I have a 3 phase 3hp Mill that I am trying to run on a 5hp WNY static converter. The mill starts and runs fine but is tripping the heaters in the mag starter after a few minutes of light use. I let it cool, reset the starter and it trips again after a minute. The heaters are labeled B15.5. Are these the right heaters or what else may the problem be? Should I just break down and buy a VFD for it? I included pictures of the motor plate and starter. Thanks
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Mill with static convertor shutting down
- Thread starter kingchevy
- Start date
metlmunchr
Well-known member
- Joined
- Sep 10, 2011
- Messages
- 1,289
Heaters appear to be the right size based on motor nameplate amperage.
A static converter is the fastest device ever invented for burning up a machine tool motor. The typical vertical mill motor is a special motor due to shaft configuration, and replacements are seriously expensive.
A friend bought a new horizontal bandsaw with a 2hp 3 phase motor in anticipation that he would move out of his single phase only garage and into a building with 3 phase power in the future. In a year's time he fried 2 motors with a static converter, and the third one burned up shortly after he moved to a location with 3 phase power, indicating the static converter was on the verge of killing that one prior to the move.
That was in the late 90's, and he still runs that saw daily with no further motor problems.
A VFD would be a very good investment for that mill.
A static converter is the fastest device ever invented for burning up a machine tool motor. The typical vertical mill motor is a special motor due to shaft configuration, and replacements are seriously expensive.
A friend bought a new horizontal bandsaw with a 2hp 3 phase motor in anticipation that he would move out of his single phase only garage and into a building with 3 phase power in the future. In a year's time he fried 2 motors with a static converter, and the third one burned up shortly after he moved to a location with 3 phase power, indicating the static converter was on the verge of killing that one prior to the move.
That was in the late 90's, and he still runs that saw daily with no further motor problems.
A VFD would be a very good investment for that mill.
wyliesdiesels
Well-known member
Static converters are ****.
They start motor powered on all 3 legs then drop out one leg and single phase the motor.
My guess is the voltage is low causing the current usage to go up and thus tripping the overloads
EDIT: do you have a clamp meter you could use to test the current draw on each leg? Also test the voltage.
Without the ability to do so metering, you wont be able to figure out much here.
They start motor powered on all 3 legs then drop out one leg and single phase the motor.
My guess is the voltage is low causing the current usage to go up and thus tripping the overloads
EDIT: do you have a clamp meter you could use to test the current draw on each leg? Also test the voltage.
Without the ability to do so metering, you wont be able to figure out much here.
Last edited:
Falcon67
Well-known member
I've always "heard" that a static has to be at least double the size of the load. I would consider a 3 HP VFD in place of that static unit, if possible.
wyliesdiesels
Well-known member
Thanks for the replies. I don't want to risk smoking the motor, I'm going to get a VFD.
Do you have a clamp meter?
Do you have a clamp meter?
No, but I could get one. I checked the voltage at the machine while not running and it was 246v.
wyliesdiesels
Well-known member
No, but I could get one. I checked the voltage at the machine while not running and it was 246v.
checking voltage with no load means very little...