Measurement sensor with control loop - enabling detection of interruption of cable from remote position to prevent tampering

摘要

A measurement device sensing, e.g. pressure or temp. and converting them into electrical signals, has a multiple wire cable leading to the sensors contained in a plastics housing. Two of the wires are part of a monitoring circuit enabling detection of interruption of the cable from a remote monitoring point. The wires of the monitoring circuit cable have reduced cross-section regions and are connected to a part of the monitoring circuit mounted in the base of the housing and connected to the housing lid by a stop spring. The housing lid has a weak point or design fracture point at the location of the monitoring circuit wire cross-sectional reductions. Unauthorised opening of the housing causes the wires to break and be detected by the remote monitoring unit.