My problem is: brand new 2 hp 208 230 3 phase motor is drawing 7.1 amps under load 4.1 amps under no load. Data plate says it should be drawing 6.1 amps. Our service is 240 Delta. Will drawing 7 amps cause an early demise to the new motor? It is powering an air compresssor which was powered by 2hp motor originally. Motor starts ok and seems to run ok. It has only been run for 6min or less a few times.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
motor issue
- Thread starter newbydave
- Start date
- Joined
- Jun 7, 2013
- Messages
- 10,071
Sounds like the motor is overloaded, running on 240V the amps should be a little less than the FLA stated on the nameplate. It may be a good idea to change the motor pulley to a smaller size in proportion to the overload amount. With an intermittent on/off cycle you might get away with the overload, but if it runs a lot, maybe not.
- Joined
- Apr 30, 2015
- Messages
- 11,248
Does it run real hot? If not I wouldn't be too concerned
If the temp rise is within spec on the nameplate you are OK
If the temp rise is within spec on the nameplate you are OK
- Joined
- Mar 29, 2017
- Messages
- 737
Indeed. My air compressor from the late 40's has a GE motor rated at 2 HP. It is as big as a 5 gallon bucket in diameter, and nearly as long. It weighs 100 lbs at least, and draws far north of the amperage the book says makes 2 horse power. Were the horses "Clydesdales" back then, and now they are "Shetland", or whatever breed of pony Genghis Khan used?
- Joined
- Apr 27, 2017
- Messages
- 10
What is the S.F. (service factor) of the motor, or are you including that to get your 6.1 amp?
Most newer motors for equipment are designed to be able to run at higher loads for short periods of time. It should be able to run at that amp draw for at least the 6 minute bursts, as long is it has enough time to cool between cycles. Like Mark said above, as long as it does not get too hot it will be fine.
Most newer motors for equipment are designed to be able to run at higher loads for short periods of time. It should be able to run at that amp draw for at least the 6 minute bursts, as long is it has enough time to cool between cycles. Like Mark said above, as long as it does not get too hot it will be fine.