GB235702A - Improvements in the automatic control of groups of dynamo electric machines - Google Patents

Abstract

235,702. English Electric Co., Ltd., and Bolton, R. A. R. May 26, 1924. Systems depending on the use of two or more machines.-A dynamo-electric machine in a condition for operating is automatically selected for starting from a group which may include machines not in such a condition. A moving contact travels over a series of contacts 2 - - 5 each of which is connected to an automatic starting means. Associated with each machine is a circuit including one o: a series of solenoids 11 - - 14 controlling stops 6 - - 9 in the path of the member 1 carrying the moving contact. The stop corresponding to a machine is thus placed in the path of the member, under manual or automatic control, when the machine is in condition for service; such control may include a switch on an automatic starter for the machine, a centrifugal switch, or a relay energized by the load current of the machine. The contacts 2 - - 5 may be in a straight line, an arc, or a circle and the moving member may be actuated by a solenoid or a torque motor and through a rack, a ratchet, or a direct coupling; the biassing spring 21 may be omitted. The automatic starting-gears include retarding-devices which prevent starting until the moving member has rested for a period upon any contact. In the example given the selecting device is under the control of a switch 27 controlled by conditions demanding an increase in the number of machines in service. Low voltage in the line, for example, may cause a solenoid 28 to permit closure of this switch, whereupon solenoid 22 is energized and the switch member 1 moved from its rest position 20 over contacts 2, 3-the machines controlled .thereby being in service or out of commission and their stops 6, 7 being therefore retracted-and held over the contact 4 by the stop 8 till the corresponding machine has started up and the line conditions have caused switch 27 to open. The member 1 then returns to its rest position and the stop 8 is retracted. The stops 6 - - 9 may themselvesserve as the switch contacts.