Monarch 10EE with Baldor 20H Line Regenerative Digital DC SCR Control

Hi,

I bought a lathe about 2 years ago and only recently started to set it up. I have a American Rotary AD20 which apparently puts out 3 phase delta, and the baldor is designed to be set up with 3 phase wye.

Here is the manual:

http://www.gain-control.com/Manuals/20H.pdf

where it gives this warning:
Baldor recommends not using “Grounded Leg Delta” transformer
power leads that may create ground loops and degrade system
performance. Instead, we recommend using a four wire Wye.

So, from what I understand, functionally, the difference is that the manufactured pole is 240 to ground vs 120 to ground. The American Rotary manual recommends a delta-wye transformer, which I'm assuming is the 3 phase transformer on their website that would be ~$1800.

Products

If everything I've assumed is correct, it probably isn't worth it to convert the supply to wye, so if operating the control off of delta will damage it, odds are the most cost effective way to get it to work would be to convert the lathe to work off of delta? I'm not that familiar, but I believe the previous owner or previous previous owner converted the vacuum tube control to this baldor control.

So, I guess my question is what my options are, and whether I can operate the lathe at lower power for minor projects until this is resolved. I'm not particularly looking forward to dropping a ton of money or to dive into what changes were made to the wiring and what would need to be done.

Thanks!

Danny

The only difference between the delta output of a phase perfect or a rotary converter, is that the invisible neutral isnt ground, but rather 69vac away from ground.

So if you actually need 208/120wye. Then From 240v delta you need a transformer. There is a way to do this with three, 120:16 vac transformers* btw, but the neutral will not be ground. If you need the neutral to be ground then you need an isolation transformer.

*kva rating about 15% of rated load.

Based on the description from the previous seller and that it's "240" and that it has a 5HP motor/DC drive, I think I have the BC20H205–CL, which has a listed 230VAC input.

I measured the no-load output of my RPC, and got:
T1-T2: 249.4
T1-T3: 252.4
T2-T3: 251.5

Does this help me or hurt me?

Far as I can tell reading the manual http://www.gain-control.com/Manuals/20H.pdf , the only real concern is that one of your phases gets a transient that causes current to flow through the MOVs. (page 13) since your generated line is at most 208v to ground this is less than the (most likely) 275 or 330vac rated movs in the unit. also notice it says recommended, not required for the neutral to actually be ground.

If you look at the schematic on page 82, you'll find the ground doesn't connect to anything.

an ungrounded supply is a problem, such as running it on an ungrounded open or closed delta isolation transformer, but it would still work until something other than that dc drive causes current to flow asymmetrically through the motor to "ground". a fault in the motor for instance would cause current to flow through the drive into the dc motor causing the ac 3 phase ungrounded system to have voltage on it (relative to ground) when it shouldn't.

since dc motors have substantial inductance you could have energy stored in an intermittent fault and when the fault clears you get a lot of voltage causing current to flow through the MOVs in the drive. this could happen for a long time until the movs fail and then the drive fails later.. and sure enough it was "because" the supply was ungrounded, when in this example, that wasn't the direct cause, and if the supply was grounded the fault in the motor would hopefully have caused the drive to fault.


again, you won't have this problem and you can wire L1,2,3 right into your rotary phase converter.

krap101 said:

Based on the description from the previous seller and that it's "240" and that it has a 5HP motor/DC drive, I think I have the BC20H205–CL, which has a listed 230VAC input. View attachment 223484

I measured the no-load output of my RPC, and got:
T1-T2: 249.4
T1-T3: 252.4
T2-T3: 251.5

Does this help me or hurt me?

Click to expand...

Per the manual, Section 5, MN720 Specifications and Product Data, page 5-1:

The inout voltage range for 230 VAC Models == 180-264 VAC 3-P @ 60 Hz.

You should be OK.

Used-but-good Delta => Wye transformers can be had for mebbe $600 up to 30 KVA. You NEED only a 7.5 KVA per the manual. A larger capacity one may be easier to find used at a good price.

Baldor's reasoning for wanting Wye with a proper (rederived...) Neutral is explained, and is a sound one.

Suggest you heed it.

SCR-class DC Drives are noisy buggers, so a "drive Isolation" transformer is a Very Good Idea in any case.

Excellent, thank you for all your help!!!

Sort of final side note, I measured T3-Ground, and got 219.4 VAC (unloaded). The only reason I bring this up is because you mentioned T3 to ground being 208V max, and wanted to make sure I wasn't leaving out any important information. Odds are though that the voltage drops to the 208 or so under load.

The other thing is that the RPC is sized for much more than the 5HP motor on the lathe (4x) and that aside from starting, I'll probably be running much less than the 5HP. If I'm understanding things correctly, that should also reduce the magnitude of the transients I should see?

thermite said:

Per the manual, Section 5, MN720 Specifications and Product Data, page 5-1:

The inout voltage range for 230 VAC Models == 180-264 VAC 3-P @ 60 Hz.

You should be OK.

Used-but-good Delta => Wye transformers can be had for mebbe $600 up to 30 KVA. You NEED only a 7.5 KVA per the manual. A larger capacity one may be easier to find used at a good price.

Baldor's reasoning for wanting Wye with a proper (rederived...) Neutral is explained, and is a sound one.

Suggest you heed it.

SCR-class DC Drives are noisy buggers, so a "drive Isolation" transformer is a Very Good Idea in any case.

Click to expand...

