Torque from 280KW Motor & VSD
Torque from 280KW Motor & VSD
(OP)
Is there any other way to prove the torque being produced at a motor shaft is correct, apart from using tha torque / current diagnostic on a VSD HMI?
I have a situation where the customer has replaced a old DC system with a closed loop VSD / Motor. The drive has autotuned offload correctly. However when running the machine it runs at approx 100% torque and @ FLC.
Obviously on a DC system a quick check of IA and VA will give you some indication however is somewhat more difficult on AC.
I have a situation where the customer has replaced a old DC system with a closed loop VSD / Motor. The drive has autotuned offload correctly. However when running the machine it runs at approx 100% torque and @ FLC.
Obviously on a DC system a quick check of IA and VA will give you some indication however is somewhat more difficult on AC.





RE: Torque from 280KW Motor & VSD
A normal motor is symmetric so you need only measure one phase. The problem usually is that phase current and phase-phase voltage is available. So you probably have to measure with a two (or three) wattmeter system.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Torque from 280KW Motor & VSD
respectfully
RE: Torque from 280KW Motor & VSD
Since there is an essentially linear relationship between slip and torque, a simple strobe light on the shaft and a calculation of % slip should give you torque.
For example, in the 50Hz world, a four pole motor has a sync speed of 1500rpm. Let's say the motor is nameplated 1460rpm.
At no-load the motor will turn very close to 1500rpm. At 100% rated load, the shaft speed will be 1460rpm. At 25% load the speed is 1490, at half load it is 1480, at 75% it is 1470, and at 50% overload it is about 1440.