Choosing right VFD or wiring for rotary converter?

[afreeland]

I just finished running a 220v sub-panel over to where my mill is located and was looking for advice on wiring. When I purchased my Super 55 Wells Index the guy I got it from also provided an idle motor, magnetic contactor, general contactor, start capacitor, switch and timer. However, I am not quite sure exactly on the wiring...I thought a VFD might be an easier path and not sure if the rotary converter setup is right (I thought they need run capacitors as well?).

Here is the specs of the motor on my mill:




I am not really opposed to the rotary converter but the wiring feels like a spaghetti mess that I don't fully understand. The magnetic contactor is hooked up to a 120v cord where one legs goes to the coil and the other leg runs to a switch and one side of the capacitor through a wire nut...the other side of the capacitor was unplugged.

I assumed that 220v would come from my breaker into the 'L' side of the magnetic contactor (In the image below, the top right side closest to red chair). Currently there was a white and black wire snipped on the 'L' side but no ground...and what seemed strange to me was that there was a red cable that went from the 'L' side to the other smaller contactor that is in the middle of the panel. That smaller contactor is hooked up to a timer that the guy said he never really used, so...who knows lol.

On the 'T' side there is a red,white,black wire that has a black sleeve around it...I believe that may go to the idle motor and then the idle motor would be pushing back that 3rd phase on perhaps one of those 3 wires. Then I was thinking that the mill is also connected on those same leads, the other 3 wires that are zip tied together and therefor getting the 220v from the breaker as well as from the 3rd phase being generated?




Here is the idle motor



The magnetic contactor L side


The magnetic contactor T side



For VFD was looking at this, which seems like it would be sufficient for size?

Amazon.com

If anyone has any recommendations for either path I would greatly appreciate it. Been trying to restore a lot of pieces on the mill and would love to actually see it run. Going to be super bummed if it doesn't work and been burning time and resources.

 

[benmychree]

Building your own rotary converter is easy, I built mine by using a static phase converter to start the idler motor, simplifying things considerably, but, yes, you do need oil filled capacitors to balance the manufactured leg.

 

[markba633csi]

The function of the small contactor is to switch the capacitor in for starting the motor then switch it out after a few seconds.
You should go online and find a clear diagram to work from. You can't work with a rat's nest like that. Too dangerous.
Also, green wires should never be used for power, only ground.
-Mark

 

[Ulma Doctor]

the RPC could be wired up in a matter of a few moments, the VFD will take wiring it up, plus programming.

the top of the contactor has a black and a white wire stub sticking out- this appears to be the input power legs
the bottom of the contactor has Red, White and Black ( as well as White, Green and Black- disregard [or remove] these wires to minimize confusion)
these wires power the idler motor
you can connect the power wires from the mill to the errantly colored White, Green, and Black wires at the contactor or you can make these connections inside the motors electrical enclosure. ( i usually put a Nema twist lock plug for output on the idler motor)

your mill will unlikely be affected by not having a balancing capacitor- there is no real need for it for a milling machine motor- i have run hundreds of motors without balancing capacitance- don't believe the hype there


here is my design for an unbalanced unit- it worked for 20 years before i had 3 phase at my shop

Rpc simple design unbalanced

Rpc simple design Here's a simple plan for an unbalanced 220/240 v single to 3 phase converter. this design will start ANY 3 phase motor of ANY horsepower with a change of start capacitors! keep in mind,the contactor coil is 220v in this design, adjust coil voltage for high voltage use(480v)...

www.hobby-machinist.com

 

[Nutfarmer]

Your mill motor is two speed. If you switch different speeds with the VFD on there is a chance of frying the VFD. If using a rotary converter you can still use the two motor speeds. The only way I know of using a VFD on a two speed motor is to pick one or the other speed. I know of no way to use both speeds with a VFD. Maybe some of the electronic experts here could expound on this further.

 

[matthewsx]

I chose to go with a static converter from northamericaphaseconverters.com on my new/old horizontal mill.

