GB321300A - Improvements in or relating to electrical control systems - Google Patents

Abstract

321,300. Johnson, E. M., and Associated Electrical Industries, Ltd. Oct. 13, 1928. Systems depending on the use of two or more motors; controlling motors by varying terminal voltage.-In a system of control for two motors 15, 19 fed by variably excited generators 11, through switches 13, 17 for connecting separate motors to separate generators or both motors to either generator at will, means are provided for ensuring that both the motor field-windings 5, 7 are excited when both motors are receiving current from the same generator. This is effected by taking the circuit energizing the fieldwinding 9 or 10 of the active generator through contacts of two controllers 6, 8 which are associated respectively with the two motors 15, 19. If either controller is in its " off " position, where the corresponding motor field is dead, there is a break in the circuit of the generator field and consequently no current to the motors. The circuit passes through switches 37, 38 which may be interlocked or coupled with the switches 13, 17, as an additional safeguard. The controllers are arranged to connect the respective motor fields to line wires 23, 24 through groups of reversing contacts 25, 29; the controllers also vary resistance 34, 36 n the fields of the respective generators. When both motors are on one generator an additional current-limiting resistance is put in the generator field. In a slight modification the motors are reversed by reversing the generator fields. The single motors and generators may be replaced by groups of machines.