Underpowered VFD....will it work?
Underpowered VFD....will it work?
(OP)
I have a 100HP/460V synchronous motor sitting in the back of my shop along with a 40HP/460V VFD. I am hoping to hook the two parts together. The motor will be very lightly loaded with a gear box. The only thing I am concerned about is actually starting from 0RPM (kind of like a locked rotor situation). Am I going to be able to start this motor or will I need a pull-start (just kidding of course)?





RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?
Most VFDs are rated for a temporary starting overload of 200% of rated. This is for start-up since it resembles a locked-rotor condition. I am not worried about anything but the start-up.
I will most definitely work with your suggestion "electricpete", but I am still unsure as to whether I will be able to get that rotor moving.
Any other comments?
RE: Underpowered VFD....will it work?
http://208.156.24.64/index_nema.cfm/1427/0DDF742A-8790-4A21-88D139CFC069648B/
- read in particular the comment on locked rotor current in section 4.2.2 (actually referring to design A motors but applicable here I think). With VFD operation the motor is always operating on the final slope of the conventional 60HZ DOL torque-speed curve, regardless of actual motor speed. So the DOL starting current doesn't apply.
RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?
No reason why you can't run your 100 hp Sync motor on a 40 hp VFD.the VFD will give you the soft start you need.
As you mention, it will be lightly loaded, and the VFD current limits will let you know when you have exceeded it.
You say that the Sync will be driving a gearbox,but you don't mention what is the gearbosx doing.
Don't forget that you can start the Sync,but the Sync will be using nearly 40 hp just iddling.
It will have to be a very light load indeed.
Good luck
GusD
RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?
RE: Underpowered VFD....will it work?