[Fastest1]

I am thinking of removing my dc servo motor and replacing it with an AC motor. I would like to run a 1 hp 120vac tefc style motor if possible. My questions are
Is there a problem with 120v for this small hp motor?

Can I control the speed thru Mach of a single phase 120v motor and how? PWM? VFD?

I see alot of suggestions of a 220v 3 phase motor and a vfd/inverter or something. But if 1-1.5 hp is all you need is that necessary? I believe that I could run an optical sensor on a pulley for a tach in my G540 then threading would be fine. I dont have 220 in my garage yet and nothing else on the machine needs 220 now, even though the DC servo motor is a 148vdc motor. It uses a step up transformer. I dont mind using the existing motor but it means reconfiguring the old power supply and controller and interface it with the G540. Might be much easier to go AC.

[Al_The_Man]

Both methods generally use ±10vdc to control speed, so it will need a PWM to analogue converter for either.
For a 120vac motor it is going to be 1 phase and they do not take kindly to variable speed, so if going AC you would need a 3 phase motor, which would mean a VFD with 240v 1phase input.
Al.

[kevin swan]

look up KB electronic controles model KBVF-24D it is 120 volt in put 3 phase output i have one on my hone they probley make nicer vfds now as this one is apx 8 yrs old

[Fastest1]

Kevin are you running a 220 3ph motor on 120v with that controller? Do you get the marked rpm of the motor? BTW they still make the 24D & F. Also a 26D & F. Are you controlling the rpm thru Mach also?

[kevin swan]

Fastest1 I am running a 1/2 hp 220v 3ph moter with this. it has no tach so I cant veryfy the rpm. I think I run it at apx 800 rpm max.The control came built in the hone as oem .The speed is controled with a pot. as the hone is non cnc good Luck hope some of this helps. kevin

[mactec54]

Fastest1

You need to do more searching, try the drive ware house, for a Hitach drive you will get one to do your job from them, they have 120v input 220v 3ph out & you can run most drives with Mach This is one of many drives that will do the job

You need to have a 3phase 220v motor as well not single phase

[Fastest1]

Thanks to all regarding the responses and opinions. I will check into the drives. I am still curious why a single phase is any different than 3 phase regarding speed control. On the typical drives we are referring to (that use 120vac in and produce 220vac 3 ph out). If I use a model for the 1.5-2hp, is it alright to use a 1 hp with it and just have the extra capacity if I want a larger motor in the future? I am also trying to retain the motors original location and size may be an issue. A 56C might fit but it is going to be close. I am going to look into other frame sizes.

[Al_The_Man]

A single phase induction motor is actually a split phase motor that most use a capacitor to split the phase, dropping the frequency tends to make it drop out of run when going to low rpm's.
You can oversize the VFD, the motor details you are using is loaded into the parameters to take care of this.
The 1 phase motors you may see with speed control are usually Universal motors, which are quite a different motor.
Al.

[Fastest1]

Al thanks for the constant source of answers! Most of it is over my head but you help the layman so well. Good to know that oversizing isnt an issue. Now time to look at motors though I am still considering resurrecting the DC Servo motor and its controls.

[Al_The_Man]

What is the issue with the present DC servo/spindle?
Al.

[Fastest1]

Al, the old machine is a Dyna DM 3000. The controller was missing from day 1 (the machine is used) and all connectors had been removed from their places on the boards. After a good cleaning and no parts to install, I started plugging in all the connectors. The wires were all marked very well as were the boards. Everything went right into place. Hit the power button and it all came to life. Of course I had no way to control it and I wasnt going back to Dyna's 1980's electronics. But the spindle did work and I had rpm control thru the pot. I pulled all of the existing electronics out including the spindle driver board. The machine has a transformer in the back that steps up the 110vac to 148vac and then rectifies it to DC and has a relay that I am guessing turned the spindle on and off. I would need to resurrect the power supply (which I would like to do if only for the knowledge) and retain the DC motor til it proves to be too weak. It might not prove too weak for me. On the driver board besides the typical inputs and outputs for the motor control, there seems to be a few other plugs that connect to the board. I dont know if they are all needed or not. Also there is some form of amplifier on the circuit. The manufacturer is still in business for their bigger machines but these educational models were discontinued quite a few years ago. They are helpful to an extent but arent really into the technical end of the older controls. I could attach a picture or 2 if that would help. The motor itself is a SEM MT30. I guess the thing that intimidates me the most on the DC motors is all of the wires going into the housing, they are well labeled but dont make sense to me. The wires seem to be marked just like each axis. Anyway I would love to use what I have til I need or learn more. Give me hope Al!

[Al_The_Man]

I put a SEM servo motor on a lathe for a friend, I used a KB 4 quadrant SCR drive off ebay, and ran it off the 240vac.
Using the tach option together with the servo tach gives good rpm control and the 4 quadrant gives braking and bi-directional control with one pot, or ±10vdc from a controller if you need it.
The 2 quadrant, you have to use a reversing contactor and uni-directional pot control.
Al.

[Fastest1]

Al, say I choose the SCR as you used on the SEM. If I move over to a 240vac supply for my machine does the KB have a maximum adjustable voltage? The reason I ask is that everything I read refers to the motor as a 140v max. All of the drives I see claim either 90/180v or something besides 140 exactly. What puzzles me also is the fact that it is a 120vac input and the motor is 140vdc. There is a large transformer and I am trying to figure out how to measure its output.

[Fastest1]

Al, do any of these parts clear up anything.

[Al_The_Man]

The 240v input model is for a 180v motor, using the SEM 140vdc motor you can set the max range on the SCR drive in order not to over speed.
With the SCR drive it is AC input, so a DC power supply will not work, you need to use direct off of 1 phase 240vac outlet or a transformer with 220~240v secondary.
Al.

[Al_The_Man]

I don't recognize the controller, the transformer is hard to see what the ratings are, pic 5 & 6 are an ac mains noise filter.
Al.

[Fastest1]

Al, thanks again for the speedy response. I did understand the drive you were referring to required a 240vac input not to reuse my power supply. I did want to reuse both my original power supply (transformer in pic) for the SEM and interface the old driver board with my G540's vfd/pwm output if that is possible. It looked like on the spindle driver board there was a place for the 0-10v signal but I could be misunderstanding what I am seeing. BTW pics 2 & 3 are the same board.

[Al_The_Man]

Do you have the manual on the drive? If not try a contact at Dyna Mechtronics, they may send you one?
Al.

[Fastest1]

I have one for a 3000H and mine is just the 3000 but they might be the same. This was provided by a fellow member. does it help?

[Fastest1]

Al, I am sorry. I did find a schematic for the 3000's spindle driver, soon I will figure out how to get it here!