Patent GB-614631-A (GB)
Title: Improvements in automatic electric regulating systems
IPC: H02J3/14
Filed: 1945-07-03
Abstract: 614,631. Automatic control systems. GRAY, A. H., BROWN, G. L., and METROPOLITANVICKERS ELECTRICAL CO., Ltd. July 3, 1945, No. 16920. [Class 38 (iv)] [Also in Groups XXXVI and XXXVII] In an arrangement for limiting the maximum demand on a source of supply either by switching off the load or by controlling the speed of an auxiliary source, the control action only takes place after a portion of a demand period has elapsed. This portion may be predetermined or may depend on the load. In the system described in detail, the control takes place on the governor of an auxiliary generator and acts to keep the load on the main supply source constant. Circuit arrangements. As shown, a time switch TS periodically closes contact 43 for an instant to start a demand period and the consequent momentary operation of clutchreleasing magnets OC4, OC14 allows shafts 7, 10, driven respectively by a kilowatt or kilbvar hour meter 1 and by constant-speed device 11, to return to their normal positions. For an initial period, no control is exercised. The period of control is initiated by the closing of contacts A, A<SP>1</SP>, Fig. 2. These may be contacts of a relay OCA which operates and locks up in response to the closure of contacts 35, 36 (or 35a, 36a) actuated by device 11, Fig. 1, when the inactive period is to have a predetermined duration. Alternatively, OCA may be omitted and the contacts A, A<SP>1</SP> may be the contacts 8, 9 carried respectively by the shafts 7, 10. The period then begins at a point that depends on the load. With contacts A, A<SP>1</SP> closed, the source of supply is connected to a change-over switch 23 which is constantly driven by the meter mechanism 1 and connects alternately the operating coils RC, LC of a pair of contactors. A similar switch 30 is driven by the mechanism 11 which also drives an interrupter 33. The arrangement is such that when the load has the desired value the change-over switches operate at the same speed and since, initially, they connect up different contactors, no controlling effect is produced. Whenever the speeds differ, however, a circuit is made for one or -other of the contactors and this opens a short-circuit on the armature 44 of a servomotor for effecting the desired correction. When consumption is low, RC operates and in addition to controlling the servomotor, disengages a clutch 27 to stop switch 30 and interrupter 33. When consumption is high, LC operates and stops switch 23. Consequently, after the lapse of a period of time, or the consumption of a certain quantity of electricity, one switch changes over without the other and the contactor is released. The correcting action is repeated if necessary until the switches are operating at the same speed. At the end of a demand period, OCA, if provided, is unlocked and a new demand period is begun by the momentary operation of contact 43. Alternatively, addition contacts may be included between 8 and 9 or 35, 36, which cause the load to be raised to a predetermined value at the commencement of each maximum demand period; the load apparatus itself may be controlled directly; and either of the shafts 7, 10 may operate warning devices. Specification 418,782 is referred to.