초록 ▼

An elongate resistive sensor useful as an element of a pneumatic manifold failure detecting and locating system. A sensing loop is based on a coaxial cable having a core of known resistance per unit length. A eutectic salt impregnated insulant separates the core and sheath but has a temperature brea

An elongate resistive sensor useful as an element of a pneumatic manifold failure detecting and locating system. A sensing loop is based on a coaxial cable having a core of known resistance per unit length. A eutectic salt impregnated insulant separates the core and sheath but has a temperature breakdown characteristic which provides the sensing function. Upon a pneumatic manifold failure, the sensing cable is heated, the eutectic salt insulator breaks down, a core-to-sheath short occurs, and currents in the sensing cable are substantially altered as a result. The cable is connected as a loop, and differential currents into the ends of the loop are detected and processed to determine the position of the short. Terminating resistors are associated with connectors which connect multiple cable sections into a single loop, and the terminating impedance is further sensed to determine an open circuit condition at any connector.

대표청구항 ▼

A sensor for determining the location of overtemperature conditions, the sensor comprising, in combination: an elongate coaxial sensor cable having a conductive metallic sheath and a conductive metallic core both made of metals capable of withstanding, without failure, the heat of the overtemperatur

A sensor for determining the location of overtemperature conditions, the sensor comprising, in combination: an elongate coaxial sensor cable having a conductive metallic sheath and a conductive metallic core both made of metals capable of withstanding, without failure, the heat of the overtemperature condition, the core being positioned within and coaxial with the sheath, the elongate cable being sufficiently flexible to be routed in proximity to a system to be monitored, a eutectic salt insulator interposed between the core and sheath for preventing contact therebetween, the eutectic salt having a melting point related to a design temperature at which the overtemperature condition is to be detected, at least one of the core or sheath having a predetermined and measurable resistance per unit length sufficiently high to allow differential drive and sensing from the respective cable ends to isolate the position of a core-to-sheath short, the eutectic salt insulator being constructed such that when heated to the design temperature at a point of overtemperature condition it provides a core-to-sheath short at said position rendering the core-to=sheath resistance determined by differential driving and sensing the cable from its respective ends an indication of the position of the short along the cable.