Scanning device for the graduation scale of a position measurement system for use in an explosive environment has simple sensor protection circuit comprising thermal fuses contained with the electronics module protective housing

摘要

Device comprises a sensor that can be brought into working contact with the scale and which is supplied via electrical connectors and coupled to an electronic module. The connectors (10) to the sensor (2) have fuses (11) that are contained within a protective housing (30) of the electronic module (3). The electronic analysis and control module is housed in a protective housing preventing any charge disturbances or sparking from causing ignition. The sensor itself must by necessity be within the hostile environment. The fuses are rated so that an excessive current cannot be supplied to the sensor, preventing any untoward happenings.