Care to share the source of the wave patterns you were looking at that have you so worried?

If you are talking fancy switching, you must be talking about a tube machine, not a motor-generator machine. If so, unless you are talking about the rare very-last generation 10EE, then you only need (or can even use) single phase except for the coolant pump, so a PhasePerfect would be a waste of money.

Beware that a PhasePerfect passes two utility legs straight through, so only the third, generated leg has any magic applied. In that regard, a PhasePerfect is a lot like an RPC, but the “wild” leg is tame.


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The PP produces an output that is as good as a sine for a motor. I think some older ones had less "sine filtering" than newer ones, so the ragged waveforms are probably an old issue not so true now.

In any case, the resultant of the output as the motor sees it, is essentially "perfect" within a couple percent, which is better than the powerco provides.

But, yes, if you look at the circuit for the 10EE, the tube one at least uses only single phase for the spindle power. The pump might work fine off a "static converter", bad as they are.

Raul McCai said:

I have read that one of the tricks Monarch had to run their lathes at consistent speed under difficult loads was some fancy switching in the direct drive system.
Will a Phase Perfect or other digital phase converter destroy the electrics?
I've seen some Wave patterns of the PP converters as compared to the Rotary converters and the PP ones are really rough while the rotary models can be tuned to deliver a flawless three phases.

Click to expand...

Dunno what you've been reading, but... no, a Phase-Perfect won't harm it.

DoD / Big Corp third-party "upgrades" aside, there were only ever two "eras" of factory 10EE that could even USE 3-Phase for the "drive system".

- The last-generation "Monarch Sidney" with a true 3-Phase-ONLY Solid state DC Drive. Many, if not most, third-party rebuilds "back in the day" used one or another 3-P only Solid State drive also.

- The early "Motor Generator" units with a 3-Phase motor driving a pair of DC generators (one each, Armature and one-each Field supply, plus source for control relays & contactors) expected 3-Phase power.

- The early-early and serious rare always, even more-so NOW, "Sundstrand" hydraulic final-drive had a 3-P pump motor, but did not HAVE to have. A 1-P would do the do if you could fit it in. The hydraulics cleaned up its act.

- WiaD and Modular "hollow state" tube drives were inherently single-phase critters. ONLY. 13EE / 1000EE were 3-Phase, tube or solid-state.

AFAIK, 100% of 10EE shipped with 3-Phase coolant pumps. Easy way forward is a new pump, single-phase @ approx $80-$120.

There was no "fancy switching". There was rather basic, and bog-standard compensation for stability under load, plus "the usual suspects" of that era for Field-loss protection and safe braking/accel & decell operation.

The only thing "fancy" Monarch did was to provide for operating their DC motors at higher Armature voltages than "nameplate" so as to provide better reserve for stabilizing RPM when in the "Field Weakened" zone. Tough act to follow for the unaware, otherwise not hard. A "nameplate" - DC variable-speed motors especially - is but one snapshot on a curve anyway, so a nominal 230 VDC motor didn't mind the odd excursion to 250-270 VDC.

Spikes at 4 to 5 times peak operating DC voltages where contactor-controlled starting, braking, reversing were involved could surely put a hurt on "merely" 700-1200 PIV SCR bridges or Thyratron substitutes, though! Evidence right here on PM! "4Q" or "regenerative drives, such as 514C-XX Eurotherm/Parker-SSD, less of an issue. They don't have contactors. They don't generate such spikes to begin with. They ARE armoured to deal with them, even so. A $70 MOV is not your Dad's one-dollah Radio-Shack item.

"Dangers?" I'd not recommend running the ancient 3-Phase motor of an MG 10EE off a VFD. Fair risk of fluting its bearings even if the old winding wire and insulation stand up to it.

OTOH it is happy as a clam with a 7.5 HP or better idlered RPC anyway. Any dodginess in the "generated" leg dasn't onpass its weakness through the DC conversion process and its high inertia - electrical as well as mechanical - that sits in between input power source and final-drive Dee Cee motor.

A Phase-Perfect is fine, but "overkill" for an MG-era 10EE.

Unless ....you also have other, potentially more critical, work for it (I do not) and/or a concern to pass less THD back up the local line to annoy your own household 'tronics and immediate neighbours as an RPC does, and cannot avoid. Basic nature of the beast, unwelcome, a concern I DO happen to have, hence TWO Phase-Perfect here and only one RPC.

HTH.

"Voodoo " in 10EE has been overstated for Donkey's Years. As things electrical or electronic go, they are actually brute-simple, anvil-class durable, and NOT all that hard to maintain.

Compare a 10EE's modest electricals to ANY modern CNC, for example.

"Voodoo " in 10EE has been overstated ...

These days any hollow state electronics is a half step away from full voodoo.



We had one years ago at work, and it kept the electronics techs in fits keeping it running.