High voltage measurement transducer for gas insulated HV switchgear - has coil in recess of internal conductor having transmission circuit for conversion of digitised electrical signal to light signal

摘要

A high voltage metal enclosed switching installation with gas insulation is fitted with a current transformer whose metering coil (45) is situated in an annular recess (44) in one of the hollow internal conductors (11). The conductors (11) are supported away from earth (10) by hollow insulators (16) and the coil (45) output is digitised in an A/D converter (25) which is itself energised from a capacitive potential divider (30-35). The resultant signals modulate a light source (26) whose light output is conveyed via a spiral optic fibre (27) through the insulator (16) for evaluation by an output unit (28). ADVANTAGE - Device is small, has high accuracy and is easily installed in existing installations. Energy supply to electronics is inherently available at all times when HV conductors are operational. Spiral routing of fibre-optic provides long creepage path to earth, giving maximum protection against tracking.