steve708
Member
Lots of automotive plants running slow these days, consequently the large 6" chain conveyor systems are called upon to run at very slow rates. We have either AC or DC adjustable speed drives on many of them and are looking to convert many more of them from fixed speed to allow for maximum flexibility going forward.
We need between a 3 to 1 and 4 to 1 speed range on most conveyors and this is pushing the limits of motor capabilities, at least the AC ones. I would consider 20Hz the low limit, we may need to go slightly above 60 Hz in the future.
The AC motors are old Delco 7EH spec non-inverter duty NEMA Design B TEFC and are being run with Reliance or AB VF drives. The DC motors are old Reliance compound wound 240V types being run with old Reliance or AB DC drives.
I am looking for opinions on the long term effects of running AC and DC conveyor motors for 10 hours a day 4 days a week at 500 to 600 RPM. Changing the sheaves or reducers is not an option because we would like to get the right combination to achieve the 3 or 4 to 1 speed range and not have to change them again.
I also need to mention that all of these conveyors are mechanically oversized as far as motor horsepower goes. None of them ever draw more than half of their full load current in normal operation, most are at one third or less.
Thanks in advance!
We need between a 3 to 1 and 4 to 1 speed range on most conveyors and this is pushing the limits of motor capabilities, at least the AC ones. I would consider 20Hz the low limit, we may need to go slightly above 60 Hz in the future.
The AC motors are old Delco 7EH spec non-inverter duty NEMA Design B TEFC and are being run with Reliance or AB VF drives. The DC motors are old Reliance compound wound 240V types being run with old Reliance or AB DC drives.
I am looking for opinions on the long term effects of running AC and DC conveyor motors for 10 hours a day 4 days a week at 500 to 600 RPM. Changing the sheaves or reducers is not an option because we would like to get the right combination to achieve the 3 or 4 to 1 speed range and not have to change them again.
I also need to mention that all of these conveyors are mechanically oversized as far as motor horsepower goes. None of them ever draw more than half of their full load current in normal operation, most are at one third or less.
Thanks in advance!
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