Big Grinder, Single Phase?

[930dreamer]

I'm looking at this grinder, seller doesn't know what size it is, data plate is unreadable. He tells me it is currently wired for 240v single phase( by an electrician) and will slowly start and build up to working speed.

I can't imagine this being a single phase grinder but who knows. I'd need to see how many wires it has.

 

[Coleman]

Looks like a BEAST!!


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[930dreamer]

I found a 10hp single phase buffer, so I guess it's possible. Would a large single phase grinder have "no capacitors"?

 

[uniballer]

I have never seen a 3 phase with capacitors but I am not an electrician.

 

[jabberwoki]

Mmmm monster grinder

 

[zkling]

Possible? Sure. Likely? Not really but What they could have done is trick wired it for single phase by putting a cap in there. Which could be an explanation of the long start time. Then again that is quite a bit of inertia to get going from a dead stop.

I'm sure APMech would know. Hopefully he will chime in.

I have never seen a 3 phase with capacitors but I am not an electrician.

Traditionally they don't, unless they have a PFC of some sort.

 

[454ragtop]

Frankly, I'll be shocked if that is in fact single phase 230 volt. Extremely rare for a grinder of that size and quality, far more likely it is 3 phase with a crappy work around or a higher voltage. If it could be had cheap enough, and was 230 volt 3 phase, would be worth buying and adding a VFD for phase conversion.
HTH, Jim

 

[3baygarage]

I thought Robocop took that thing down?

 

[Coleman]

I thought Robocop took that thing down?

Awesome! I actually laughed out loud.


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[dr_clyde]

We had one of those at a shop I worked in, 240 3 phase. It's possible that it was re jiggered to run on single phase somehow, but I doubt it. Nice grinders.

 

[exmaxima]

He tells me it is currently wired for 240v single phase( by an electrician) and will slowly start and build up to working speed.

Although this seems very strange, I can tell you my 1/2 hp Baldor 7-inch grinder takes quite awhile to get up to speed. I generally give the wheel a spin by hand before I flip the power on to save time.

 

[Outlawmws]

Does the Baldor have a starter cap? Replace it before you cook a winding...

 

[zkling]

Does the Baldor have a starter cap? Replace it before you cook a winding...

Yea a 7" grinder should almost be instantly up to speed. Run down is a different story.

 

[WWIIjeep]

Although this seems very strange, I can tell you my 1/2 hp Baldor 7-inch grinder takes quite awhile to get up to speed. I generally give the wheel a spin by hand before I flip the power on to save time.

Has it always taken a long time?

Is it a dual voltage 120/240V motor?

Are you running it on 120V when it's wired for 240V? If so, it will likely still start, but will come up to speed slowly, and will also likely have reduced power.

Not all Baldor single-phase grinders are capacitor start. The vast majority are, but some older ones are reluctance-start motors with a running capacitor instead of a starting capacitor, and those can normally take 5 to 7 seconds to reach synchronous speed from a dead stop.

 

[exmaxima1]

Not all Baldor single-phase grinders are capacitor start. The vast majority are, but some older ones are reluctance-start motors with a running capacitor instead of a starting capacitor, and those can normally take 5 to 7 seconds to reach synchronous speed from a dead stop.

It is indeed pretty old, and I just timed it: 5-7 secs is exactly right.

Seems slow compared to my Dayton 10-inch, which takes about 1 sec.