GB583186A - An electrically controlled temperature regulator - Google Patents

Abstract

583,186. Automatic control systems. LANDIS & GYR SOC. ANON. March 16, 1944, No. 4948. Convention date, May 17, 1943. [Class 38 (iv)] Temperature.-A temperature regulator having a thermal amplifier incorporated therein comprises a feeler resistance 1 (Fig. 2) connected in series with one coil 2 of an operating instrument (e.g. a Ferraris contact wattmeter or differential relay), a second temperaturedependent resistance 3 (e.g. a metal filament lamp) being connected in parallel with the coil 2. Any change in the resistance of 1 causes an alteration in the current distribution through 2 and 3, thereby producing an amplification across 2 of the current change through 1. The resistance 3 may have a positive or negative temperature coefficient, being connected in series with the coil 2 in the latter case. The effect of ambient temperature changes on the thermal amplifier may be nullified in the case of a Ferraris contact wattmeter by providing a second amplifier 31 (Fig. 4) in the circuit of the second coil 21 of the wattmeter and acting in opposition to the amplifier 3. Fig. 4 also incorporates a resetting device comprising heaters 4, 41 acting on the amplifiers 3, 31 respectively when switched in by contactor 6 worked by the operating instrument to effect a temporary displacement of the standard value to which the device has been set by the variable resistance 5. The sensitivity of the operating instrument may be increased by providing the moving element with a spring, and alternately switching in the resetting heating devices by means of a time switch 10 (Fig. 7), thus maintaining the instrument in periodic oscillation and avoiding starting friction. The system may be applied to the shifting of a regulated temperature in accordance with a second temperature, the variable resistance 5 being replaced by a second feeler resistance. According to the Specification as open to inspection under Sect. 91, the system may be applied to the remote indication of temperature by using an ordinary wattmeter with a temperature scale as the operating instrument. This subject-matter does not appear in the Specification as accepted.