GB191018191A - Improvements in or relating to Electric Motor Controllers. - Google Patents

Abstract

18,191. Adams Manufacturing Co., [Cutler Hammer Manufacturing Co.]. July 30. Electric braking.-In an electric motor control system arranged for electrical braking, the series field is separately excited by connexions which are automatically interrupted when the armature commences to generate current. The armature circuit includes a main switch 1, resistances R<1>, R<2>, R<3> controlled bv switches 3, 4, 5 respectively, and the series field S. The braking-circuit is controlled by a switch 11, and includes the winding 13 of a relay-switch 14. An auxiliary circuit for separately exciting the field S when the motor is required to act as a brake is controlled by a switch 9 and includes a resistance R<4>. The switch 14 controls the switch 9 to allow the latter to open when the armature is generating sufficient braking- current to excite the field S. All the electromagnetic switches and a mechanical brake 15 are governed by a master controller M, the switches 1, 3, 4, 5 being operative in its running positions. In the first braking position, the switches 3, 4, 5 and 11 are closed by means of the controller M, and a circuit including the switch 14 and the winding 10 of the switch 9 is also made. Should the armature A not at once generate current, the relay - switch 14 remains in its closed position, and the switch 9 consequently supplies an independent exciting- current, limited by the resistance R<4>, to the field S. A braking-current is then generated, and, exciting the coil 13, causes the opening of the switches 14, 9, the excitation being maintained by the braking - current. In the remaining braking positions of the controller M, the resistances R<2>, R<2>, R<1> are inserted into the braking-circuit.