Sentence:  At the conclusion of each wind, the movement of the driver's control lever back to the neutral position, and consequently the movement of the Ward Leonard controller back to its neutral position, firstly opens the directional contacts which isolate the generator field from the Ward Leonard exciter and, secondly, operates contactors which eliminate the effect of the residual field by <WSD>suiciding</WSD> the generator field as outlined above. 
Meaning of the word marked with <WSD> tags:  To self-destruct.