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VFD for 3 phase to single for Surface Grinder - Advice Please

clintnash

Plastic
Joined
Mar 2, 2022
I have purchased a 6 x 18 Chevalier surface grinder (not that is relevant but its number is FSG 618M). It has a 2.2 HP motor and is wired for 230 volt / 3 phase / 60 H.Z.. I do not have three phase in my shop and am hoping for a little guidance on buying a VFD. I would truly appreciate any advice, guidance, brand, style (if that even applies), part numbers, etc anything. This is my first venture off into 3 phase and I am out of my depth.

Thank you,
Clint....
 
You'll need a 3hp unit if your motor is 2.2hp. You dont want to undersize it. There may be some 2.5hp rated units.

You'll probably need a 220v single phase input. I dont know if anyone is making a unit that big in 120single to 220 3 phase.

Since you know nothing about it, you may want to call a local motor or electrical shop and get their advice. If you dont want to go that route, automationdirect.com has them and they have good tech support.

If you want to use the original start/stop buttons, it will take some wiring to tie that into the VFD. If not, you can use the stop/start on the VFD.
 
Does your machine have a machine light, hydraulic pump or flood coolant? If so, you need to feed all of those with three phase, not just the spindle motor.
 
You are in the 5Hp 230v ball park. This allows for rating factor due to running the VFD with single phase. You will learn about that.
Probably should buy one soon before the prices go up.

5hp vfd | 5 horsepower variable frequency drive

FYI - you don't need to derate if the drive is rated for single phase input at rated output. Smaller drives many times are. The WEG drive I posted above is rated for single phase in so no derate required.
 
Review the manual electrical schematic and match it up to your surface grinder and the motor specs. Unusual to have a 2.2 Hp motor, is it 2.2kW (3 Hp)? In either case you would need a 3Hp 240VAC single phase input VFD which is quite common. The VFD motor output needs to be directly connected to the spindle motor, so you cannot use it to power the machine and expect it to work. The schematic I looked at has the power transformer connected to the R and S terminals (single phase) and the Lubricant pump is run off the transformer (110V) singe phase. I would replace the contactor with a 24VAC relay that would latch when you press the ON button and stop breaks the power latch, use a separate set of relay contacts to activate the VFD run forward input. Not sure the need for a braking resistor in this application, the Teco L510-203-H1-N is a simple VFD and the manual is quite readable. Also the Invertek ODE-3-220105-1F42 is simple and should be easy to setup. I have heard of people using static 3 phase converters, but also reported surface issues which is because of the motor pulsations. An RPC is an option for plug and play with no modifications to the controls/wiring, you do not connect the wild leg to the transformer. Probably minimum would be a 5Hp RPC, as the surface grinder should be a light load.
Teco-Westinghouse, L510-203-H1, 3 HP, Variable Frequency Drive 230 Volt, 1 Phase Input, IP20, at Dea
ODE-3-220105-1F42 | Invertek |
 
Wow, Thank you all! I was hoping for a single response, this was fantastic. Based on the comment by metalmagpie the unit does have light, flood coolant system, DRO (which I can't image isn't 110 but who knows). I was hoping to get a jump on it while I am waiting for it to be delivered, but it sounds like the right choice is to get it (and its manual) in hand and come back with a fully formed question.

This has helped point me in the right direction in the interim to get an idea what I am looking at and provided some excellent resources.

Again, Thank you all very much!
Clint
 
I'd just buy a 1.5kw unit from one of the known makes. We get loads of used branded ones of that rating on our ebay if you don't want to fork out for new, or you could buy Chinese.

I certainly wouldnt worry about upping the rating for a home-use surface grinder you'll be very unlikely to run it at rated load anyway unless you mess up. I've been testing a (unloaded) 3hp motor with a 2hp VFD last week without a single fault.
 
I never hear people talk about how sweet a VFD is on a grinder but being able to vary the RPM can really solve some headaches as far as finish goes. I think any grinder running in a situation where anything can land on the grinding table should have a VFD.
 
There is no need/reason to under size the VFD, the cost difference between a 2 and 3 Hp is nominal. Do it right the first time, otherwise you will spend more in the long run and probably have a few headaches in the process. Get the machine in front of you first and figure out the sub systems and your comfort level for a major rewire to adapt the VFD, otherwise consider an RPC.
 
Absolutely get a VFD on the spindle. Not only can it help solve finish problems but gives you soft start capability, which can help to keep the wheel running truer without the bang start. I run my grinder on a pair of VFDs. One for the hydraulic pump motor and coolant pump, one for the spindle. The rest of the electric cabinet runs off of a single phase wall plug.
 








 
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