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Forum topic by Fargogarageguy posted 03-16-2016 05:15 PM 602 views 0 times favorited 12 replies Add to Favorites Watch
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Fargogarageguy

9 posts in 358 days


03-16-2016 05:15 PM

I recently purchased a used pm66 with a 3ph motor. I am getting 240 installed in my garage this week so I had a couple questions that hopefully someone can help me out with.
1. Is a vfd a reasonable option to convert 1ph to 3ph in order to power the saw. If so does anyone have a recommendation on a unit.

2. Would I be better off just replacing the motor with a 1ph motor. What type of motor should I look for and what cost should I expect.

3. I have no idea what type of start switch is connected to the saw. Can someone help.

I am attaching pictures of the switch, the plug, the motor, and the saw itself.

Thanks for the help


12 replies so far

View MrUnix's profile

MrUnix

4244 posts in 1666 days


#1 posted 03-16-2016 05:34 PM

What is the FLA on the motor? I use a FM50-202-c on my 3hp Baldor (7.4 FLA). The newer TECO drives have a bit more features, so you might want to consider an L510-202 which is just a bit more. Either one should be cheaper than trying to swap out the motor and having to mess with your starter.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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Fargogarageguy

9 posts in 358 days


#2 posted 03-16-2016 05:36 PM

This is the label on the actual motor. Thanks for the help

View TheGreatJon's profile

TheGreatJon

296 posts in 700 days


#3 posted 03-16-2016 05:58 PM

With a single phase motor you will need to get a new starter (the giant box with the on/off switch), new wiring, and, of course, a new motor.

With a VFD, you can just get the VFD. You would remove the starter because the VFD would act as the starter. Then you would use the existing wiring to connect the VFD directly to the motor. You do need to know the HP rating of your motor. VFDs are built for a specific range of horsepower, and you will need to get the proper size. If your motor is 5hp or bigger, the VFDs can start to get pretty expensive. At that point, it might be more cost effective to get a new motor.

You can get a new Teco VFD at any time on Ebay. You could also wait around and see if a good used one pops up. For my lathe, I got a Delta Products VFD for $80 on the bay.

-- This is not the signature line you are looking for.

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MrUnix

4244 posts in 1666 days


#4 posted 03-16-2016 06:09 PM

You do need to know the HP rating of your motor. VFDs are built for a specific range of horsepower, and you will need to get the proper size.
- TheGreatJon

Not entirely true.. size should be based on FLA, not HP… the HP rating is a marketing gimmick. Perfect example is that 3hp Baldor I have… it’s running on a VFD listed as a 2hp model, but can supply up to 7.5A to the motor. My 3hp motor only has a 7.4A FLA, so it’s well under the max rating. The “3hp” VFD can do up to 10.5A, which would be overkill, and would require lowering the overload current on the VFD (Function 18 on the FM50) to provide proper motor protection.

If you do swap out the motor, you most likely won’t need a ‘new’ starter as they are typically capable of handling either single or three phase operation. You will however most likely need to swap out the heaters in it, as they will be sized for the three phase motor which draws less current than a single phase equivalent. That appears to be a older ITE (formerly Gould) starter, so finding heaters for it might prove problematic.

Cheers,
Brad

PS: You can even undersize the VFD to a certain degree… they are capable of providing up to 150% rated FLA for a short period of time before going into overload mode. There are many people running 5hp motors on a “3hp” VFD without problems. Even though the motors FLA is over what the VFD is rated for, the motor will rarely, if ever, see full FLA.

-- Brad in FL - To be old and wise, you must first be young and stupid

View bigblockyeti's profile

bigblockyeti

3668 posts in 1188 days


#5 posted 03-16-2016 06:57 PM

Installing a new motor would almost certainly be a more expensive proposition than getting a vfd to run the motor you currently have installed. You can reuse the starter, and the wiring provided the starter can handle the current across only two legs of the contactor instead of three. In many cases installing a vfd negates the need for a starter at all.

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rick1955

258 posts in 898 days


#6 posted 03-17-2016 12:11 AM

You need to look inside the grey box. A normal switch on PM 66 is 1/3 the size of the box and it would be the same color as the saw. There’s something else in the box besides a switch.

-- Working smarter with less tools is a true crafts person...

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MrUnix

4244 posts in 1666 days


#7 posted 03-17-2016 12:54 AM


You need to look inside the grey box. A normal switch on PM 66 is 1/3 the size of the box and it would be the same color as the saw. There s something else in the box besides a switch.
- rick1955

That is a ‘normal’ switch for the PM66 :)

Inside the box is a magnetic contactor, overload heater strips and probably some terminal blocks and a control voltage transformer depending on what coil is installed. The start/stop buttons will mate with matching buttons on the front of the contactor and the whole works is known as a starter (or mag starter, or other variations of that name) There have been several different variations of starter/control station placement on the PM66 over the years, and the one shown was factory equipment for several years.

If a picture of the inside of the starter is provided, we can determine if the start/stop switch can be used for three wire control (NO start, NC stop) of a VFD or not… I’m guessing not, and s separate control station will need to be used, but without seeing the inside, it’s hard to tell.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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rick1955

258 posts in 898 days


#8 posted 03-17-2016 02:04 AM

That’s not an original issue switch. In 40 years of repairing machines I’ve never seen a PM OEM that wasn’t painted to match the saw.

-- Working smarter with less tools is a true crafts person...

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MrUnix

4244 posts in 1666 days


#9 posted 03-17-2016 02:11 AM

That s not an original issue switch. In 40 years of repairing machines I ve never seen a PM OEM that wasn t painted to match the saw.
- rick1955

Got it… granted, it’s probably a replacement for the original starter, but when you said it should be 1/3 the size, I thought you were referring to a typical LVC control station that just has the start/stop buttons and not the rest of the stuff:

Although, I have seen starters on them that were not painted to match the saw as well. Particularly during the Gould years (before the ITE buyout). The Gould starter on my PM lathe, from the factory, is painted black, similar to this:

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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01ntrain

146 posts in 537 days


#10 posted 03-17-2016 03:16 AM

It would be nice to see inside the starter-switch.

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Fargogarageguy

9 posts in 358 days


#11 posted 03-17-2016 03:21 AM

This is inside the switch

View MrUnix's profile

MrUnix

4244 posts in 1666 days


#12 posted 03-17-2016 03:33 AM

Pretty typical starter setup where the buttons on the front cover just push the ones on the contacor (see picture). That should work for single phase, but you will need to replace the heaters as they will most likely be too small (amperage wise). Finding replacements might prove a bit difficult though. If you go the VFD route, you can get rid of that starter, but you will need to find a control station (NO Start, NC Stop momentary switches) if you want three wire control, or just run it directly from the VFD front panel.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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