So, I'm trying to set up a shop, and this lathe is the first "big" thing going in. I could see myself buying a delta-wye converter if most equipment tended to be wye rather than delta, but it seems to be the opposite. Otherwise, if having the converter would be a sort of future proofing, then I wouldn't be overly opposed to buying one. Other side though is that they appear to be quite large and heavy.

So, in terms of "cost" of running this on delta, are we talking about reduced life of the components or dangerous for me to operate? Does more electrical noise result in more vibration?

krap101 said:

So, I'm trying to set up a shop, and this lathe is the first "big" thing going in. I could see myself buying a delta-wye converter if most equipment tended to be wye rather than delta, but it seems to be the opposite. Otherwise, if having the converter would be a sort of future proofing, then I wouldn't be overly opposed to buying one. Other side though is that they appear to be quite large and heavy.

So, in terms of "cost" of running this on delta, are we talking about reduced life of the components or dangerous for me to operate? Does more electrical noise result in more vibration?

Click to expand...

I'm "wishing" to put a Delta-Wye output transformer on all three of: 2 X 10 HP Phase-Perfect, 1 X 10 HP RPC. Safer all around, and "handy" to have the 120 ++ VAC to run coolant pumps and task lighting..

As to the "nominal" voltages, such as 208 /120?

Utility mains service voltages have been creeping up for Donkey's Years.

My nominal was 220/110, then 230/115, then 240/120 VAC has been pretty consistent for many years now @ 245-246 ~ 123 VAC.

If I can find older nominal 220/230 Delta -> 208 Wye, even with no adjusting taps, the 208 / 120 Wye will be proportionately higher as well.

As long as you keep the line to ground transients below the breakdown voltage of the movs then there is no problem with an ac supply that isnt symetrical to ground.

Your drive should not have a problem with corner grounded 264vac delta. But that makes the transients much more likely to degrade the movs.


Its an ungrounded supply that lets weird stuff happen

johansen said:

As long as you keep the line to ground transients below the breakdown voltage of the movs then there is no problem with an ac supply that isnt symetrical to ground.

Click to expand...

Sorry. It isn't an armchair philosophical discussion point as to what could be might be, or even should be.

Baldor or their contract specialists designed and built the particular drive under discussion. They specified Wye. They explained why they specified Wye.

Some other drive may differ. This one does not.

they recommended it, not required. 275 or 330vac movs are the only thing that connect the ground to the supply, and they aren't even on the schematic.

So based on the feedback both of you have provided, I believe that running the motor controller off of delta wouldn't be unsafe and if something breaks it'll be the controller itself.

I don't have a coolant pump that would need 120vac so maybe everything will work out?

krap101 said:

So based on the feedback both of you have provided, I believe that running the motor controller off of delta wouldn't be unsafe and if something breaks it'll be the controller itself.

Click to expand...

So sayeth Baldor, yes. 3-Phase (only) DC Drives are seldom as cheap as single-phase ones, so. Your risk. Your "plan B". Your call.

I don't have a coolant pump that would need 120vac so maybe everything will work out?

Click to expand...

OEM pumps were 3-Phase. Single-phase pumps in either/both 120/240 are cheap enough I bought new rather than have to be bothered.

Delta/Wye transformers not a good idea on RPC's

thermite said:

I'm "wishing" to put a Delta-Wye output transformer on all three of: 2 X 10 HP Phase-Perfect, 1 X 10 HP RPC. Safer all around, and "handy" to have the 120 ++ VAC to run coolant pumps and task lighting..

As to the "nominal" voltages, such as 208 /120?

Utility mains service voltages have been creeping up for Donkey's Years.

My nominal was 220/110, then 230/115, then 240/120 VAC has been pretty consistent for many years now @ 245-246 ~ 123 VAC.

If I can find older nominal 220/230 Delta -> 208 Wye, even with no adjusting taps, the 208 / 120 Wye will be proportionately higher as well.

Click to expand...

Once you go to a Delta Wye transformer on a RPC, you always have the weak manufactured phase affecting all 3 phases, no solid power company 120/240 available now, just a false hope of something better.

I finally figured this out while working on a quarter million dollar 5 Axis CNC stone saw. It was running on a large RPC.
They started frying motors after the MFG service made them install the Delta/Wye transformer.
Seems that the VFD motor control units didn't know enough to turn off the transistors when the control circuits crashed, leaving the DC connected to a winding long enough (no PWM) to toast them then finally burning a spot open. Several motors later I had them install a 3 Phase generator until they got real 3 Phase.
That was over 2 years ago, not even a hiccup since.

Bill

hitandmiss said:

Once you go to a Delta Wye transformer on a RPC, you always have the weak manufactured phase affecting all 3 phases, no solid power company 120/240 available now, just a false hope of something better.l

Click to expand...

Surely hope to see SOME "leveling effect", but far, far, from a perfect one ELSE RPC + transformer would be a much more common go-to as a problem solver vs pricier Phase-Perfects.

Our design goals and philosophy differ, of course.

All-manual shop, only load off the RPC are 3-P final-drive & traverse/rapids motors.

All-else as needs utility-mains-grade single-phase, be that 240, 120, coolant pumps, task lighting, or control transformers gets exactly that, FROM the 1-P mains, not from the RPC. That would include control electronics PSU or DRO's. if I HAD any such, of course. So far, not.



Prolly will add DRO in due course. 10EE no real gain. The Cazeneuve, OTOH, threads in inch as well as Metric, but feed dials are metric only. A DRO could be "nice to have" on the Quartet combo-mill, too - partly because it IS a "combo" with a bit of extra flexibility / need of ready reference base, so...