field-discharge switch

field-discharge switch

[′fēld ¦dis‚chärj ‚swich] (electricity) A special type of switch that is connected in series with the field winding of an electrical machine, and that is operated to connect a resistor in parallel with the field winding before the main supply contacts are opened, in order to prevent the self-induced electromotive force in the field winding from reaching dangerous levels.