10EE solid state conversion

I have followed the trail of other members difficulties with their tube-type 10EE drives on this web site. Since I had the good fortune to find a fellow who solved my most vexing Monarch problems, I thought others in this web group would like to read the following:

I have owned two 10EE’s for about 20 years. They came from the old Hamilton watch factory in Lancaster, PA. The older one is powered by an MG set and has worked faithfully (with a few repairs from time to time) ever since but the later one, a 1957 tube type has never worked since I bought it.

At a Lotus car club party held at my house last year, it was my good fortune to meet an electrical engineer, Don Butler who used to do field work for Reliance Electric. After examining my car for a while we began to talk about my two old Monarchs and the problems I had with the tube-type drive system. It turned out that at Reliance and at another similar job for another company, Don designed and installed control systems for large DC motors in industrial situations. In further conversation he said he would enjoy helping me with the challenge of producing a drive system that would reproduce the same characteristics as the original Monarch tube-type 10EE drive.

After some head scratching and examination of available drive hardware on the market Don decided to keep the old tandem wind rheostat, the field supply relay, the braking resistors, one terminal block and one of the two vertical plates at the right end of the roll out drawer (to hang all the components on). The later motor was hooked up to the output from the older MG drive set for a quick test and appeared to be in good condition.

Don did some research on the internet and found a really small manufacturer of bare bones digital motor drive hardware and softwear very close to where we live. Then all we had to do was to design a circuit, supply the necessary new (and old) switches, relays, fuses, terminal blocks and lots of expertise and build the thing. I say that loosely. He did all the figuring, soldering, calculations and constructing. All I did was watch and fetch wrenches.

The results were seen last week when we fired it up. After two sessions debugging the system I am pleased to report that the results are nothing short of spectacular. The motor is controlled with nothing more than the original controls. It operates on 240v single phase power. It starts off at 30 rpm and accelerates smoothly and quietly up to the nameplate 4,000 rpm. I don’t know the test for maximum power but I turned off a few red hot coils of tool steel big enough to take off your head if you got too close. Seemed torquey enough to me.

I’ll be enjoying my newfound work horse and looking for any problems in the future that might crop up.. Are there any others that might like to find out more hows and whys of this conversion? If so, contact me or Don Butler directly. His email is [email protected].

Regards Bill Bonta email [email protected]

Ps: Can anyone out there tell me what’s involved to stop the oil leaking into the bottom of the start relay box behind the headstock? My old MG type 10EE was a total loss system as far as I can tell but is it unreasonable to expect that the newer one should be dry on the outside? The machine seems to otherwise to have very little use and is in excellent overall condition.


[This message has been edited by [email protected] (edited 04-29-2003).]

Bill!
I think it would be very much apprechiated if you posted the diagram and details of your motor control here in this group. Myself I have an MG setup, but would be grateful to loose the humming noise as I have a shop in the basement of my house.

As to the oil leaks: The 10ee is designed to loose some oil, but there is as far as I have seen nowhere the oil needs to run down the outside of the machine. It is all designed to end up in the sump under the ways. There are drain holes in all compartments, you just have to look for them and probe around. As far as I remember the oil in the start relay box drains down under the main gearbox. The area under the gearbox has a channel leading through the way pillar casting down to the sump. This hole is often clogged with goo and old paint. Try to remove the start relay, and probe around in the old debris and gunk you are likely to find there.

Ole

It would be great to see a schematic, parts list and photos. Sounds Great!
Steve

Hello,

Here is more information about the new electronics in Bill's lathe.

The conversion is a straight forward replacement of the vacuum tube drives. A 3 Hp digital drive for the armature and an analog drive for the field. The field's analog drive stability circuit is re-tuned for the field coil reactance. New relays are installed to maintain the original function of the Start, Stop, Forward, and Reverse controls. The only deviation from the tube set-up is that maximum voltage to the armature is limited to 200 VDC. The tube drive was able to supply 230 VDC which is the nameplate rating of the motor. Therefore the conversion is limited, at this time, to ~87% Torque at nameplate Speed. At ~87% Speed and below it delivers 100% Torque. I will consult the armature drive manufacturer about a higher input voltage (the tube drive uses a 230 Vac to 270 Vac transformer) to make 100% Torque AND 100% Speed available. The other option for 100% Speed and 100% Torque is to use a new DC motor. The new motors have a 180 VDC armature nameplate rating instead of 230 VDC and will produce nameplate Speed and Torque with the new drives. A lathe with a nonfunctioning drive and a motor that needs extensive repairs is an ideal candidate for conversion! If the old motor has a gearbox a "C" face motor frame would be needed to mount the gearbox after modifying the gearbox mounting from
the old motor.

