Indicator unit for displaying voltage condition of HV network - has dual signal input from independent capacitor couplings and logic evaluation of signals for self monitoring visual indication of state

摘要

The indicator unit for a medium or high tension AC switching installation has a pair of identical capacitor coupling assemblies (2,3) independently mounted on a live conductor (1) within switchgear, e.g. a busbar. The capacitors have their outer poles (5) separately connected to terminals (9,10) of a signal processor (11) via screened cables (8,7). The signal processor incorporates a logic module (16), and red/green indicators (17,18) which are illuminated depending on whether both or neither of the terminals are live. A potential on only one of the terminals deactivates both indicators to show system fault. USE/ADVANTAGE - Safety level of indicator materially improved by continuous self-checking of all circuitry. Intermittent faults or broken connections including lamps detected immediately by use of bi-stable electronic trip circuitry. Screened conductors prevent stray transients from impairing safety of system.