View Single Post
Old 12th Feb 2018, 5:27 pm   #15
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
Default Re: Single phase ex-avionics motor start up?!

It's a split-phase motor, in which one winding is fed 90° out-of-phase; but that phase shift is created using a local capacitor, which is part of the motor's control gear. So the complete system consisting of the motor and all its control gear does only require a single phase from the mains supply.

If the capacitor is only used during starting (both to force the motor to start in the right direction and to provide the extra torque needed to accelerate from rest), there will be some sort of switching mechanism to disconnect it once the motor is up to speed. This may be a centrifugal switch, a fancier arrangement with some sort of speed sensor operating a relay contact, or just a simple timer.
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments.
julie_m is offline