The only critical part retained from the tube drive is the speed potentiometer. It seems to be a custom made part and we are not sure if it is available new. So, I'm working on a functional replacement for the custom potentiometer using commonly available parts.

This conversion can be extended to any brand or size machine merely by selecting different voltage and ampere rated drives.

We would like to offer the conversion as a kit and are currently working on better packaging for easy installation. The kit will be supplied with flexible conduit with all of the wires installed and terminated inside the electronics box. The procedure will be removing all of the old wires and conduit and connecting the new the connecting the wires to the "M" contactor; the speed potentiometer; the start, stop, forward, reverse switches; and the motor. The final cost for the kit should be between $1000 and $1200 including shipping.

Thank you for your interest.

Don Butler

A solution which bypasses the "M" contactor would be an improvement. Perhaps even a requirement.

This contactor appears to be a "specific purpose" device, made by Cutler-Hammer for Monarch, just as are all the electricals in the relay box.

This contactor is a source of considerable trouble and appears not to be repairable.

In any case, the coil is single-voltage, so a 440/460/480 volt machine could not use the existing "M" contactor, anyway, if the drive was designed for 240 volts. A separately-derived source of 480 volts for that contactor would have to be provided in such a case.

I have reviewed the primary wiring of the 10EE at great length, and my conclusion is it is simply too much trouble to change the machine to 240 volts, as the primary side would have to be a "hybrid" of 240 volts (anode transformers, etcetera) and 480 volts ("M" contactor, work light transformer, filament transformers, etcetera), with about 350 VA being 480 volts (500 VA of 480 volts if the coolant pump is included) and the remainder being 240 volts.

Peter.

Hello,
This conversion is not a difficult one if you have a large trash can! The only parts that you need to keep are the FWD/REV switches and the potentiometers. Even those can be replaced with a little ingenuity.
We used the existing contactor in Bill's lathe because it is 230 Vac and it works. If either or both of those conditions had not been met we would have replaced it with a new relay. A 30 Amp rated relay with a 120 Vac coil is all that is required since the electronic drives do not "pull" current at power-up. This would have increased the cost of the conversion by about $50. The work light can be wired directly since we are using household 230 Vac with the neutral thus providing 120 Vac for every thing except the armature drive.
The coolant pump also must go since it is a three phase device and three phase is not commonly available in residential areas. We haven't bothered with the pump yet but it is not built "into" the machine therefore replaceable. I'm sure that 120 or 230 Vac single phase coolant pumps are widely available. Even hardware stores sell pumps for various applications that would be suitable (ornamental pond / fountain pumps for a water based coolant?).

Enjoy,
Don

For the pump, why not do your own "static phase converter"? Seems ideal for the purpose, and easy.

The potentiometer problem can be solved by some added electronics. All it has to do is imitate the "half turn" action of the two sections by controlling armature voltage for half, then field for the rest of rotation.

Only a single section pot would be required, with a "one-piece" controller.

Hello,
My impression of the cost of a new or used pump is that it is cheaper and, most importantly, much more robust than any electronic or electrical three phase converter for the existing pump.
As for the speed potentiometers they need to be electrically isolated from each other because the two drives used are not "isolated" drives. The SCR / Diode bridge is not electrically isolated from the regulator electronics. The cost to use two separate pots and regulators to simulate the special pots is much less than buying isolated drives or a "one-piece" drive.
If you haven't guessed yet my guiding principle for this conversion is correct function with the least number of parts and a low price. The only modified part I used is the drive for the field supply. Its designed function is to power a motor armature. I made a couple of easy modifications (after testing it!) to allow it to be stable supplying a motor field. This saved nearly $600. If the price difference had been less I would have chosen the standard part. I feel that custom parts and "trick" circuits are a source of future problems and can distract the owner from the function of the complete machine which is cutting metal.

Don

"Only a single section pot would be required, with a 'one-piece' controller."

I've done a lot of research on "packaged" and "open frame" phase-controlled drives which might be suitable candidates for a replacement for the 10EE's drive (Ward-Leonard and later), and no production drive provides for "field crossover"/"field weakening", although one claims a 200:1 speed range with a modification, although how this 200:1 range is obtained is not described.

And, none of these drives can provide the required function from 240 volts single-phase, although one or two claim to provide this function from 480 volts single-phase.

My conclusion is this ...

