Limit-value detector for detecting leakage currents at high-voltage insulators which are under voltage or of stray currents in surfaces of metal bodies

摘要

To detect the conductivity of the contamination layer of a high-voltage insulator (1) under voltage or stray currents in metal bodies (17), for example in a pipeline run parallel to a high-voltage line, a measurement value pick-up is used which consists of two electrodes (3, 4 and 15, 16, respectively) attached at a predetermined distance to the surface of the high-voltage insulator (1) or of the metal body (17), respectively, which are connected to light-emitting diodes (7, 8). The light-emitting diodes (7, 8) are associated with the end (9a) of an optical waveguide (9) which is extended to a receiving device (11). The other end (9b) of the optical waveguide (9) is associated with a photodiode (12) which feeds a display or recording device (14) via an amplifier (13). At a particular level of the leakage current occurring at the insulator (1) or at the metal body (17), the light-emitting diode (7 or 8) transmits a light signal which is transmitted via the optical waveguide (9) to the receiving device (11) where it is recorded. <IMAGE>