We have 3 identical inverters each lowering a load.
When we raise the speed, two of the loads are unstable. They jitter going down. There is an oscilation as if we where rapidly changing the speeds. Those two loads are the heaviest ones.
The drives are equiped with external braking resistors and without these we would get DC Buss Over Voltage failures.
Raising the lowering speed increases this effect even more.
Raising the loads, the drive have ample power. Max Amps is 6 but they use only 4.5 at 60HZ rising. Lowering, they cannot do it with stability above 15 HZ.
Any suggestions?
They are running at fix speed with accel and decels of 2 seconds.
Say we lower the loads at 20Hz, they jump all over, then we reduce while running, at 15Hz... they become stable again.
When we raise the speed, two of the loads are unstable. They jitter going down. There is an oscilation as if we where rapidly changing the speeds. Those two loads are the heaviest ones.
The drives are equiped with external braking resistors and without these we would get DC Buss Over Voltage failures.
Raising the lowering speed increases this effect even more.
Raising the loads, the drive have ample power. Max Amps is 6 but they use only 4.5 at 60HZ rising. Lowering, they cannot do it with stability above 15 HZ.
Any suggestions?
They are running at fix speed with accel and decels of 2 seconds.
Say we lower the loads at 20Hz, they jump all over, then we reduce while running, at 15Hz... they become stable again.