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Circuit Protection

IP.com Disclosure Number: IPCOM000092780D
Original Publication Date: 1967-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Griffing, BM: AUTHOR

Abstract

A resistor in a controlled heat transfer environment utilizes the transitional phenomena of a boiling liquid to provide the functions of both a resistor and a fuse. The graph illustrates the typical heat transfer characteristics of a boiling liquid around a heat source plotted against the temperature of the source. Nucleate boiling is initiated at 10. Heat transfer steadily increases with source temperature up to transition point 11. Then an increase in source temperature encounters transitional boiling as is shown by the dotted line during which the heat transfer capability actually decreases radically. As film boiling develops, the heat transfer characteristic begins to increase but does not return to level of 11 until point 12 is reached which requires a radical increase in the source temperature.

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Circuit Protection

A resistor in a controlled heat transfer environment utilizes the transitional phenomena of a boiling liquid to provide the functions of both a resistor and a fuse. The graph illustrates the typical heat transfer characteristics of a boiling liquid around a heat source plotted against the temperature of the source. Nucleate boiling is initiated at 10. Heat transfer steadily increases with source temperature up to transition point 11. Then an increase in source temperature encounters transitional boiling as is shown by the dotted line during which the heat transfer capability actually decreases radically. As film boiling develops, the heat transfer characteristic begins to increase but does not return to level of 11 until point 12 is reached which requires a radical increase in the source temperature.

By using resistors, etched by printed circuit techniques, which are immersed in a boiling liquid environment such as an inert fluorocarbon liquid in a saturated state, the resistor can act as both a resistor and a fuse. By appropriate selection of parameters, heat dissipation from the resistors into the liquid as a result of normal current now can effect boiling in the nucleate range 10-11. Current in excess of normal causes boiling to pass transition point 11 which results in a radical increase in temperature of a resistor. The latter rapidly surpasses its heat handling capability and is destroyed thus acting as a fuse.

A particular application of...