Originally Posted by bilinghm  The motor is a Leeson catalog number G120088.00, 2 pole 3600 rpm fully enclosed fan cooled. The drive is a Hitachi SJ200 sensorless vector drive.
So If I understand correctly, the recommendation is to select a belt setting that produces the slowest usable speed at around 25-30 cycles and overspeeding the motor to achieve the top RPM range? I called Leeson and they said that this motor is designed for VFD use and is normally usable from 6 to 60 cycles with no danger of overheating. They also reccommended that the upper limit be kept to about 75 cycles. |
Then go with there recomendation, thats sounds like an IRIS motor(is it black?), although its been some 5 years since I worked for them, 75 cycles sounds more like a bearing limit then a motor limit per say. I would go with 25 as the real low end unless you can deal with not so smooth running and low torque, although it maybe handy to run below that for indicating and such. Its not an exact science unless you have them do a matching, I only did that once when I was in the lab and it was little more then an engineer pulling 3-5 motors he thought would work, then test results dictated what he picked or a range of such. Many of there older motors predate accurate tests and I was in the process of testing alot of older motors for CSA and UL for standards, welll that was untill the 9-11 and layoff shortly there after.
The IRIS motors did a good job disipating heat and had the insualtion to help with corona effects from the drives. I really only saw a couple of those, they were introduced before I started to work for them so most the testing was done. TEFC motors may draw alot of current up at the high end due to the fan, as its dynamic the more you spin it the more it draws, thats the only other reason it may not be recomended above 75Hz that I can think of, if you can keep your carrier lower, although it makes more noise it tends to run cooler, although not always! If you have a way to measure if the houseing reaches 150'F (65'C)then you are getting to warm esp for run of several hours. The maxium internal temp should not go above 150'c on the coils.
chris