Electrical transmission or interconnection systems – Switching systems – Condition responsive
Patent
1997-03-21
1998-11-24
Gaffin, Jeffrey A.
Electrical transmission or interconnection systems
Switching systems
Condition responsive
307116, 374112, 374132, 219494, H01H 3700
Patent
active
058412042
ABSTRACT:
A temperature control system and method for regulating the temperature of an external device or load is provided which maintains the actual ambient temperature of the external device at a desired set point temperature. The temperature control system includes a solid state temperature sensing device for sensing the actual temperature of the external device, and generating a sensor output voltage proportional to the actual temperature. An adjustable voltage dividing circuit generates a temperature compensated set point voltage proportional to the desired temperature. A fixed voltage dividing circuit generates a reference voltage having a predetermined magnitude. A first comparator compares the set point voltage to the sensor output voltage, and generates an output signal indicating whether the sensor output voltage is maintained at the set point voltage. A second comparator detects whether the external device is maintained in an "off" or "on" state by comparing the set point voltage to the reference voltage. A solid state switching device is activated or deactivated based on the voltage levels of output voltages generated by the first and second comparators. The switching device, in turn, controls the operation of a relay. When the switching device is deactivated, the relay is maintained in a normally open position, blocking current flow therethrough to deenergize the external device. When the switching device is activated, the switching device allows current flow therethrough and the relay is maintained in a closed position. When the relay is maintained in the closed position, a power supply energizes the external device.
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National Semiconductor Corporation/Linear Databook 2/pp. 6-4 & 6-11.
Gaffin Jeffrey A.
Paladini Albert W.
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