The switching circuit is coupled to the voltage supply for energizing the primary winding only to achieve a high speed, energizing only the secondary winding to achieve a medium speed, and energizing both the primary winding and {HEAD ~ the secondary winding} in {TAIL ~ series} with each other to achieve a low speed 
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The switching circuit is coupled to the voltage supply for energizing the primary winding only to achieve a high speed , energizing only the secondary winding to achieve a medium speed , and energizing both the primary winding and { HEAD ~ the secondary winding } in { TAIL ~ series } with each other to achieve a low speed
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