Rewiring 13x30 monarch model 61 from 480V to 240V

milosav2 · Jan 1, 2023

I am looking at rewiring the motor on my Monarch model 61 13x30 lathe from 480V to 240V, and there is no motor tag on the motor or anywhere inside the motor access door. Luckily, the wires were labeled though (maybe by the last electrician that touched the motor ... as you can see in one of the pictures below, a blue service tag is attached to the motor).

You can see in one of my pictures below my notes on how the motor is connected to the lathe electronics enclosure. The connections appear to math the 'High Voltage' diagram here:

https://control.com/uploads/articles/image2_motors.jpg

To rewire the motor itself is the easy part for me; I can just rewire it per the 'Low Voltage' diagram linked above, right?

Now, to rewire the cabinet and the square D safety switch (a picture of both is linked below) is where I am stuck.

Inside the cabinet at the bottom there is a control transformer with a red tag, it is currently wired for 480V out as you can see by the jumper between the screws at the top. That's simple enough, I can just jumper it per the diagram on the red tag for 240V. My question is, what else do I need to do in this lower cabinet and also at the square D safety switch at the top?

I will of course be running the machine from 240V single phase at the wall via a VFD to 3 phase 240V.

A bunch of pictures here:

https://imgur.com/a/eQGJGK7

Cal Haines · Jan 2, 2023

I think that you've covered most of the basics, except that you probably need to change the overload heaters on the main AC contactor (often called a motor starter). There may be other things specific to a model 61 that I don't know about; hopefully someone who knows will jump in.

Mr_CNC_guy · Jan 2, 2023

You need to ensure that there is no switch or relay between your VFW and motor.

milosav2 · Jan 2, 2023

Cal Haines said:
I think that you've covered most of the basics, except that you probably need to change the overload heaters on the main AC contactor (often called a motor starter). There may be other things specific to a model 61 that I don't know about; hopefully someone who knows will jump in.

Can you point out the heaters in my pictures.

johnoder · Jan 2, 2023

milosav2 said:
Can you point out the heaters in my pictures.

Right next to the RESET items I'd guess. Heaters are always part of a circuit that includes the starter coil (s)

milosav2 · Jan 2, 2023

johnoder said:
Right next to the RESET items I'd guess. Heaters are always part of a circuit that includes the starter coil (s)

I see. So I need to get 240v heaters. Where would I get them? I would imagine they are hard to come by for these old machines?

beckerkumm · Jan 2, 2023

If you are planning to run off a VFD, most of the old electrics will need to be removed. The switches will need to be wired to the VFD and the unit will determine the proper type of switch. The old 220v switches aren't always the best choice so you end up swapping them. The two starters, forward and reverse will be removed as the VFD will now do that. Running from a VFD involves some mods. If you were running off a RPC or Phase Perfect, you would need to swap out the heaters to a higher amp and likely the coils, possibly both starters as they may be undersized. I'm starting a VFD conversion on my Monarch 60 as the wiring all needed to be redone. Mainly to get some speed variation.

You will also want a switch to power up the VFD and keep your safety switch, not to use as a switch, but to serve as fuses between the vfd and the motor. I've found it important to protect the VFD from the machine.

Mark Jacobs here is the VFD conversion guy ( among others ). If you go that route, do it correctly as the electrics are expensive and the machine is powerful.

What size motor and what rpm ? Dave

milosav2 · Jan 2, 2023

beckerkumm said:
If you are planning to run off a VFD, most of the old electrics will need to be removed. The switches will need to be wired to the VFD and the unit will determine the proper type of switch. The old 220v switches aren't always the best choice so you end up swapping them. The two starters, forward and reverse will be removed as the VFD will now do that. Running from a VFD involves some mods. If you were running off a RPC or Phase Perfect, you would need to swap out the heaters to a higher amp and likely the coils, possibly both starters as they may be undersized. I'm starting a VFD conversion on my Monarch 60 as the wiring all needed to be redone. Mainly to get some speed variation.

