Browse Prior Art Database

Temperature Detector

IP.com Disclosure Number: IPCOM000097865D
Original Publication Date: 1961-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Meyers, AJ: AUTHOR

Abstract

Certain types of thyratron transistors exhibit an open base breakdown voltage characteristic BV. This characteristic is temperature sensitive, i. e., the device can be switched from a low current operating point A to a high current operating point B with a small change in ambient temperature.

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Temperature Detector

Certain types of thyratron transistors exhibit an open base breakdown voltage characteristic BV. This characteristic is temperature sensitive, i. e., the device can be switched from a low current operating point A to a high current operating point B with a small change in ambient temperature.

In the range of 30 degrees to 60 degrees C. the device responds to temperature changes as low as .2 degrees C. for low voltage loads and approximately 2 degrees to 5 degrees C. for high voltage loads. By properly calibrating the breakdown voltage characteristic with temperatures within the above range, the device is employed in a circuit for controlling the flow of current to a protective device.

Thyratron transistor T is connected in series with resistor R1 and a relay coil, between +V and ground. The value of R1 is selected by determining the operating current required to activate the relay coil and the breakdown voltage for the required temperature. When so employed, this circuit handles currents in excess of 250 ma. enabling the largest circuit breakers to be operated directly. Presently available arrangements require the use of an intermediate device to provide the operating current for the circuit breaker. The arrangement has the additional advantage of assuring fast and positive action. This is because the rise in current flow from the microampere range to 200 ma. occurs in a few microseconds, making the circuit operation depend on the operating t...