jdbrandt
Lifetime Supporting Member
I have a (*) PowerFlex 525 being supplied with 400VAC, 60 cycle, 3-phase. This is not a type-o, this is accurate.
Now, the drive clearly states that this is acceptable, since it has a wide range of input power. So, that’s good.
And, when I go online to the drive, sure enough, the DC Bus is ~545VDC, versus the traditional ~650VDC. Again, expected and good.
However (there’s always a however)….
This drive is connected to a motor with a nameplate that gives both 400V / 50 cycle and 460V/60 cycle nameplate values. (An SEW gearmotor).
The OEM decided to enter in the nameplate values for a 460V motor, and the drive does run.
Also in play here is the fact that that the OEM somehow thought to underspeed the gearboxes, meaning that in normal running, the drive is commanded to speeds in the 70HZ to 90HZ range. This is a mystery to me..because of the economy of scale, perhaps this is more closely engineered than it first appears. (I cannot verify this, unfortunately)
So, it seems to me, a few things:
#1: We need to de-rate the possible horsepower that the drive can actually deliver. Obviously, this is working, since the system is working and the loads are being driven with no apparent degradation in performance. See above, for all I know, the OEM took all this into account in the design phase.
My question is: Even though the motor has two ratings: 400VAC/50HZ/1450RPM and 460VAC/60HZ/1762RPM, which rating is the correct one for the NP values in the drive?
I ask because it seems better to hold the voltage at 400 when moving past base speed..but I might be wrong, as I am more and more these days.
Now, the drive clearly states that this is acceptable, since it has a wide range of input power. So, that’s good.
And, when I go online to the drive, sure enough, the DC Bus is ~545VDC, versus the traditional ~650VDC. Again, expected and good.
However (there’s always a however)….
This drive is connected to a motor with a nameplate that gives both 400V / 50 cycle and 460V/60 cycle nameplate values. (An SEW gearmotor).
The OEM decided to enter in the nameplate values for a 460V motor, and the drive does run.
Also in play here is the fact that that the OEM somehow thought to underspeed the gearboxes, meaning that in normal running, the drive is commanded to speeds in the 70HZ to 90HZ range. This is a mystery to me..because of the economy of scale, perhaps this is more closely engineered than it first appears. (I cannot verify this, unfortunately)
So, it seems to me, a few things:
#1: We need to de-rate the possible horsepower that the drive can actually deliver. Obviously, this is working, since the system is working and the loads are being driven with no apparent degradation in performance. See above, for all I know, the OEM took all this into account in the design phase.
My question is: Even though the motor has two ratings: 400VAC/50HZ/1450RPM and 460VAC/60HZ/1762RPM, which rating is the correct one for the NP values in the drive?
I ask because it seems better to hold the voltage at 400 when moving past base speed..but I might be wrong, as I am more and more these days.