I do have a 5hp idler motor and a 2hp single phase motor that can act as a pony but it's just simpler to use the static. I can always hook up the other motor and have a rotary converter but I don't think I'll miss the extra HP and when I hooked up the idler it just added to the noise....

Don't think I'll miss the power on a hobby machine....

John

 

[metric_taper]

I started out my home shop with a home built RPC. It worked well for the first few years, but I always disliked the noise, and that it was on the opposite end of the machine shop to start and stop. That was 30 years ago, and when I saw how inexpensive VFDs were, I switched over to them. The variable speed is a super asset. And you can program the drive to display RPM, assuming you leave your belts in the middle speed range, as you program in a scaling factor from HZ to RPM. My motors were all 4 pole, so I set the max Hz of the drive to 120, give a very good speed range of the spindles.
I even removed all the single phase motors from the lathe, drillpress, and bandsaw to install VFDs. It makes dialing the RPM for the SFM of the material and tooling you're using simple. I started with cheap Tyco drive (FM100), that was of the scalar type, that would not run the lathe down to low RPMs without cogging. I learned you want to get the vector drive type for good low RPM power. On the lathe, I can spin it slow enough with the torque needed to thread with taps and dies, and it does not stall out.
I've purchased used drives off Ebay, Craigs list, with great results. Just make sure they are for 200volt class input, as the 400volt class is not usable in the home shop (unless you use a voltage doubling transformer, as they will trip out on undervoltage).

 

[markba633csi]

I could help you put together a clear diagram if you can do a bit of legwork and post the data for the components you have- I would need to see the terminal connections for the contactors and the timer, then we could rewire it in a clean fashion and keep you from making fireworks or getting shocked.
The data sheets should be available online if you look around.
If I was facing a pile of parts like that this is how I would proceed- You don't want to guess when dealing with 240 volts
-Mark

 

[Ulma Doctor]

Your mill motor is two speed. If you switch different speeds with the VFD on there is a chance of frying the VFD. If using a rotary converter you can still use the two motor speeds. The only way I know of using a VFD on a two speed motor is to pick one or the other speed. I know of no way to use both speeds with a VFD. Maybe some of the electronic experts here could expound on this further.

the op can easily wire in a 3PDT switch to switch between the 2 speeds without damage to the VFD provided that the load was not switched during operation.

the motor works in both speeds

 

[afreeland]

I could help you put together a clear diagram if you can do a bit of legwork and post the data for the components you have- I would need to see the terminal connections for the contactors and the timer, then we could rewire it in a clean fashion and keep you from making fireworks or getting shocked.
The data sheets should be available online if you look around.
If I was facing a pile of parts like that this is how I would proceed- You don't want to guess when dealing with 240 volts
-Mark

That would be greatly appreciated!! Seen that using potential relay can be useful and easy to wire... Not opposed to picking one up if it simplifies anything.

Aromat fc50-ac120
- Magnetic contactor
- Datasheet: https://s3.amazonaws.com/Icarus/DOCUMENTS/Siemens_Datasheet_2411.pdf (page 8)

C25BNB230A
- General purpose contactor
- Datasheet: https://www.farnell.com/datasheets/1993429.pdf (page 5)

Baldor 5hp 230v - Idle Motor
- Datasheet: https://www.baldorvip.com/Product/InfoPacketExternal/?id=M3218T

at-3a s&h
- Timer 110v
- Not much info on this particular model

Basic turn knob that sits on one leg of the coil to turn whole setup on/off.


I started trying to make some basic diagram but I get lost at the capacitor piece. I think I get that the general purpose contactor is there to kick the capacitor off once the motor is going. In the diagram below, I think currently, instead of the wire nuts they are all simply joined on the `T` side of the magnetic contactor, which seems nice perhaps?



Here is the diagram that is directly on the timer itself


Here is the start capacitor
aero-m 710-850 MFD capacitor



Also, the Baldor motor has the following diagram. Never worked with 3 phase before but should each side be wired together and then tied to a line to run back? Like in the following, it looks like 1-BLU, 4-YEL, 7-PNK should perhaps all be together in a wire nut and join to one leg of 10ga wire to run back?