Automatic surface grinder and vfd

Ryan Minchew

Ryan Minchew

Joined
Sep 29, 2005
Messages
580
Has anyone ran an automatic surface grinder using a vfd? I know they will run a manual one fine, but maybe issues with other switches on automatic machines. There's a hydraulic pump, coolant pump, and an oiler pump on this machine besides the spindle motor wondering if I should build a rotary phase converter instead? This is for a harig automatic.
 
I run my auto surface grinder from a VFD, but it's mechanical feed and the coolant and mag chuck are run from single phase plugs of their own.
If your machine takes only the one big power 3-phase power lead to the wiring box, then splits smaller circuits off to the pumps, I think it would be fine as long as your VFD is rated for the combined amperage. I view my VFD as basically a 3-phase power source, up to a certain amperage. I have a mill for instance that has a 3 phase power feed motor, and I run the feed motor and spindle motor together with no problems.
I don't know what VFD you have, my Teco FM50 has proven to handle combined loads without damage.
 
Find out what the power needs are for the ancillary motors. Just because a machine needs "3 phase", does not mean all its motors are 3 ph.

You may have to reconfigure its control box to connect just the wheel motor to VFD.
Then if needed use another non VFD 3Ph converter to power the ancillaries. But a good chance those small motors are single phase.
 
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If the machine takes a single three phase power input, and then splits a leg off to power a separate single phase motor, it shouldn't change the basic power requirement of the machine overall, i.e. 3 phase 220 volts 10 amps... but the machine will then be wired with a neutral as well as a ground (wye as opposed to delta). If you see that the pump motors are single phase, then it is likely you will see a neutral wire in the machine's power tail, to allow 120v single/split phase applications to feed from it. Your VFD will be supplying delta 3-phase, i.e. no center-tapped neutral to allow one leg to supply single phase.
If the pumps are not fed by the same 3 phase input as the spindle motor, and are single phase, then you will see separate plugs for them.

If your machine needs 3 phase wye with a neutral to supply everything from a single source, then you could use the delta 3 phase put out by your VFD to directly feed the motor, and then disconnect the single phase pumps from the machine circuits and power/switch them separately to a single-phase source in your shop.
 
Salem Straub said:
If the machine takes a single three phase power input, and then splits a leg off to power a separate single phase motor, it shouldn't change the basic power requirement of the machine overall, i.e. 3 phase 220 volts 10 amps... but the machine will then be wired with a neutral as well as a ground (wye as opposed to delta). If you see that the pump motors are single phase, then it is likely you will see a neutral wire in the machine's power tail, to allow 120v single/split phase applications to feed from it. Your VFD will be supplying delta 3-phase, i.e. no center-tapped neutral to allow one leg to supply single phase.
If the pumps are not fed by the same 3 phase input as the spindle motor, and are single phase, then you will see separate plugs for them.

If your machine needs 3 phase wye with a neutral to supply everything from a single source, then you could use the delta 3 phase put out by your VFD to directly feed the motor, and then disconnect the single phase pumps from the machine circuits and power/switch them separately to a single-phase source in your shop.
Click to expand...

I am almost positive the coolant and the hydraulic pump plug into a 110 outlet on the back of the machine. So if I use a vfd I canNOT use those plugs? Did I understand that correctly? The way oiler comes on when the spindle motor is turned on, I will have to see how that's done. I appreciate the help. I can wire a vfd to the machine but that's about the extent of my electrical know how.
 
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I would just plug the coolant and hydraulic into whatever 110V circuit you have available in your shop, not into the machine's outlet. Your don't have a neutral wire in your VFD power supply for single phase to return with.
If the way oiler has a single phase motor, then power that the same as your coolant and hydraulic.
As long as the way oiler is either 3 phase or disconnected from the spindle power supply, you should be able to just take the three hot legs and ground from your VFD and run it to the existing three power lugs and circuitry, without trashing anything, just to power the spindle. Or, you could wire the VFD straight to the spindle, bypassing the motor starter and other circuits.

The idea is to identify absolutely anything on the machine that might be single phase, and power it separately from the spindle power supply.
Like I say, my coolant pump and mag chuck are wired 110V single, and plug in separately from my 3 phase spindle/table feed motor, and my machine uses a one-shot oiler for the ways so no motor there.

Oh, and don't shock yourself. I was a big dummy on my recent lathe project and got hit by one leg of my Phase Perfect, quite a jolt and to be avoided. It is always a possibility unless great care is taken...
 
Thanks Salem. Should be here tomorrow but wont be able to move it from garage to out back in the shop with help of friend and tractor for a bit to mess with it.
 
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