1942 10EE No-Tubes and VFD Question

Hello! I have a 1942 10EE. It does not have tubes. It has an old 13.2 amp, 3-phase AC motor that runs an exciter that runs the DC motor. It appears to be all original and if not, it is still old! I was running the lathe with a phase converter, but it blew a capacitor (lathe was not turned on at the time). Is there any reason I cannot provide 3-phase 220V to the lathe with a VFD on 60hz? Will that motor have any idea that it is getting something else sending it 3 phase other than the converter?

Thank you!

Andy

The motor is not rated for VFD use and may or may not give you problems. Replacing that cap is much cheaper than a VFD.

CreeCustomGuns said:

Hello! I have a 1942 10EE. It does not have tubes. It has an old 13.2 amp, 3-phase AC motor that runs an exciter that runs the DC motor. It appears to be all original and if not, it is still old! I was running the lathe with a phase converter, but it blew a capacitor (lathe was not turned on at the time). Is there any reason I cannot provide 3-phase 220V to the lathe with a VFD on 60hz? Will that motor have any idea that it is getting something else sending it 3 phase other than the converter?

Thank you!

Andy

Click to expand...

What labeeman said. In order of "quality"?

Utility mains 3-P, Generator set 3-P, Phase-Perfect 3-P, Decent RPC 3-P.

All of which are a nice, smooth, clean, slow-moving, 60 Hz pure sine wave.

Anything less? Money will start going into the lathe as well as wotever powers it.

Fix your RPC. Or replace it.

Put the VFD onto a 3-P motor with "inverter duty" right on its label, ELSE peddle it.

VFD capacitor banks have finite, and rather SHORT lives, even in storage. No point in stashing them in your wine cellar. They degrade with age rather than improve.

Thank you gentlemen! I think my phase converter motor was damaged as well. Looks like I will replace the whole system.

CreeCustomGuns said:

Thank you gentlemen! I think my phase converter motor was damaged as well. Looks like I will replace the whole system.

Click to expand...

Have the motor checked. Serious hard to harm one.

Might just as well be the RPC's start switch, contactor, potential relay, or time-delay relay as well as capacitors, rather than the idler motor.

The only electric device ever crafted by the hand of man as is as simple and durable as a 3-P induction motor might be an ignorant electric strip heater.

Even so, I'd bet on the motor outlasting a heater, if only because no one ever much gave a damn about keeping the heater clean of rocks, dog hair, spider shit, and mouse-piss, and most folk with the motor will at least kick the birdshit off it and grease or replace the bearings every 40 years or so.

I will, thank you!

I've been considering doing the same thing and running the lathe's native 3 ph motor with a VFD....brain dead simple mod and can leave all the oem stuff there if wanted and easily include the safety feature with the f/r drum switch that prevents the vfd/motor from firing up unless the switch is the off position. Other than that safety there is no interaction with the controls for the lathe.

Comments are right that clearly the original motor is not inverter duty rated as would be appropriate for a vfd. It is kind a roll of the dice. I understand the largest thing that makes a motor inverter rated is the "level" of the insulation. VFD/Inverters can introduce voltage peaks / spikes that can cause questionable insulation to fail.

I'm gonna chant with an EE about this, but I'm thinking in "gentle" variable speed service the voltage spikes may be minimal compared to hard accelerations and decelerations and frequent speed changes that a rated motor would be exposed to.


Now to further tempt the issue one can acquired a 5 hp VFD for slightly north of $100.

4KW 22V 5HP VFD SINGLE PHASE VARIABLE SPEED DRIVE INVERTER VARIABLE FREQUENCY | eBay

I know the drive is cheap Chinese questionable quality stuff.....but if you get 5 years out of it.....they will be $50 by then.

I'm about crazy enough to try this as I hear no one has done it yet.

rakort said:

I'm about crazy enough to try this as I hear no one has done it yet.

Click to expand...

How to argue THAT?

I'm not inclined to argue the point. Too bad I cannot sell tickets, but wot the hey..

How 'bout I hold yer beer?

Many solutions.

