Four terminal fail safe resistor - has conductive tracks which open circuit when subjected to abnormal thermal or mechanical loading

摘要

Each pair of two pairs of terminals is connected together by a conducting strip of a metallic material deposited on a fragile support block. The strips are shaped in an interwoven pattern, with an intervening space, such that the support block will not break along the space pattern. The strips are connected by a resistance material deposited along the space pattern and overlapping the adjoining strips. The four terminals are connected into a circuit so that the resistance material forms part of a resistor network which if interrupted causes that circuit to assume a safe condition. Any rupture of the resistance material and/or the support block due to thermal differences or mechanical force interrupts the continuity of one or both connector strips to create a safe failure condition.