Can a 3-phase on/off switch be wired for 1-phase?

[rust buster]

I took a gamble and picked up a Baldor 1216W 12" pedestal grinder on ebay a few months back, which is 3-phase. I wired it up today with a Teco L510 VFD and it runs smooth as silk. I'd like to make a control station with remote start/stop, emergency stop, and speed controls wired to the VFD, and put an on/off switch upstream (between the VFD and the incoming power). The reason is so that I don't have to keep unplugging the VFD to turn it completely off. The grinder came with a very nice Allen Bradley On/Off switch, which of course is wired for 3-phase. Is there any way to keep this and use it as my on/off for power to the VFD (single phase 230V), by not connected one leg or something?
Let me know if I am making any sense....

 

[micromind]

That switch is a manual motor starter. It has an overload relay and heaters. The heaters are the small black things that have W49 marked on them. In this case, if the current goes higher than 9.1 amps, it'll eventually trip. The higher it goes, the quicker it'll trip.

But yes, this starter can be used with single phase, just pick any 2 of the 3 legs.

 

[TurnipTruck]

As long as the starter coil sees the voltage it needs.

 

[wyliesdiesels]

I would remove the heaters if youre gonna use that

 

[micromind]

I would remove the heaters if youre gonna use that

That works on a lot of starters but the Allen Bradley ones need all 3 heaters installed in order to be reset and then turned on.

If the heaters are too small, any heater up to W58 (21 amps) can be installed.

The heaters are readily available on eBay.

 

[Doozer75]

There are no 3 phase switches.
There are however 3 pole switches.
In which case, you can use the poles for anything
withing their current rating.

-Doozer

 

[LopezBart]

Use the switch contacts to control on-off on the VFD. You'll want/neeed a disconnect within visual distance; the breaker works fine as long as it's close. Look in your VFD manual; it will have the details on how to program the VFD to use momentary contact buttons.

 

[W-Cummins]

Hook it up and see what happens. What is the full load amps of VFD?? The installed heaters are under sized for single phase ( would use #57 ) but if your soft starting the grinder, and not hogging the **** out of it, it might be ok (and it will just shut off if not).

William....

 

[rust buster]

Thanks for all the info. This is a 2HP VFD I'll have to take a look at the motor plate when I get back to it.
I'll hook it all up and see what happens...

 

[fitter30]

Model and brand of vfd?

 

[micromind]

Thanks for all the info. This is a 2HP VFD I'll have to take a look at the motor plate when I get back to it.
I'll hook it all up and see what happens...

It's not the motor current, it's the input current of the VFD.

If the haters are too small, the worst thing that can happen is the switch will trip and the motor will stop. If it does, it takes a minute or so until it can be reset.

I doubt if it'll trip even if the heaters are too small. The motor will very likely not be run at full load current long enough to cause a trip.

 

[rust buster]

It's a Teco L510-202-H1-U.

 

[loganb]

I just did something kinda similar on a vfd conversion. I was looking for a way to kill line power into the vfd for the same reason and thought about reusing an old motor starter, instead opted to use this 3 pole rotary disconnect and just don't use one of the poles:

https://www.digikey.com/en/products/detail/b-j-usa-inc/LTS20-EHN4-A3/14556750?_gl=1*kv11ij*_up*MQ..&gclid=CjwKCAjw17qvBhBrEiwA1rU9w5wQRCrtFySJ_EUcamW29k0JnWn6vCr53u2td8Hv5F904cyT9APPvxoCajAQAvD_BwE

I was looking for a disconnect that could fit in a particular space to make it easy to access for me...without that space limitation there are cheaper ones that could be used. More details and some pictures are on the last page or two of my thread in the signature here as I posted several updates over the weekend

 

[rust buster]

test

 

[rust buster]

I just did something kinda similar on a vfd conversion. I was looking for a way to kill line power into the vfd for the same reason and thought about reusing an old motor starter, instead opted to use this 3 pole rotary disconnect and just don't use one of the poles:

https://www.digikey.com/en/products/detail/b-j-usa-inc/LTS20-EHN4-A3/14556750?_gl=1*kv11ij*_up*MQ..&gclid=CjwKCAjw17qvBhBrEiwA1rU9w5wQRCrtFySJ_EUcamW29k0JnWn6vCr53u2td8Hv5F904cyT9APPvxoCajAQAvD_BwE

I was looking for a disconnect that could fit in a particular space to make it easy to access for me...without that space limitation there are cheaper ones that could be used. More details and some pictures are on the last page or two of my thread in the signature here as I posted several updates over the weekend

That's a great idea and you made it look like it came like that. I have going to be doing the same thing with a Clausing drill Press I picked up and may steal this. Thank you!

 

[rust buster]

I'll let everyone know if successful

 

[OccupantRJ]

I installed a switch for each of my two L510 vfd, but found that I stopped turning them off in a few days. The have been on 24/7 for about 6 years now.

 

[alfredeneuman]

You're required to have a disconnect ahead and within sight of the VFD.
A 2 pole toggle switch with the proper HP rating could be used with a lockable cover.

 

[LopezBart]

You're required to have a disconnect ahead and within sight of the VFD.
A 2 pole toggle switch with the proper HP rating could be used with a lockable cover.

A breaker will suffice if visible from VFD. Lockable isn't necessary for home use.

 

[loganb]

You're required to have a disconnect ahead and within sight of the VFD.

By what? If this is plugging into a receptacle, NEC shouldn't apply based on my understanding. Is it good practice...yes, but not aware of a code mandate for it

 

[LopezBart]

A plug is a reasonable disconnect for home use.

 

[micromind]

The OPs switch has a lockout feature.