Here's my two-cents' worth:

I ran my '42 motor-generator off a homemade RPC for many years, and patched it up each time it needed 'help'. It spent many, many years in a government facility and it's original contactors and wiring had seen much, much better days. Whilst nursing it along, I gathered up some various goodies and evenutally converted it to full VFD, on a very minimal budget.

My homemade phase converter works just fine, but now I have it in a portable chassis (forklift or end loader to lift and carry, but it's on wheels to roll around the shop). I use it to test 3ph motors and machines, but all my tools run single phase into VFDs.

Simple fact: The Monarch 10EE motor-generator system will run that spindle without 3phase power. It'll actually run that spindle with NO ELECTRICITY... if you steal the gas engine off your roto-tiller and spin that motor-generator, the spindle will power up and run wonderfully... you'll just have a very loud and stinky shop.

That being said, it doesn't matter if you make the 3phase motor run on single using any of the other methods shown in the STICKYs (Steelman, or Peter Hass's methods)... or use a VFD to spin the motor, or a square-wave inverter... or even burn firewood to spin an old diesel supercharger belted to the thing (actually... that's a pretty neat idea- hold my beer!) It will run, and it'll cut just fine, because the motor/generator's OUTPUT is what runs the spindle motor.

SO... that being said... Here's what comprises my machine's 'new' drive:

An old Allis-Chalmers 7.5hp compressor motor, 480v 1800rpm, with damaged shaft.
An old Allen-Bradley 1336 (very early) 10hp VFD, 480v input.
An 8" 120v cooling fan robbed from the carcass of some old mainframe computer (probably ENIAC's younger brother)
a 480-240/120v 5kva dry transformer, liberated from the wreckage of an old billboard sign somewhere
A Gates Polychain toothed-belt.
Two sheaves (one about 8" diameter, one about 3") to fit said belt.
A surplus 50-ohm resistor bank from an elevator dynamic brake system (about 2kw of dissipation capacity, iirc)
A steel plate, and some bolts...
Some surplus #30 chain and two sprockets, probably from Surplus Center
a 10k linear-taper Bourns poteniometer (the common industrial/mil-spec type) from my radio stuff junk box.

I removed the DC motor, gearbox, motor-generator assembly, all the controls, etc, from the machine, but not before boring the large sheave to fit on the backend of the spindle (where the original 10EE's belt went *mine was a flat-belter, with the backgear box's integral belt-oiler feature). I also re-cut the Allis motor's shaft true, and bored the small sheave to fit.

I knocked the cooling fan blades off the Allis motor, mounted the 120v cooling fan to it's shroud instead. No, it's not an inverter-duty motor... so what? I put in new bearings, and made new vent screens to keep mice out.

I mounted the transformer and VFD into the apron where the MG USED to be.

I mounted the 10k pot, with sprocket 'n stuff, in place of the original two-section poteniometer.

I wired the power control contactor from my line cord (240v/20A) to the SECONDARY (240v) side of the transformer. I wired the cooling fan from one 240v leg, to the center-tap of the 240v secondary wiring (for 120v power to fan whenever unit is on). Connected the 480v PRIMARY of the transformer to L1 and L3 of the VFD. Left L2 unconnected.

Connected the VFD's A-B-C output to the Allis motor.

Connected the dynamic brake output to the resistor, which I mounted on the back of the apron.

I programmed the motor max frequency for around 200hz or so, mebbie 210, I don't recall.

Hold my beer... I'm cutting metal. It's beastly strong, and smooth... will easily tear my arms off if I'm ignorant enough to let it, but gentle enough to put threads into a 1/4" pine dowel rod.

And it's quiet. I don't mind hearing a cutting tool digging into innocent metal, but I like listening to music whilst I work. As much as I like loud music, regardless if it's a symphony or a Ted Nugent concert, I prefer it by choice, not necessity... and with this setup, I got it.

rakort said:

I'm gonna chant with an EE about this, but I'm thinking in "gentle" variable speed service the voltage spikes may be minimal compared to hard accelerations and decelerations and frequent speed changes that a rated motor would be exposed to.

Click to expand...

