looking for anyone that knows anything about sawmills!! This particular saw mill has a 50 hp head saw that is wired 480 volt and some days it has great power and some days it dont. It was recently changed to 480 volt from 120/240 but was having the same problem. it seems to lose rpm's but it doesnt drop 3 to 5 volts on any leg while crowding it through a big log and the amp draw is right on with full load when in the middle of the log. Could this be an insulation problem in the motor? ANY COMMENT WILL BE GREATLY APPRECIATED!
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50 hp 480 volt sawmill problems? 1
- Thread starter bdj30
- Start date
Assuming you just meant 240V 3 phase and now it is 480V 3 phase, how is it that you changed? Did you buy a new transformer to feed it? If so, what size is the transformer? Sounds as though maybe your system capacity is not up to the task.
Yes it is also possible that you have the beginnings of a serious insulation breakdown problem. If you don't know what a megger is or how to safely use one, find someone who does and do a little testing on it. Moght be time for a rewind.
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Yes it is also possible that you have the beginnings of a serious insulation breakdown problem. If you don't know what a megger is or how to safely use one, find someone who does and do a little testing on it. Moght be time for a rewind.
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376
- Moderator
- #3
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1
- #4
Hello bdj30
Sounds to me like it could be that you have a rotor problem.
When you put the motor under load, you will increase the rotor current and the rotor bar heating.
This will cause expansion and if you have a bar break, it could go high resistance and this will increase the slip to achieve the same torque. The motor will slow without significant current rise.
I suggest that you get the rotor inspected.
Best regards,
Mark.
Mark Empson
Advanced Motor Control Ltd
Sounds to me like it could be that you have a rotor problem.
When you put the motor under load, you will increase the rotor current and the rotor bar heating.
This will cause expansion and if you have a bar break, it could go high resistance and this will increase the slip to achieve the same torque. The motor will slow without significant current rise.
I suggest that you get the rotor inspected.
Best regards,
Mark.
Mark Empson
Advanced Motor Control Ltd
- Thread starter
- #5
MiketheEngineer
Structural
My .02 cents ---- Your supply is bad?? Seen it before - often!!
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- #7
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