There's a small white tab on the right-hand side of the pushbutton and another black one just above it. With the switch in the off (stop) position, hook your fingernail in the black tab and pull it out. It has a hole for a padlock. When it's locked out, the start button is disabled.

 

[rust buster]

By what? If this is plugging into a receptacle, NEC shouldn't apply based on my understanding. Is it good practice...yes, but not aware of a code mandate for it

Yes, right now, the VFD is plugged into a receptacle right behind the grinder

 

[W-Cummins]

So I was looking at your grinder if it is really a 3hp model and not the 2hp version, Not only are the heaters undersized, your VFD is too!

 

[fitter30]

3.9 page for stop/start

https://www.google.com/url?q=https://www.tecowestinghouse.com/Manuals/L510_instruction_manual.pdf&sa=U&ved=2ahUKEwiv18K-g_SEAxUv78kDHXLNBBYQFnoECAsQAg&usg=AOvVaw155KL7UQIZgd8GjOIzQl2s

 

[rust buster]

So I was looking at your grinder if it is really a 3hp model and not the 2hp version, Not only are the heaters undersized, your VFD is too!

That Allen Bradley switch is what came from the factory on this grinder from Baldor. I mistyped the VFD, I gave the P/N for the on I bought for my Clausign drill press. The one for the grinder is L510-203-H1-U

 

[W-Cummins]

Please post up the motor id plate from the grinder, was it set up to run at 460V?? That would make since, if it is a 3hp model running the installed heaters. BTW what happened when you tried to run it with the existing heaters?

 

[rust buster]

Please post up the motor id plate from the grinder, was it set up to run at 460V?? That would make since, if it is a 3hp model running the installed heaters. BTW what happened when you tried to run it with the existing heaters?

Yes, it came set up as 3Ph 460V. I'll send a picture of the motor this afternoon, hopefully. I have not had a chance to try and run it with the heaters yet.

 

[W-Cummins]

Well that changes things..... The current heaters are just shy of 3X too small. You could still try it, but it will not take much to shut it off. So.... if you want to use the switch I would take out the heaters and crimp two suitable ring terminals on the hot leads ( if the wire is stranded, if solid wire you could prep the wire like you are going to wire it under a screw on an outlet) and land them under two of the 3 screws (poles) that are closest to the push buttons and by pass the heater block. I would probably choose the the right and left side poles ( and not use the center screw/pole) to get the largest separation of the 2 hots. You could also get larger heaters (W60), but they are not really being used, as your supposed to set the over current protection on the VFD.

William....

 

[micromind]

That switch cannot be turned on with no heaters.

Just replace them with W58s.......usually available from eBay.

Then the switch will handle up to 21 amps.

 

[W-Cummins]

That switch cannot be turned on with no heaters.

Just replace them with W58s.......usually available from eBay.

Then the switch will handle up to 21 amps.

Well.... My switch has no problem running w/o the heaters installed, W58 are not good for 21 amps, and his switch isn't either! I failed to notice the * and read it for the w58 heaters ( says that they are the max size for his switch size 0). So my suggestion for running size W60 is wrong! Also the size 0 is not rated for 3hp @ 230v single phase, interesting is that my switch is a single phase size 1 its label only shows 3 phase ratings! Shame on you A&B.....

 

[micromind]

That type of switch (Allen Bradley 609) will feel like it's operating normally without heaters but the contacts are not actually closing in.

The HP rating applies only to turning motors on and off. For non-inductive loads, the amp rating applies.

The size 0 switch is rated for 18 amps but 21 absolute max.

The trip current is 115% of the heater rating as listed in the chart. More than 115% and it'll move toward tripping. At 120%, it might hold for 10 minutes, at 600%, it'll trip in 20 seconds.

The J type heaters are class 10. This means that they'll trip within 10 seconds at 600% of the rating. The type W are class 20......20 seconds @ 600%. The type WL is class 30. 30 seconds @ 600%.

 

[W-Cummins]

That type of switch (Allen Bradley 609) will feel like it's operating normally without heaters but the contacts are not actually closing in.

Yep Sure that's why the meter shows 000.3 ohms across the switch!

 

[alfredeneuman]

A breaker will suffice if visible from VFD. Lockable isn't necessary for home use.

Can you provide a Code citation for that?

 

[Norcal]

Can you provide a Code citation for that?

Somewhere in the Urban Legend Code.......

 

[alfredeneuman]

Somewhere in the Urban Legend Code.......

That pesky ULC strikes yet again

 

[wyliesdiesels]

A breaker will suffice if visible from VFD. Lockable isn't necessary for home use.

oh really? why not?

 

[LopezBart]

If the disconnecting means is within sight (and 50' apparently) of the device to be disconnected, a locking disconnect is not required. I believe OSHA regs require lockable disconnects & tagging, etc, but that is not home use. Note the use of the word
"or" in 422.31:

422.31
(B) Appliances Rated over 300 Volt-Amperes.
For permanently connected appliances rated over 300 volt-amperes, the branch-circuit switch or circuit breaker shall be permitted to serve as the disconnecting means where the switch or circuit breaker is within sight from the appliance or be capable of being locked in the open position in compliance with 110.25.

 

[wyliesdiesels]

But earlier you said it wasnt necessary.

 

[LopezBart]

But earlier you said it wasnt necessary.

What I said was:

A breaker will suffice if visible from VFD. Lockable isn't necessary for home use.

I realize that if you decide to ignore the first sentence, this isn't right. How about:

"A breaker or switch will suffice if it is visible and within 50' from the VFD; a lockable breaker/disconnect isn't necessary for home use if this condition is met, but may well be required by other safety regulations such as OSHA that apply in commercial/industrial scenarios."