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Powermatic 72 Table Saw with Teco A510 VFD

caryd12

Plastic
Joined
Feb 22, 2018
I just purchased a 1980 model Powermatic 72 table saw which has a 5hp 3ph Baldor (184C frame, Des B, Class F)

I have dedicated 200 amp single phase service in my home shop so I needed a way to power the saw from that. I've had less than stellar results with single phase motors over 3hp at my day job (air compressor and vacuum pump service) so I wanted to find a way to keep the 3 phase motor installed on the table saw. I got the Teco A510-2010-C3 VFD on the advice of tech support from one of the major online retailers for VFD drives.

My question is regarding the start stop switch for the saw, the saw already has a starter box with start / stop control on it however it is 3 phase. I know the VFD has to be connected directly to the motor and the start / stop buttons on the VFD controller are quite small and not ideal for a table saw application in my opinion. It looks as though there are two ways of accomplishing adding another start / stop controller but I wanted to confirm that I am on the right path:

1.) install a single phase start / stop button downstream of the breaker and upstream of the VFD. In this case the VFD would need to have auto-restart option turned on so that it would automatically power on when power is applied.

2.) the VFD has digital inputs for FWD / Stop (also has REV/ Stop but I don't believe I would need that for my application). To use this digital input what exactly would I need? Most of the control panels I deal with have single VFDs being controlled by a PLC that sequences several motors, so this application is a bit different for me.

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caryd12,

Welcome to the forum.

If you wanted to keep your existing START/STOP button location and function you could outfit the mag with a 120 volt coil, power it from a convenient nearby outlet and use the contacts on it to switch the logic circuit on the VFD.

I don't know if the A510 has the appropriate factory electronics to allow a momentary input to be configured as maintained. I have used a small DPDT relay on a TECO FM series inverter to allow latched, 3 wire control for a machine which is what you're trying to achieve on the table saw.

Marshall Wolf Automation, a TECO distributor, supplied the schematic on wiring up the DPDT relay.

Look in the manual that came with the drive for '3-wire control'.

I have a 5hp Unisaw running on static converter which works well..the one thing I did and I would recommend is adding a large paddle style STOP button actuator that's in a accessible location for that inevitable moment when you need it.:eek:

If the addition of an external relay is required for latching purposes in your instance..and just for grins, I'll tag on the wiring example that was sent to me by the TECO rep.

Stuart


teco4.jpg
 
If you simply put a cedarburg start box on it, you'd get 3/4 of the h.p.
that would make it 3.75 h.p.

Adding some balance (run) caps might just be good enough
 
So after talking to tech support at Marshall Wolf Automation (which is incidentally where I got the A510 drive) they recommended going with the two wire setup for simple start / stop control. McMaster-Carr sells a 2-wire start/stop switch that is the emergency stop style and is maintained so you pull it on and it stays. I’m going to try to make this work for now as it is a quick and cheap way to get going. The 3 wire would be required if I wanted to keep the existing start stop however I like the idea of removing it and installing a panel to house the VFD and start / stop switch in that spot.

Is there any other advantage to having separate start / stop buttons that I’m missing?
 
If that's the route you're going to take right now, and you plan on putting the drive in an enclosure mounted to the saw then if it were me..which it isn't, I would use one of these Paddle Switch 12/23V | Grizzly Industrial in a 2"x4" plastic bell box mounted near the front of the saw. These are Chinese switches but the are a simple ON/OFF maintained operation with the benefit of the big fat paddle.

I built a paddle for my saw and I can hit it with my upper thigh and shut the say off if my hands are busy..very handy. Mount the switch in a handy location, run the cord to the enclosed drive and 'Bob's your Uncle'.


The only caveat is that with a maintained ON switch, any trip of the drive, whether it be a fault or power failure will result in a saw start up on trip reset or resumption of power.


Stuart
 
caryd12,

If you look at page 7-3 of the online manual for that drive they describe quite clearly how to wire the unit up for 3 wire, momentary pushbutton control. Every drive is different, newer drives have more features and the distributor can't always be relied on to know all the intricacies of each and every drive.

