A control device

摘要

1,067,859. Automatic temperature control. COMPAGNIE GENERALE D'ELECTRICITE. Aug. 5, 1964 [Aug. 6, 1963], No. 31772/64. Heading G3R. In an electrical system for automatically correcting deviations of a variable, the correction signal is applied through a transformer having a core of rectangular hysteresis loop material and a symmetrical semi-conductor switching device in a circuit supplied with alternating current. In Fig. 2, a heater 13 is supplied from an A. C. source S through a symmetrical semi-conductor device 3 having four junctions between layers of opposite conduction type. Variations in temperature due to heater 13 are detected by a device 45 including a thermocouple which controls the energization of a D. C. biasing winding 44 of a transformer 40 having a core of rectangular hysteresis loop material. Normally the transformer primary winding 43, which is energized from a signal generator 21 synchronized with A. C. source S, influences a secondary winding 42 so that the semi-conductor is rendered conductive by the voltage pulses of appropriate polarity applied between control electrode C and rectifiers R1 R2, but, if the temperature rises above a predetermined value, the bias of winding 44 prevents this, so that the supply to the heater is interrupted until the temperature falls. An additional biasing winding on the transformer may be energized in dependence on the temperature of the semi-conductor to safeguard the latter.