Device for determining a high-voltage potential in metal-encapsulated high-voltage switching installations and equipment

Claim 1

Apparatus for determining the high voltage potential on a conductor of a high voltage switching installation, the conductor carrying a high voltage and being supported by bodies of insulating material within a grounded metallic encapsulation, the apparatus comprising: a measuring circuit; an electrode disposed between the conductor and the encapsulation for delivering an electrical signal related to the potential on said conductor to said measuring circuit, said electrode including first and second electrode terminals situated at the ends thereof; and test circuit means including: first and second test circuit terminals, said second test circuit terminal being connected to said second electrode terminal; a circuit connected between said first and second test circuit terminals and including a source of energy and a current-sensitive means for providing an indication of current flow through said circuit and switch means for selectively connecting said first test circuit terminal to said first electrode terminal and to said encapsulation whereby current flow through said circuit when said switch means connects said first test circuit terminal to said first electrode terminal provides an indication that said electrode is not in open circuit condition and the absence of current flow through said circuit when said switch means connects said first test circuit terminal to said encapsulation provides an indication that said electrode is not in a short circuit condition.