adccommunitymod (AutomationDirect) asked a question.
Running 5hp VFD as Single Phase Input
Created Date: December 03,2014
Created By: dieseltwitch
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Im not 100% sure but i remember a reading that AD's drive will detect if they are not connected to 3 phases? I have an application where I need two pumps to run in total sync. I need to hook the two pump physical together. But only need one motor, roughly 4hp... is it posible to use a 5hp or 7Hp drive and derate it? or will it fault out?
Created Date: December 03,2014
Created by: Cow
I have a GS2 drive here at home I tinker with running on single phase. It drives a motor with no load connected without issue.
General rule of thumb when feeding a drive with single phase is a 50% derate. So you would need an 8hp drive minimum. For compressors and other hard starting applications it might even drop to 35%, but it's been awhile since I looked into it so I could be wrong.
Created Date: December 03,2014
Created by: Tinker
From previous threads it sounds like officially/theoretically, they should detect phase loss and fault, but in practice more than one person has said they have run larger drives on single phase.
Note that as that as single phase (for drives not specifically so rated) does not seem to be officially sanctioned, it is possible that a firmware change might disable the ability without warning. I don't believe field updates possible on GS drives, so that wouldn't be a problem, but just because someone ran a drive they bought months/years ago on single phase does not necessarily mean one you buy today will run on single phase (but it might)
Created Date: December 03,2014
Created by: dieseltwitch
Ok, so it sounds like it would be better if I just got a drive, and motor and tested before I went any further.
Created Date: December 03,2014
Created by: dieseltwitch
what about running two smaller motors on the same shaft? and just using a 4-20 mA signal to sync their RPM's?
Created Date: December 04,2014
Created by: mwdkmpr
We have a handful of GS3-2030 drives running on single phase. They are driving 15 HP blower motors. They all seem to be working fine.
what about running two smaller motors on the same shaft? and just using a 4-20 mA signal to sync their RPM's?
If you can think of a way to adjust the speeds to balance the amp draw of the motors this would be better. I don't know how except through a PLC.
Created Date: December 04,2014
Created by: jwbaker3
They will cost more but I know some other manufactures make 5 hp 230 single phase in 3 phase out drives. Yaskawa makes one in the V1000 series, others may also. I think keeping the motors on one drive (from any manufacturer) will be better for control than trying to control 2 drives together. There will be slip on the motors already if you add another drive that is one more thing to add variation to the speed between the two motors. We had a project that two driven devices had to run at the same speed for process control, we tried a lot of things, two drives slaved to each other, one drive with two motors, finally used a jack shaft with one motor to drive both. This project was before closed loop vector drives.
JW
Created Date: December 03,2014
Created by: dieseltwitch
Im not 100% sure but i remember a reading that AD's drive will detect if they are not connected to 3 phases? I have an application where I need two pumps to run in total sync. I need to hook the two pump physical together. But only need one motor, roughly 4hp... is it posible to use a 5hp or 7Hp drive and derate it? or will it fault out?