GB190604514A - Improvements in Systems of Electric Motor Control. - Google Patents

Abstract

4514. British Thomson-Houston Co., [General Electric Co.]. Feb. 23. Switches.-Relates to means for starting or stopping an electric motor, such as for printing-presses, from any one of several stations, without altering the position of the main controller after it has been moved to a running position. The motor M, having series and shunt field windings b, c, is connected to the line through a controller K, and may be started from any one of the stations 1, 2, 3, 4. The switch lever 8 is normally held in the position shown by means of the spring 11 ; when it is moved to make contact with either of the contacts 9, current passes from the line L, through the switch S, the relay O, switch arm 8, contact 9, lead 6, controller contacts k, k<1>, k<2>, k<3>, and the other side of the switch S to the line L'. This energizes the relay O, and maintains it as long as the contacts k, k<1> are in engagement, preferably during the low-speed positions of the controller. The relay O connects the contacts o<1>, allowing current to flow from the line L through the switch S, contacts o', and the shunt field c to the line L<1>. Another circuit comprises the contacts o', series field b, armature a, wire 12, resistance R, controller contacts k<5>, k<4>, k<3>, k<2>, switch S, and the line L<1>. Thus the motor can be started or stopped from any one of the stations while the controller is in low-speed positions. If the arm 8 is brought into engagement with the contact 10, a circuit io shunt with the controller is established from the wire 5 to the wire 7, and thence through the resistance r and switch S, as before, back to the line. This maintains the relay, but by reason of the resistance r the current in this circuit is not sufficient to operate the relay, but only to hold it after it has been operated through the actuating-circuit: The arm is held in the portion 10 by means.of an electromagnet 13 in circuit with the push-buttons p. At any time, when it is required to stop the motor, on depression of one of the buttons p, the magnets 13 are de-energized, the spring 11 draws the lever 8 back to the position shown, the relay circuit is broken, and the contacts o<2> short-circuit the armature through the resistance shown and stop the motor.