It's not a function of load and effort which identify the 'spikes'... it's the fact that the inverter is switching into an inductive load, and the end result is noise that exists in the high frequency/high voltage realm. Changing the load does NOT make it better. Reality is this- you're operating a winding at 480v, the insulation may be good for 600v, but the noise (harmonics into the HF range) induces voltages in very slight current, but in excess of 1000v. End result is insulation breakdown.

How serious is it? Depends on the motor... if it's a serious duty, US-made electric motor from the 50's through 70's, it'll likely be much better than you think... most of the motors I've worked with in this vintage survive insulation testing with no leakage in excess of 1kv, and I've not killed a single one of them. A lousy motor, though, might be rated for 230v, and not pass at 500v. Feed it a 1kv RF signal, and it'll be shorted in a few minutes.

The other issue with VFD operation is cooling. A motor with integral cooling fan, running at full torque and zero speed, has no airflow... it's totally convection cooled. If the amount of generated heat exceeds that which can be disspiated, it'll cook. I yank the motor-end fans and mount fixed speed fans on all mine... even the machines I expect to run at a reasonable speed, because when you overspeed them (beyond 60hz) they become air-raid sirens right quick.

DaveKamp said:

It's not a function of load and effort which identify the 'spikes'... it's the fact that the inverter is switching into an inductive load, and the end result is noise that exists in the high frequency/high voltage realm. Changing the load does NOT make it better. Reality is this- you're operating a winding at 480v, the insulation may be good for 600v, but the noise (harmonics into the HF range) induces voltages in very slight current, but in excess of 1000v. End result is insulation breakdown.

How serious is it? Depends on the motor... if it's a serious duty, US-made electric motor from the 50's through 70's, it'll likely be much better than you think... most of the motors I've worked with in this vintage survive insulation testing with no leakage in excess of 1kv, and I've not killed a single one of them. A lousy motor, though, might be rated for 230v, and not pass at 500v. Feed it a 1kv RF signal, and it'll be shorted in a few minutes.

The other issue with VFD operation is cooling. A motor with integral cooling fan, running at full torque and zero speed, has no airflow... it's totally convection cooled. If the amount of generated heat exceeds that which can be disspiated, it'll cook. I yank the motor-end fans and mount fixed speed fans on all mine... even the machines I expect to run at a reasonable speed, because when you overspeed them (beyond 60hz) they become air-raid sirens right quick.

Click to expand...

Thanks for the insight, it was just the kind of stuff I was looking for. Me being a simple ME sometimes I get confused when talking about things like “switching into an inductive load, and the end result is noise that exists in the high frequency/high voltage realm,” but I do know enuff of the EE stuff to be dangerous!

So maybe working in my favor is I plan on running this 440/220 VAC motor at 220 VAC 3 PH. So hopefully that works in my favor with an oldtique motor with regards to its vintage insulation.

I will be breaking these units down for basic cleaning and testing. I’m assuming when conducting motor insulation testing we are talking about using a megger verses something destructive like hipot testing? I should be able to borrow a megger from work to test out the motor and generators before going too far with this project.

BTW, in this case, low speed operation motor cooling won’t be an issue as the VFD simply plans to run the motor that drives the main and exciter generators at full speed (60 Hz).

thanks
Brian

thermite said:

How 'bout I hold yer beer?

Click to expand...

Keep your hands off my beer! It keeps the "creative" thinking working!

DaveKamp said:

And it's quiet. I don't mind hearing a cutting tool digging into innocent metal, but I like listening to music whilst I work. As much as I like loud music, regardless if it's a symphony or a Ted Nugent concert, I prefer it by choice, not necessity... and with this setup, I got it.

Click to expand...

I do like banging my head to some good ted the sledge nugent like strangle hold!

Although your conversion sounds exhausting, I do appreciate the concept of boiling this down to a single motor and VFD to run the lathe otherwise there is a lot of other stuff in there making unwanted noise.

rakort said:

... otherwise there is a lot of other stuff in there making unwanted noise.

Click to expand...

Yazz. Fans and AC hum are rather noisy, ain't they?