You will also want a switch to power up the VFD and keep your safety switch, not to use as a switch, but to serve as fuses between the vfd and the motor. I've found it important to protect the VFD from the machine.

Mark Jacobs here is the VFD conversion guy ( among others ). If you go that route, do it correctly as the electrics are expensive and the machine is powerful.

What size motor and what rpm ? Dave

So you're saying I won't need anything inside the original monarch electrical box here:

https://imgur.com/npSjxE6

because the vfd can handle all of it's functions?

And then also to keep the safety D switch as a fuse safety between the motor and vfd, but just add a switch between the 240V single phase wall power and the vfd, correct?

https://imgur.com/d62iCWu

beckerkumm · Jan 2, 2023

Basically correct. You will need to wire the start stop, forward and reverse switches into your controls and may want to add an external braking resistor. I have Mark Jacobs draw up a system for me. You might want to contact him and see if he will do one for you as it should be pretty much the same as what he will do for me. I don't know his schedule and I hadn't planned on installing mine for a few months but I can tell you the system is well worth what he charges, especially when you are new to the conversion.

If you plan on other three phase machines, a balanced rotary converter or phase perfect might be a good choice. $2-5K is the cost range no matter what choice you make. VFD might be the cheapest for one machine but not for several.

Dave

johnoder · Jan 2, 2023

milosav2 said:
I see. So I need to get 240v heaters. Where would I get them? I would imagine they are hard to come by for these old machines?

I'd start with Square D and any model number - since your photos suggest that is who made the starter. I'd also suggest that the heater voltage have to be the coil voltage. I'm guessing here

milosav2 · Jan 2, 2023

beckerkumm said:
Basically correct. You will need to wire the start stop, forward and reverse switches into your controls and may want to add an external braking resistor. I have Mark Jacobs draw up a system for me. You might want to contact him and see if he will do one for you as it should be pretty much the same as what he will do for me. I don't know his schedule and I hadn't planned on installing mine for a few months but I can tell you the system is well worth what he charges, especially when you are new to the conversion.

If you plan on other three phase machines, a balanced rotary converter or phase perfect might be a good choice. $2-5K is the cost range no matter what choice you make. VFD might be the cheapest for one machine but not for several.

Dave

How do I get in contact with Mark? Do you know his username on here?

Cal Haines · Jan 2, 2023

Did you come here wanting to do a VFD conversion, or just get your machine running? Replacing the heaters will only cost few dollars, a VFD conversion is going to run hundreds of dollars and take a fair amount of time.

If you just want to get the machine running, I can probably help you.

milosav2 · Jan 2, 2023

Cal Haines said:
Did you come here wanting to do a VFD conversion, or just get your machine running? Replacing the heaters will only cost few dollars, a VFD conversion is going to run hundreds of dollars and take a fair amount of time.

If you just want to get the machine running, I can probably help you.

I only have access to single phase 240V in my garage, so I think a VFD is the only way....?

Cal Haines · Jan 2, 2023

A rotary phase converter (RPC) is another option. If you think you might have other 3-phase machines down the line, it's something to consider. An RPC probably won't cost any more than a VFD.

There are also PhasePerfect digital phase converters (link), they produce great 3-phase power from single phase, but are pricey.

I don't know if anyone here recognizes that motor or if it looks original. The HP rating can probably be deduced from the heaters that are installed on the motor starter. Be aware that not all vintage motors do well from VFDs.

milosav2 · Jan 2, 2023

Cal Haines said:
A rotary phase converter (RPC) is another option. If you think you might have other 3-phase machines down the line, it's something to consider. An RPC probably won't cost any more than a VFD.

There are also PhasePerfect digital phase converters (link), they produce great 3-phase power from single phase, but are pricey.

I don't know if anyone here recognizes that motor or if it looks original. The HP rating can probably be deduced from the heaters that are installed on the motor starter. Be aware that not all vintage motors do well from VFDs.