In order to obtain full function and performance from a replacement 10EE drive, that drive must:

1) be able to achieve 230 volts dc on the armature with maximum rated field voltage (and current), and

2) be able to achieve minimum rated field current (and voltage) with 230 volts dc on the armature.

With the present commercial offerings, this mandates two independent drives, and two separate, but ganged, control potentiometers, as these independent drives have no common electrical nodes in common for the control potentiometers.

Peter.

Peterh: I just measured the time for one revolution at 3 1/2 seconds at minimum speed. That figures out to 17 rpm. EArlier I measured the maximum speed at 4000 rpm. Actualy Don could have tuned the motor for far higher speed but we both agreed that the manufacturers maximum speed should not be exceeded. Even at that, Don expressed admiration that Reliance had produced a motor and drive system with as wide a speed range as the Monarch has. Anyway, the calculation demonstrates that the speed range is 235 to one. The control system that Don built for me is unique in that it was designed for the Monarch lathe alone and not to be some "on-size-fits-all" commercial solution to any ones motor problem. I specified that the controls be the original controls in the original locations so that a person operating his Monarch for many years (such as I have been) could not tell the difference. He succeeded admirably in that regard. At present, the sustem produces full power and torque up to about 1000 rpm (Don would have to give the exact figure) and about 90% after that. At the maximum speed of 4000 rpm I'm not too concerned about losing 10% of the horsepower. My use of those high speeds is mainly for polishing operations and Don claims that this problem too can soon be solved.

Donald and Peter:

I thought from Donald's post that he had made a single controller handling both sections one way or another.

If not, then the exact same conversion techniques applied separately to two sections of an ordinary dual linear pot will work fine to emulate the action of the stock dual. You will want to be able to handle that, as many machines may have had that part robbed out, or it is defunct.

There are any number of ways of coupling across large voltage differences, depending on frequency range coupled. I routinely deal with this at work, as we do high power PWM audio amplifiers operating at 300 to 500 kHz and up to 2 HP of audio output.

Some thoughts, assuming NO part of the original setup can be salvaged, including pots etc:

A pwm signal from a single central controller would be easily optically coupled to slave PWM power sections for armature and field.

A DC level and a simple microcontroller could be optically coupled to a serial input DAC for control signal transmission to conventional commercial SCR controllers.

More simply, a low level PWM from the control head could be optically coupled to the commercial controller's input.

Or, a simple on-off signal thru the opto could couple the control signal to the SCR drive for a custom SCR based controller. The phase delay could be based on a low-level AC signal from a sensing transformer, with only the SCRs and the "hot" end of a feedback coupler at the high line voltage.


Overly complex? Maybe, maybe not. Sometimes re-creating the "feel" is important, more so than a few bucks or the exact technology used.

"the calculation demonstrates that the speed range is 235 to one"

Good to know, as commercial drives claim about 20:1, while a few claim 200:1 "with modification".

But, those drives don't employ "field crossover"/"field weakening", while the Monarch's drive, and many hoist- and elevator-type drives do.

If field-crossover is not used, then a purported 200:1 ratio would all be on the low side of the controlled motor's base speed, whereas the Monarch drive's 200:1 ratio would include both the low side of the motor's base speed plus speeds above the motor's base speed.

It is relatively easy to construct a drive which has a high ratio, but doesn't go above the motor's base speed.

Going above the motor's base speed, with complete safety, is a challenge, and many of the components in the Monarch's drive are dedicated to that end: the separate shunt field power supply and its control (in tandem with the armature power supply's control), the Field Failure Relay, and interlocks too numerous to enumerate here.

