Patent GB-376448-A (GB)
Title: Improvements in and relating to starting devices for electricallydriven machines
IPC: H02P1/56
Filed: 1931-06-05
Abstract: 376,448. Master control of several motors. INTERNATIONAL GENERAL ELECTRIC CO., Inc., 120, Broadway, New York, U.S.A.-(Assignees of Allgemeine Elektricitõts Ges.; 2, Friedrich Karl-Ufer, Berlin.) June 5, 1931, No. 16484. Convention date, June 5, 1930. [Class 38 (iii).] Individual motors X of a paper-making machine are started one at a time by a common automatic contactor starter IV and are then transferred to a Ward-Leonard supply P1, N1, thereafter being automatically maintained at the desired speed by electric differential field regulators XII, XIII. The accelerating relay II is connected in shunt to a resistance VII in series with the motor being started, this resistance being so chosen that the operation of the relay II suits the power of the motor being started. If there are several motors of equal power a common resistance VII<1> is used. A starting operation is initiated by momentary closure of a button V causing starting relay VI to connect the motor to the starting bus-bar R6, which is connected to the supply P1 through the starter IV, to maintain itself over back-contacts of running-relay VIII and stop-button IX, and to energize a control relay I. Relay I then opens contact 2 in series with all the startbuttons and closes contact 3 to apply partial energization through resistances D to the coils of contactors S, this energization being only sufficient to maintain the contactors when closed. Accelerating relay II will have opened due to rush of current through resistance VII. When this has subsided, relay II closes its contacts, thus shorting resistance D of the first contactor S, which thereupon out out a section of the starting resistance IV, and connects the resistance D of the next contactor to the contacts of relay II, so that upon the next reclosure of the contacts, a further section of resistance IV is cut out. This action proceeds until the last contactor S closes, and at its auxiliary contacts 17 completes a circuit for the running- relay VIII. This relay connects the motor directly to the supply P1, closes the circuit the electrical differential device XII, completes a maintaining circuit for itself over stop button IX and opens the maintaining circuit of starting- relay VI, which in opening de-energizes the control relay I so that all the contactors S are opened and all the start buttons are again rendered operative. To ensure correct operation of the contactors S, an auxiliary relay III is energized and opens its contact 13 when relay II closes its contacts, thus only an impulse is passed on to the contactor coils, so that, even if relay II is slow to reopen its contacts, only one contactor is closed at a time. As a small power motor might be running at full speed after a few sections of resistance IV have been cut out and consequently relay II would maintain its contacts closed, the relay III is made self-de-energizing at contacts 14, and closes with a time-lag so as to ensure closure of the remaining contactors. The contacts of the relay II can be shorted by a button XV in the event of a motor failing to start with full resistance in circuit. The whole plant can be stopped by opening switch XIV.