Patent GB-832764-A (GB)
Title: Improvements in and relating to centralised electrical remote control systems
Inventor: ROSS THOMAS WYLIE
IPC: H02J13/00
Filed: 1956-02-06
Abstract: 832,764. Induction relays; actuation of switches. METROPOLITAN-VICKERS ELECTRICAL CO. Ltd. Jan. 30, 1957 [Feb. 6, 1956], No. 3633/56. Class 38 (5). In a centralized control system in which control ripples are superimposed on power conductors to control the connection and disconnection of remote apparatus, the latter are provided with relays comprising means responsive with predetermined time delay to the reception of a signal to disconnect the apparatus and means responsive with predetermined time delay to re-connect the apparatus after a period of time following the signal, the relay comprising main load contacts, and a motor operable by the signals to drive contact opening means by movement of the motor in one direction and operable to cause reclosure of the contacts by rotation in the reverse direction at reduced speed. In one arrangement, Fig. 1, receipt of a ripple causes contacts 10 to close to energize a winding 26 of an induction relay. A shaft 6 is thereby rotated counter-clockwise so that an arm 13 hits a contact arm 15 to open load contacts 16, 17 with a snap action, and also if the ripple lasts long enough contacts 20, 21 to de-energize a winding 27 on the relay. When the ripple ceases, the arm 13 rotates back at a reduced speed and after, say, 30 minutes, the arm 14 hits contact arm 18 and recloses contacts 20, 21 to re-energize winding 27. This causes the shaft 6 to speed up and when lost-motion at 28 is taken up, contacts 16, 17 are reclosed with a snap action. The arms 13, 14 are independently adjustable to preset the two delay periods. In a second form, Fig. 2, the winding 26 is energized on receipt of a ripple to cause the disc 45 to rotate counter-clockwise. When the ripple ceases, a winding 31, which is energized by closure of contacts 52, 53 at the start of the movement, causes the disc to return. If the ripple stops when a pin 46 is opposite a recess 43 in an arm 41, the pin enters the recess at the start of the return movement and raises the arm 41 to open load contacts 16, 17 and contacts 20, 21 which normally short circuit a resistance 37 in series with winding 31. The resistance is thus put into circuit and the return of the disc is slowed down, the contacts being latched open by the arm 15a engaging a step 50 on a latch 47. Eventually, a pin 51 on the disc trips the latch and the contacts reclose, and then a pin 54 opens contacts 52, 53 to de-energize winding 31. The pin 46 is carried by an adjustable arm 55. If the ripple is too short, the pin 46 does not reach recess 43, and if too long it rides past the arm 41 on the return of the disc and does not enter recess 43. In either case, the contacts 16 and 17, 20 and 21 remain closed. A further signal may be sent during the return movement of the disc to send pin 46 back to recess 43 to prolong the return movement. The extending signal may be so controlled that the timing of the signal is determined automatically in accordance with the load, Fig. 3 (not shown). Specifications 419,917 and 517,971 are referred to.