Hello Again,
There seems to be several issues raised that I'll try to address. First, speed range. The drive is capable of starting at zero speed but that is not safe for the armature. If the armature is stalled (stationary) and current is flowing the commutator bars under the brushes can over heat and "wedge" themselves proud of adjacent bars. That will require the removal of the armature and the machining or replacement of the commutator. Therefore I set a minimum armature voltage that will guarantee rotation. I could set it lower than it currently is but to go much lower I would prefer that have tachometer feed back to prevent a stall condition.
Field weakening requires a separate power module and regulator. No manufacturer provides field weakening from the same power module as the armature although some manufacturers put the two systems into the same package (i.e.: Reliance Electric) so it seems to be "one piece." There are two ways of connecting the armature and field regulator together. The easy way is the way Monarch used, two special wound pots ganged on the same shaft. Cheap and no stability problems under load. The hard way is to have the field controller "look" at the armature voltage. When the armature voltage approaches maximum, say about 210 VDC for a 230 VDC nameplate, the field starts to weaken. When the armature voltage reaches its maximum the field regulator is set to provide minimum field current, therefore maximum speed. This set-up requires tachometer feedback and can have stability problems under varying load. This also costs more money but is easier in a multiple motor system.
As for replacing the special wound pots. All that is required is a simple circuit comprised of two pots ganged on the same shaft and a DC power supply double the voltage needed for the speed reference to the drive regulators and a Zener diode (with the proper current limiting resistor in series) to "clip" the output voltage from the pots. Say the regulator needs 10 V to produce maximum speed. You put 20 V across the pot and connect a 10 V Zener diode to the wiper (output) of the pot. This will produce a 10 V output for half of the pots rotation and 10 to 0 V output for the other half or its rotation just like the special wound pot. The digital drive I used for the armature has a 24 VDC output available. The analog drive for the field will need an additional power supply for the pot but a lower power single voltage supply is simple and cheap.
Finally, there are many answers to a complex question. I try not to become attached to any one answer but let an answers simplicity and suitability select itself. I have in the past applied/designed, commissioned and repaired many drive systems. Mostly multiple motor systems (as many as 30 to power one machine) with motors up to 1000 Hp. Regulators that ranged from Ward Leonard to microprocessor. I don't say its to impress you but to impress upon you that a lot of thought and experience went into this conversion.

Which ever way you choose to re-power your machine get it running and have fun.

Don

"The drive is capable of starting at zero speed but that is not safe for the armature."

Most definitely.

That's why Monarch's drive has a minimum speed pot, and that pot has a shaft lock on it.


"No manufacturer provides field weakening from the same power module as the armature although some manufacturers put the two systems into the same package (i.e.: Reliance Electric) so it seems to be 'one piece'."

Quite true.

I haven't yet found a factory-made drive of 5 HP and under which supports "field crossover", however there are many in the over 5 HP (to many hundreds of HP) which do.

Those drives start at a thousand bucks, and up, just for a 5 HP version.


"Which ever way you choose to re-power your machine get it running and have fun."

The ultimate truth.

My experience with lathes and motors only began last December
so please bare with me.

While using level (non-chopped) DC as a source, have not experienced
the near zero speed problems discussed.

Used the lathe at near zero speed to wind an inductor.
A pic of the finished inductive reactor is at:
http://www.paladino.info/~jim/10EE/reactor.html

Set at near zero speed a go/no-go foot switch and contactor were used for
armature control, as (for me) bifilar winding requires the use of both hands.

The motor was quite, very smooth and drew only a small armature
current.

Why could cause the difference at near zero speed??

If you try to do with a speed control what you ought to do with back gear, i.e. take deep high torque cuts, the current goes way up. This, combined with lack of fan cooling at low speeds, overheats the motor.

Power is related to torque and speed (rpm) as in the force times distance deal. At low rpm, torque must be large for same power, so the current, which produces torque, increases.

Winding wire should be pretty much a cake-walk by comparison.

A comment on using a 200vDC drive for the armature. Several years ago a friend started a conversion project on a 10EE that was missing all of its control equipment. We did some experiments with a 3hp motor to check its operation. We had a problem with field weakening when the armature voltage was less than 230v - specifically, if the armature was operating at less than 230v, when the field was weakened the armature current increased to the point of overload. Unfortunately, I do not remember how much lower the armature voltage could be, but it was enough that he bought the more expensive controller from KB Electronics that is rated for 230vDC output with 230/240vAC input.

Just thought of another detail: the motor was running unloaded except for the drag in the gearbox.

"... but it was enough that he bought the more expensive controller from KB Electronics that is rated for 230vDC output with 230/240vAC input."

Which KB cntroller was that?


Clearly, the Reliance and GE motors are designed for the armature voltage being increased as a function of the speed control pot from the programmed minimum RPM, which is actually the minimum aramture voltage, up to the maximum armature voltage, after which, and only after which, the shunt field (which had been held at 115 volts before) is allowed to be reduced as a function of the speed control pot to the programmed maximum RPM, which is actually the minimum shunt field voltage (while the armature voltage is held at 230 volts).

I'm wondering if anyone else here has noted that the Monarch drive supplies 245V to the armature at max, and not 230V? I was a little surprised, but apparently they drive the motor a little bit harder than the nameplate spec.

Also, the minimum voltage is adjusted to 98V in the setup (real old spec seems to have been 75V), and that's later bumped up to 102V by the compensation adjustment). So I'd suggest that 100V is likely in the ballpark for the minimum armature voltage.