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Dave,
I'm sorry for the confusion -- I totally missed the fact that you are
using a 3 phase motor on a VFD. Most VFDs rectify the line AC to DC,
and then chop it back up to AC at a variable frequency to drive the
motor. I'm not familiar with VFDs that have an AC output frequency
locked to the line, but that would kinda defeat the purpose of a
variable speed drive in the first place.
You can't file flats on a three phase motor. That trick only works for
single phase motors.
I believe that with judicious choice of a run capacitor, a three phase
motor can be run on single phase power as a capacitor run motor.
Whether this arrangement would be synchronous, I don't know for sure,
but it would not be too hard to test out.
Fortunately, others have offered better suggestions than mine.
(Another) Dave
On 9/17/2014 9:37 PM, Dave Boyle wrote:
The motor is a 3 phase 208v 1/2 horse driven by a vfd. Does it make
sense to grind flats on it's armature?
On 09/17/2014 08:50 PM, David Speck wrote:
Dave,
"Pretty close" is not good enough. When your gap drifts far enough
away from optimum synchronization, the NST will fail permanently.
Look at the old posts that describe how to file flats on a motor
armature to convert it to a fully synchronous motor. Then, you can
use a Freau phase adjuster to precisely set the phase angle of the
motor without having to mechanically rotate the motor body.