I have not 100% picked out a VFD yet, but I plan on going with this one:

https://www.amazon.com/LAPOND-Variable-Frequency-Inverter-Control/dp/B09GYH5CFX/ref=sr_1_5?crid=W51P7REKTYW1&keywords=variable%2Bfrequency%2Bdrive%2B15hp&qid=1672685067&sprefix=Variable%2BFrequency%2BDrive%2B%2Caps%2C89&sr=8-5&th=1

The reason I am going with a 15hp one is because this is a chinese vfd, and this lathe originally came with a 7.5hp motor; so I figured it would be wise to use a cheap vfd with at least double the rating of the motor. Now, this motor does not have a spec plate anywhere, so I am not sure if it's original or not, but it is very clean. I am hoping it's just a rebuilt 7.5hp unit.

If you have a better quality 7.5hp vfd in mind from a reputable manufacturer near the same price feel free to let me know.

Cal Haines · Jan 2, 2023

I'm not a VFD guy, so I'll leave that to others. You might want to ask on the VFD forum:

Transformers, Phase Converters and VFD

Machine voltage issues, three phase via single phase power, and variable frequency drives discussion >> moderator JST

www.practicalmachinist.com

dalmatiangirl61 · Jan 2, 2023

milosav2 said:
If you have a better quality 7.5hp vfd in mind from a reputable manufacturer near the same price feel free to let me know.

How often do you find better quality from reputable mfrs at chinesium pricing?

Check pricing on a similar sized vfd at Automation Direct, or used/new rpc's, maybe just buy a panel and supply the idler. If you want cheap and reliable, an rpc is probably your best bet. If money is no object, get a Phase Perfect.

beckerkumm · Jan 2, 2023

Wait before buying anything until you are sure what you want to do. Not all VFDs are created equal for what you may need and best to wait until you have a complete plan. I have boxes of electrical parts that I thought would work but ended up not quite correct.

7.5 hp was the smallest Monarch used ( I think ) but you should verify. It looks smaller than the 10 hp on mine which is a 326 frame. Mark is MKSJ here and works mainly with Hitachi WJ200 and lately Yaskawa drives. If you decide that the vfd is a better choice than a Rotary converter, you might want to pick one like the WJ200 that you can get a remote keyboard for. You can hook up the vfd to the safety fuse, and bypass the electrics and go directly to the motor. Since the monarch is a clutch lathe you can test it with the keyboard mounted where the switches are currently and make sure you have a machine in working order before going the full conversion route.

I run a Phase Perfect and am a huge fan of them but will also run a vfd on machines that benefit from some speed control or braking. Again, don't start buying stuff until you know the direction you want to go and if VFD, let someone in the know select the parts.

Here is the conversion for my smaller 5 hp lathe.

Dave

Cal Haines · Jan 2, 2023

I had the impression that VFDs in the 5 to 10HP range that run from single-phase 240 are not cheap.

For example, this supplier doesn't carry Hitachi VFDs of that type (they have plenty 3-phase input versions). All they carry in the 7.5 to 10HP range, with single-phase inputs, are Invertek drives, starting at $1300:

7.5hp vfd | 7.5 horsepower variable frequency drive

7.5hp VFDs for Any Application Available. Authorized Distributor of Top Brands. Get Free Shipping on $100+ Orders!

www.wolfautomation.com

AutomationDirect doesn't show any suitable Hitachi VFDs either. All they seem to carry are DURApulse drives and they have nothing in stock:

https://www.automationdirect.com/adc/shopping/catalog/motor_controls/ac_variable_frequency_drives_(vfd)/general_purpose#start=0&Horsepower_Rating_ms=(%20%227-1/2hp%22%20%2210hp%22)&Number_of_Input_Phases_ms=%221%22

beckerkumm · Jan 2, 2023

Most drives will accept single phase input if sized upward. The hitachi WJ200 110 LF would handle7.5-10 hp on single phase input. There really isn't much need to run a full 10 hp cut so it should suffice. Dave

Rewiring 13x30 monarch model 61 from 480V to 240V

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