stalling 2hp 2x72 belt grinder

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kdnolin

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Jan 16, 2017
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I just upgraded my 2x72 i built from 1hp to 2hp. Its a WEG 1.5 kw motor i found on markeplace, but was new in box. Also got a new Huangyang 3.0kw VFD. From what i can tell, all settings are correct. My issue is, it seams to stall just as easily as my 1 hp Baldor. Can you stall your 2 hp grinders when leaning into a 2" FFG? Or could i be missing something in the VFD setup?
 
SBuzek said:
Yes you can stall a 2hp on a big flat grind on a platen.
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Maybe my expectations were too high. I just got it running last night so I just gave it a quick test and was surprised when I stalled it. I have a couple of hardened blade to grind, hopefully tonight.
 
When I was running a 2 hp 2x72 that was my #1 complaint with it.
Don’t you lose some torque with vfd’s, or am I disremembering?
 
What rpm are you running? Is this 100% speed? What size drive pulley. All those things to factor in. While it's possible to stall a 2 hp motor running wide open with all settings correct, it should be LOTS harder to stall out than the 1hp motor. Can you post a photo of the motor nameplate?
 
IIRC, there are a few parameters that relate to torque that you may need to adjust, assuming your parameters relating to your motor spec are all correctly entered (hp, rpm, voltage, etc..)
 
I tried it at 60 hz and 120 hz, 4" drive wheel, flat platen, 60 grit blaze belt, put a 3" piece of mild steel on it and leaned into it like i would normally and it slowed right down. I let it come back up to speed and checked again to make sure it was not the belt slipping, but the motor was slowing right down. i can load a pic when i get home in an hour or two. Ill also try the hardened steel, that may make a difference. Or perhaps as Drew said, could need some parameters adjusted.
 
Is your grinder direct drive or are you using a belt to transfer power from motor to drive wheel? I wouldnt expect a direct drive 2hp would stall easy.
 
One thing I noticed, I have 250v input, 280v at 60hz and 380v at 120hz on each lead
I always thought 3 phase voltage was across 2 leads. My 3 phase experience is with 480v only. 5608A34C-F5FC-44CD-A787-5091E192E977.jpeg
 
Do you have access to 3-phase? If so just run the motor without the VFD and see what happens.
My bet is you have a lemon VFD, or in best case need to adjust the parameters.
I had the same issue, changed to a "good" VFD and issue was fixed.
 
Spalted said:
Is your grinder direct drive or are you using a belt to transfer power from motor to drive wheel? I wouldnt expect a direct drive 2hp would stall easy.
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I was wondering this as well. Could it be a belt or pully slipping making you think it's running slower or can you hear the motor slowing down?
 
If you're going to ask an electrical question. We need ALL the info

Show what you have, the model numbers, the data plates, what power you're putting into it and so on.

This is especially important if you're outside North America where power standards are different from here.
 
I know this is gonna be kinda obvious, but I mention it 'cause it happened to me...

Is your drive wheel keyed, and if so is the key in place and the set screw tightened?

I changed to a bigger drive wheel and when I did i forgot to tighten the set screw. The key walked itself out and then when I applied pressure the motor would "bog down". AKA the drive shaft spun, but the wheel didn't.
 
I have missed the obvious in the past, but have some experience with motors and drives. I worked as a millwright in a sawmill for over 10 years where i worked beside electricians troubleshooting and replacing 3 phase motors from 5 hp to 200 hp, but have not experience with a VFD.

I'm in Canada, direct drive, wheel is keyed and tight. The key way does not go to the end of the output shaft on the motor, so it cannot work its way out. Everything turns freely so it is not dragging anywhere.

Power input is 220V, i have a multi meter. power input reads 124V/line, 250v together. Wired for Delta. One thing i am unfamiliar with on the motor, it only has 6 wires. most 3 phase 220/440 have 9. I am using 12 gauge single strand copper wire.

The motor works ok, it runs smoothly and quietly, but is not the improvement i was expecting. I have to lean into it fairly hard to stall it with a 2" FFG hardened AEBL, 60 grit Blaze at 60hz, at 120hz it slows down, but does not stall.

I have a loaner VFD (same brand) from Willie71, it is new, never installed. I may do a swap and see if there is any significant difference.

There is a torque setting in the VFD, pd145, factory setting is 2.0, max is 10.0, I changed it to 3.0 and it helped. Manual says to adjust this incrementally, is anyone familiar with this setting?

I see the downside to a cheap VFD is customer support does not exist!
 
Torque vector is likely a setting to adjust rotor/magnetic slip. Higher slip should produce more torque but increase current which can increase motor temps. I would try turning it up even more.

Make sure you have the drive set up for variable torque and not constant torque. Check your acceleration setting and reduce it if needed. Sometimes this can reduce torque if the motor is loaded down so it's rpm drops, then it is slow to ramp back up because low acceleration time. Lastly make sure your motor current in the drive is correct. If it's set too low it will act like a lower HP motor
 
Backyard said:
Torque vector is likely a setting to adjust rotor/magnetic slip. Higher slip should produce more torque but increase current which can increase motor temps. I would try turning it up even more.

Make sure you have the drive set up for variable torque and not constant torque. Check your acceleration setting and reduce it if needed. Sometimes this can reduce torque if the motor is loaded down so it's rpm drops, then it is slow to ramp back up because low acceleration time. Lastly make sure your motor current in the drive is correct. If it's set too low it will act like a lower HP motor
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This may be the problem, it ramps up slow, probably 10 seconds from stop to full speed at 120hz and slows down the same. I haven't figured out the setting for this yet, could be an issue.
 
Which Chinese VFD do you have? They are not all created equal by any means. Some are MUCH easier to setup than others. I've used several of them with good success. I agree, 6 leads from a 3ph motor is not something I'm familiar with. There are 12 leads for a typical 3 ph motor, 3 of which are normally tied together inside motor leaving 9 leads outside in peckerhead.

As mentioned before, can you do an amp reading on motor, both idling and under load?
 
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https://www.amazon.ca/Variable-Frequency-Inverter-Converter-HUANYANG/dp/B0775GRPFJ
This is a link to the VFD. The loaner i got from Willie71 is the same brand, but 1.5kw. I hooked it up last night, programmed it and the performance was the same. so i think i have ruled out a faulty VFD. I watched a few videos on programming this specific VFD, studied the manual cover to cover and believe all settings are correct. The display does give amp readings and no load amps are about 1.5 - 1.6, I did not check amps while it is stalling. Something I'll definitely check.

After using it a little more last night I can tell that it does have more power than the 1hp, but I am beginning to think I either have a low torque motor or expectations were too high.
 
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