| 摘要 |
882,940. Thermal switches. TEXAS INSTRUMENTS Inc. April 13, 1960 [April 15, 1959], No. 13275/60. Class 38 (5). A thermal switch comprises an insulating cup-shaped casing 1 carrying fixed contacts 3, 5 co-operable with movable contacts 21, 23 mounted on a bimetal plate 15 loosely carried by an adjustable post 11 and having ears 16 co-operable with projections 27 to prevent plate rotation. A heater 35 comprises a loop 47 engaging an insulating cover 29, and legs 39 having lugs 41 sprung into grooves 45 in the casing 1, one heater terminal 43 being connected to contact terminal 7 which, with its fellow terminal 9 and heater terminal 44 is sealed to the casing 1 by a potting compound 57. The loop 47 of the heater may be replaced by a straight ribbon-like portion, by a rectangular portion having an aperture adjacent the post 11 or by a multi-looped wire, with wire legs and terminals, fitted in a groove in the cover 29, Figs. 6, 7, 8 and 9 (not shown), all the heaters operating at a non-incandescent temperature. The switch may be used to protect the windings of a split-phase electric motor against overload and stalled-rotor conditions, Figs. 10 and 11 (not shown), the switch and heater design being such that the plate 15 and the motor windings heat and cool at approximately the same rate to prevent the windings exceeding a critical temperature during the initial period of the overload, Fig. 13 (not shown).
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