Hi all,
I have a duplex compressor with two 5hp 3phase motors on it. The compressor can support both continuous run (head unloaders) or start/stop operation. I have single phase input.
Is there any advantage or disadvantage to running both motors from a single properly sized VFD (20HP) versus having a smaller VFD (10HP) for each motor? Under the single-VFD they would always be started and stopped at the same time.
The only downside with a single VFD that I have come up with is the requirement to have overload protection on each motor for a single VFD, versus leveraging the built-in protection from the individual units. I think this requirement offsets the slight premium one pays when buying two units.
Regarding continuous run - when using a VFD is this feature necessary and/or desirable when frequent cycling would occur? The conventional wisdom is that you should have fewer than 5 or 6 motor starts per hour - does this apply to a VFD which is ramping up slowly?
Additionally, if using the unloaders on a single VFD, the load on one pump would load or unload before the other, would this cause any issues?
Thanks,
Don
I have a duplex compressor with two 5hp 3phase motors on it. The compressor can support both continuous run (head unloaders) or start/stop operation. I have single phase input.
Is there any advantage or disadvantage to running both motors from a single properly sized VFD (20HP) versus having a smaller VFD (10HP) for each motor? Under the single-VFD they would always be started and stopped at the same time.
The only downside with a single VFD that I have come up with is the requirement to have overload protection on each motor for a single VFD, versus leveraging the built-in protection from the individual units. I think this requirement offsets the slight premium one pays when buying two units.
Regarding continuous run - when using a VFD is this feature necessary and/or desirable when frequent cycling would occur? The conventional wisdom is that you should have fewer than 5 or 6 motor starts per hour - does this apply to a VFD which is ramping up slowly?
Additionally, if using the unloaders on a single VFD, the load on one pump would load or unload before the other, would this cause any issues?
Thanks,
Don