No fans needed. Eurotherm/Parker-SSD 514C + ripple-filter for the armnature, SSD 507 + ripple filter for the field, OEM 3 or 5 HP Dee Cee motor and gearbox, new rubber mounts and pliable new "A" section Vee belts?

In direct-drive, threading or surfacing dis-engaged? Not yet in the cut?

The loudest sound is those pesky balls rolling about in the spindle bearings.

Vintage Carlye Simon and "Nobidy does it better.." .... or even "You're so vain.." seems to fit that sort of 10EE power, given that Simon & Garfunkel's "The Sound of SIlence" is a lie, acoustically...

rakort said:

.. being a simple ME sometimes I get confused when talking about things like “switching into an inductive load, and the end result is noise that exists in the high frequency/high voltage realm,” but I do know enuff of the EE stuff to be dangerous!

Click to expand...

Okay, here's a mechanical translation:

Take a horizontal beam, free at one end, fixed at the other. Let's say it has a section modulus capacity of 600lbs. Put an elastically supported load off the free end that's 480lbs... and since it's a weight on spring, you have Simple Harmonic Motion. In electrical sense, the equivalent is capacitance (the elastic) and inductance (the inertia) for a 'tank circuit'.

Now, while that weight is bouncing up and down, take a hammer, and whack the beam a dozen times.

The SHM of the 480lb weight is equivalent to AC waveform of voltage and current.
The shock and harmonics of the ringing beam, from the strike of the hammer, is the equivalent of switching noise.

Sum and difference of waveforms of the bouncing weight, plus the shock of the hammer whack, PLUS the harmonic action of the ringing beam, will present a stress in excess of the beam's section modulus, and you'll soon see a failure...

You could drive the AC motor at constant speed... but doing it with a VFD... I wouldn't... if you had a VFD in hand, and you were in MY shop, you'd get a motor, belts, etc., and make up a complete working drive system, and do a full swap... it's not that involved. PM me an email address and I'll send you pictures of what I did, or if you're around Davenport, just stop by and give mine a test-drive.

I recommend that if you wanna keep the M/G, either fix up your rotary converter, or use Peter's conversion method to make the MG motor run on single phase. There's a bit more electrical challenge to doing that ('cause you'll hafta pick your way through old, dark wiring), but it works fine...

rakort said:

I've been considering doing the same thing and running the lathe's native 3 ph motor with a VFD....brain dead simple mod and can leave all the oem stuff there if wanted and easily include the safety feature with the f/r drum switch that prevents the vfd/motor from firing up unless the switch is the off position. Other than that safety there is no interaction with the controls for the lathe.

Comments are right that clearly the original motor is not inverter duty rated as would be appropriate for a vfd. It is kind a roll of the dice. I understand the largest thing that makes a motor inverter rated is the "level" of the insulation. VFD/Inverters can introduce voltage peaks / spikes that can cause questionable insulation to fail.

I'm gonna chant with an EE about this, but I'm thinking in "gentle" variable speed service the voltage spikes may be minimal compared to hard accelerations and decelerations and frequent speed changes that a rated motor would be exposed to.


Now to further tempt the issue one can acquired a 5 hp VFD for slightly north of $100.

4KW 22V 5HP VFD SINGLE PHASE VARIABLE SPEED DRIVE INVERTER VARIABLE FREQUENCY | eBay

I know the drive is cheap Chinese questionable quality stuff.....but if you get 5 years out of it.....they will be $50 by then.

I'm about crazy enough to try this as I hear no one has done it yet.

Click to expand...

I am considering the same modification.. first off I will need to figure out how to re wire my 10ee to 230v from 460v

Bathgate1982 said:

... first off I will need to figure out how to re wire my 10ee to 230v from 460v

Click to expand...

We need more information on what it is that you're working with. Motor/generator (MG), tube drive or something else?

Here's a link that explains how to rewire a dual voltage, 3-phase MG 10EE to 220/240:

Not all MGs are dual voltage and not all are 3-phase. If you have a single voltage or 2-phase (not to be confused with single-phase) MG then it can't be rewired short of having the AC section of the MG rewound at a motor shop.