Stuart
 
the downside to a "2 wire" on-off control strategy is that if power fails, the saw will stop, but when power comes BACK, the saw will AUTOMATICALLY restart. That is potentially very dangerous. What a Start/Stop "3 wire control" circuit does is that if the power fails, the circuit drops out and when power is restored, you will need to hit the Start button to re-start it.
 
the downside to a "2 wire" on-off control strategy is that if power fails, the saw will stop, but when power comes BACK, the saw will AUTOMATICALLY restart. That is potentially very dangerous. What a Start/Stop "3 wire control" circuit does is that if the power fails, the circuit drops out and when power is restored, you will need to hit the Start button to re-start it.

That concept was explained in the post right above yours..did you not notice it??

Stuart
 
That’s a good point about the automatic power restart danger, I think there is a programming setting within the VFD to have it to restart or not after power failure as well
 
That’s a good point about the automatic power restart danger, I think there is a programming setting within the VFD to have it to restart or not after power failure as well

There is that programming feature..but regardless, if you program NOT to auto reset on a trip but have to manually reset, it will still make the saw jump to life if the maintained ON button has not be switched to OFF.

Stuart
 
That concept was explained in the post right above yours..did you not notice it??

Stuart
The post right above mine says nothing of the sort.
If you look at page 7-3 of the online manual for that drive they describe quite clearly how to wire the unit up for 3 wire, momentary pushbutton control. Every drive is different, newer drives have more features and the distributor can't always be relied on to know all the intricacies of each and every drive.

Maybe the manual page you referenced explains WHY you want to use 3 wire instead of 2 wire, but I didn't read that manual. I just answered the guys question.
 
Sheesh...OK, you win..two posts above your post! I usually read an entire thread and try not to duplicate what has already been expressed, maybe I'm a sap for doing it that way but it tends to keeps the redundant clutter out of the thread...sort of like putting Thermite on 'ignore'!

Stuart
 
One more question on this setup (I think), as far as sizing the feeding breaker for the saw with VFD what amperage should I be sizing for? The VFD has a rating of about 34 amps but that is 3 phase. I am going to be de-rating the drive for running a 3 phase 5 hp motor. So what does my main breaker feeding all of this need to be?
 
caryd12,

It's probably spelled out in the manual that came with your drive, but it's common to size the breaker to 125% of the input current rating of the drive. Make sure your wire size is proper for the circuit and the circuit protection.

Keep in mind that the breaker is protecting the drive while the drive itself is programmable to protect the motor from overloads.

Stuart
 
Sheesh...OK, you win..two posts above your post! I usually read an entire thread and try not to duplicate what has already been expressed, maybe I'm a sap for doing it that way but it tends to keeps the redundant clutter out of the thread...sort of like putting Thermite on 'ignore'!

Stuart

sap?, that's putting it mildly...

"tends to keeps" ---> "tends to keep"....

Thermite might have annoying humor, but you are .... :nutter:

I understand it. Have been to Eureka several times. The highest paid profession is carving bears and pelicans out of redwood stumps using chainsaws. :willy_nilly:
 
sap?, that's putting it mildly...

"tends to keeps" ---> "tends to keep"....

Thermite might have annoying humor, but you are .... :nutter:

I understand it. Have been to Eureka several times. The highest paid profession is carving bears and pelicans out of redwood stumps using chainsaws. :willy_nilly:

Ronzo,

You just gotta quit following me around...I'm starting to wonder about your intentions. I'm married and don't fool around with guys, especially guys like you.:nono:

Pelican Boy
 
Caryd12:
I had to put a VFD on my table saw. It came with a magnetic start stop switch. I put the VFD on the output of that, and added a 2 wire stop start switch (same one that atomarc linked in post #5).
This way with power outage, there is no way to auto restart.
In my case I have a 14" saw with a 7.5HP motor. I used a Teco MA7200 10Hp VFD. I've never exceeded the power it delivers, with my toughest task of ripping 2x4s into 2x2s.
 








 
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