PAM Motor Basics 1

[roryrobb]

Can anyone explain the basic theory behind pole amplitude modulation in an electric motor. I have a 6500 hp with 9 leads connected 2 par star on high speed (894) and series delta on low speed (710). Motor has 120 slots/coils. I can see no change in poles when reconnecting from 2 wye to 1 delta, and it looks like 6 poles in either. What am I missing? Leads 1,2,3,7.8.9 have one coil end while 4,5,6 have two.

 

[acmotorengineer]

This is a technique used in the design of three-phase induction motor stator windings. Using p.a.m. the motor can be arranged to have two or more different operating speeds with only a single stator winding. Unlike the pole-change winding, speed ratios other than 2:1 can be obtained. Basically, selected halves of the phase windings are reversed; special groupings of the coil are used and in some cases certain coils are omitted. The switching is done by control circuitry external to the motor. Many different configurations are possible, depending on the particular application.

 

[jbartos]

Suggestion: Visit

http://www.ckit.co.za/Conveyor/Troughed/Electric_Motors/Alstom/Alstom - SpeedControl.htm

etc. for more info.