losing motors

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tw/nci

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hey guys, I was wondering if I get some input on a problem that I am having with a motor on a pnuematic air compressor. The original motor is a Baldor motor 115V/230V, 2HP, single phase. Every few months the back bearing fails. The motor repair service says that at some point the motor is looking for more HP and it is cycling on the centrifugal switch, which arcs to the bearing. I changed the motor last time and went to a Dayton 2 HP motor. I lost 2 motors in about 1.5 weeks. I now have a temporary C-aire compressor plugged in to a convenience outlet and that motor has held up but trips the breaker every few days. I have attached a log recording which portrays a 3 day snap shot with the temporary compressor on line. Thanks in advance for any help.:-?
 
tw/nci said:
hey guys, I was wondering if I get some input on a problem that I am having with a motor on a pnuematic air compressor. The original motor is a Baldor motor 115V/230V, 2HP, single phase. Every few months the back bearing fails. The motor repair service says that at some point the motor is looking for more HP and it is cycling on the centrifugal switch, which arcs to the bearing. I changed the motor last time and went to a Dayton 2 HP motor. I lost 2 motors in about 1.5 weeks. I now have a temporary C-aire compressor plugged in to a convenience outlet and that motor has held up but trips the breaker every few days. I have attached a log recording which portrays a 3 day snap shot with the temporary compressor on line. Thanks in advance for any help.:-?
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See the bold part of the quote..what kinds of drugs are the motor shop guys smoking? "The motor is LOOKING for more horsepower and cycling on the switch which arcs to the bearing? " :roll:

The problem is a simple one: Either the frame of the motor is not properly grounded. Make sure there is a grounded conductor (NOT the flex or EMT) connected all the way back to the panel.

OR:

If you haven't already, change the drive belt. An old, dry belt will build up tremendous static charges which can easily arc up a bearing.

And as for the Dayton motor: did you get the one SPECIFICALLY rated for air compressor duty? You cannot just stick any old motor on an air compressor...compressor motors are designed to have extra starting torque and are able to stand up to the FREQUENT starts that a compressor subjects a motor to.

Finally, most compressors "HP" ratings are a big marketing ploy. Ever notice how you can get a "5HP" compressor that plugs into a 15amp recept? Do the math and you'll see that to create 5HP of energy even at 100% efficiency is not possible with 15 amps at 120 volts.
 
mxslick said:
Finally, most compressors "HP" ratings are a big marketing ploy. Ever notice how you can get a "5HP" compressor that plugs into a 15amp recept? Do the math and you'll see that to create 5HP of energy even at 100% efficiency is not possible with 15 amps at 120 volts.
Click to expand...

i heard that HP rating on the compressor is how much power it will handle right before it breaks. i never seen an HP rating on a compressor motor just amperage
 
I would be looking at an alienment problem or wrong motor for the size compressor-not electrical if properly grounded.
 
could the belt be too tight? that could put some wear and tear on the bearings. when i put belts on pulleys i like it to have a little play. i dont want it to be loose but i also dont want it to be tight as a banjo string. i want it to move when i wiggle it
 
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