strange motor bog-down

J

John Frankl

Joined
Oct 16, 2001
Messages
1,917
Hello All,

I have a 1.5 HP Baldor from TruGrit, just like the ones on the Hardcore grinders. It is 220V and in the U.S. I could not bog this thing down.

I have relocated to Korea and it works okay here, but it is really weak and easy to bog down. In fact, I can stop it with medium-heavy pressure.

I have been given two possible reasons (though there may be more and I'd love to hear them from you guys!):

The 220V electricity is 50MhZ vs. 60 MhZ (though I don't remember which is which).

The line I ran from the breaker to the actual outlet is too small/thin. I ran Romex 12 and the distance is about 15 feet. Then there is another 6 feet of cord on the motor itself, which may be 14. Would running 10 up the power significantly?

Thanks for any and all advice.

John Frankl
 
First question I would ask is what voltage are you getting ? #12 wire is good for 20 amps, what does the motor draw ? We have 60cycle many other parts of the world have 50.
 
I don't know for sure, but I would guess that the problem could be the frequency change. AC power has a tendency to get out of phase (it follows a sine wave) when you put an inductor in the circuit (your motor). This is inneficient because you end up with a negative spot in the curve where the power is not driving the motor.
To correct this, motors have a capacitor in them and other stuff to help bring them back into phase (as close as possible anyway). The way it works out, the motor actually gets closer to phase, the more you bog it down. Since you've changed the frequency of the wave, I'd guess that your motor is either too far out of phase now, or the adjustment is wrong for it to operate efficiently.

Frequency is also what determines how fast your motor will run. By lowering the frequency, you've slowed it down. This makes me wonder if the frequency change is the entire problem though, as I know alot of guys here have set of variable frequency drives, to get variable speed. I don't know too much about how all that works out though, there might be some more that needs done to keep your power up. (this might be something to look into anyhow, so you can speed your motor back up if you want, or slow it down even more)

I don't think the size of your wire is the problem. At 220V your motor is probably only drawing about 10 amps. The 12 gauge wire should be plenty over that short of a run.

I guess the first thing I'd do is see if you can get a meter and see if you're really getting the proper voltage and amperage through the line to your motor.
 
According to a friend who deals with such things, the motor should run slower.But if yours is weaker look into the voltage .You could also check the Baldor website and ask them.
 
The motor will run at 5/6 RPM and power.
It will also run hotter, because the duty cycle of 50Hz is longer.
Reducing the voltage about 10% will keep it from burning up... :eek:
It's a no-win situation, unless you put a 50 to 60 Hz converter in-line, and these can be a bit expensive for this amount of power.
I know when we were in England, they had them available on the AF base.
See if you can round one up, so your motor will be on the type power it works best at.
 
Thanks for all the replies so far.

The motor reads that it is rated for both 50 and 60 mhz--yeah!

But where does that leave me in terms of potential problem?

Thanks again,

John
 
John Frankl said:
...I have a 1.5 HP Baldor from TruGrit, just like the ones on the Hardcore grinders. It is 220V ...l
Click to expand...
John,
After looking at TruGrit's site; is that a variable speed setup (220v controller and dc motor)?
Regards,
Greg
 
If your grinder is a variable speed DC, you can adjust the current limiter pot on the controller board to compensate for the voltage cycle difference. You should see a big difference. Also, depending on the model of the controller, it may or may not have a switch to change from 50-60hz.
 
If you contact TrueGrit they also can tell you how to adjust the screws underneath and loscated on the c/panel. You should not use a metal screwdriver as it can short out and ruin the panel. You can use a plastic screwdriver or just make you one from a popcicle stick (craft stick). This is if it is a variable speed. I exchanged the motor on mine a few years and had to do the adjustment.

R. Ramsey
 
Hello John

I asked the Motor R&D Manager here at work about your situation. The following comments are valid only if you have a single-phase, capacitor start motor.

1) A motor designed to work at 60 Hz will produce only 5/6 of the output power when run from 50 Hz. Your 1.5 hp motor is now a 1.25 hp motor. If the nameplate shows that it is rated for 50 Hz operation, then it will probably not overheat the way a 60 Hz only motor would.

2) As others have stated, check the voltage. A supply voltage that is more than a few volts below 220 V will reduce the output power. There are many local standards for supply voltage and frequency around the world.

3) If it is a capacitor start motor, you should hear a "click" as the motor gets close to it's rated speed (say 90% speed). That is the centrifugal switch that disconnects the starting capacitor. With the lower frequency, and maybe lower voltage, the motor might not ever reach the speed where the starting capacitor is switched out. Running the motor with the starting caps in circuit for a long time may burn it up.

His recommendation was to pick up a 1.5 hp motor built for the local conditions since single-phase motors are relatively inexpensive, worldwide. Hopefully your motor drives your grinder with a belt since the motors in Korea are probably manufactured with metric dimensions.

Hope this helps.

Phil
 
Thanks all.

Yes, it is a DC variable speed motor and controller all in one package. But under the stand I believe there is a plate that I can remove to adjust the trimpots. I will both check the voltage and do the adjustments.

Thanks again,

John
 
having lived in korea in the 70's id say the power supply is probably not exactly standard with the rest of the world. 220 may be oh heck 180,, that should be enough huh?
honestly things may have improved since i was there last, but i saw some pretty dim lightbulbs over there.
 
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