| 摘要 |
1,119,370. Rolling. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. 25 Aug., 1965 [15 Sept., 1964], No. 37639/64. Heading B3M. [Also in Division H2] In a rolling mill drive comprising a synchronous motor 1 whose field excitation is supplied by an exciter machine 4, the motor size is reduced by supplying the exciter machine field winding 5 through at least one resistor section R1 or R2 shunted by a contactor A or B controlled automatically in dependence upon the position of the front end of a workpiece threaded into the mill. As shown, there are two individually adjustable sections and contactors controlled by respective relays RA, RB operable by a limit switch or a photoelectric device or a detector sensing the magnitude of the motor current. Timing devices may be provided to delay contactor operation until the motor field has built up adequately and to drop out one of the relays to ensure a specific amount of excitation at a specific instant of the duty cycle. There may be any number of resistor sections, and a field rheostat RF determines the field circuit resistance at no-load. The exciter machine may be of either conventional or brushless type having a shunt or separately excited field winding 5 supplied from a generator through a rotating rectifier. |
