GB640503A - An improved electric regulator - Google Patents

Abstract

640,503. Automatic temperature control systems; inductances. LANDIS & GYR SOC. ANON. May 22, 1946, No. 15505. Convention date, May 28, 1945. [Classes 38 (ii) and 38 (iv)] An electric regulator, Fig. 1, for correcting changes in a physical quantity, e.g. temperature, comprises an element 4 sensitive to changes in the quantity, an inductive unit 1-3 variable by the element 4 and a second similar unit 5-8 which is present in accordance with the quantity to be controlled and is also responsive to an anti-hunting control. A change in the magnitude of the quantity to be controlled varies the air-gap of the unit 1-3, the coils 1, 2 of which are connected in series with the coils 5, 6 of the unit 5-8, so as to unbalance the normally balanced watt-meter relay 9-13, and cause a disc 12 to operate contacts 17 and energize one or other of relay coils 19 or 20. Assuming the coil 19 is energized, closure of the relay contacts causes (a) energization of a holding circuit for the coil 19 over contacts 221, (b) energization of heating windings 16a on the unit 5-8 to form a thermal feed-back device for preventing hunting; (c) connection of a regulating device 18 to the supply a, b; (d) insertion of a resistance 23 for damping the watt-meter to prevent hunting thereof; and (e) energization of a motor 22, adapted after a predetermined time delay to actuate contacts 223 to stop the regulator 18, contacts 222 to de-energize the heater windings of the element 16a, and changeover contacts 221 to de-energize the coil 19 and prepare the holding circuit of the coil 20. As shown in Fig. 3, the feed-back device on the unit 5-8 comprises two fixed cores 37, 38 mounted on rods 42, 43 and an armature 39 which may be adjusted by a knob 30 or by the action of the feed-back device. The latter comprises two brass tubes 27, 28 mounted at one end on a fixed plate 26 and carrying a plate 29, supporting the knob 30, at the other end. The end of the knob bears on a plate 32 attached .to two brass tubes 33, 34 joined by a plate 35 which carries, on a rod 36, the armature 39. The brass tubes 27, 28 ami 33, 34 have heating windings which are respectively energized by the closure of the contacts of relays 20, 19. Expansion upon heating causes the armature to be moved to introduce a control which compensates for over-regulation, after a deviation in the quantity to be controlled has occurred. In a second embodiment (Fig. 2, not shown), on-off regulation is obtained by dispensing with one of the relay coils 19, 20, and employing in the feed-back device only one pair of heater tubes. Instead of using inductive units 1-3, 5-8, variable condensers may be employed. Speci. fications 609,484 and 633,753 are referred to.