Device for monitoring state of multistranded fuse in grid network - has constant current source connected to fuse and potential difference across fuse is measured to determine resistance

摘要

The device includes a clock circuit (10) which produces a train of pulses during the test to guide the central current generator (11). The potential difference is measured (2) by a multichannel sampling circuit (23) incorporating an analogue the digital converter which receives the output from a variable gain amplifier (22) whose input is switched between the potential difference, Ue, and a reference voltage (20), Uo. The mean potential difference of the channels is calculated (3) and the state of the fuse is determined by comparison of its actual resistance with that of an undamaged fuse. A sixteen character alpha numeric display (31) shows "fuse correct", "fuse damaged", or "fuse inoperative". USE/ADVANTAGE - Step-down medium or low voltage transformer in national grid allowing anticipation of expensive failure.