Arrangement comprising a high voltage measuring capacitor

Apparatus for measuring voltage on a high-voltage conductor of a fully insulated, metal-encapsulted high-voltage switching installation wherein condition changes such as changes in pressure, temperature or the like can occur during the operation thereof;

• comprising:
• a surface electrode disposed adjacent said high-voltage conductor, said surface electrode and said high-voltage conductor cojointly defining a high-voltage measuring capacitor for detecting the voltage on said conductor, said measuring capacitor being susceptible to capacitance variations because of said condition changes in said installation;
• an auxiliary capacitor disposed within said high-voltage installation in the vicinity of said measuring capacitor and likewise susceptible to capacitance variations in response to said condition changes;
• evaluation circuit means incorporating said auxiliary capacitor for detecting variations in the capacitance of said auxiliary capacitor caused by said condition changes and for generating a signal indicative of said capacitance variations of said auxiliary capacitor thereby providing an indication that the capacitance of said measuring capacitor has likewise undergone a variation because of said condition changes;
• a low-voltage capacitor, said low-voltage capacitor being so arranged as to form a capacitive voltage divider with said high-voltage capacitor;
• and compensating means including a trimming capacitor which changes capacitance as a function of said signal and is so arranged relative to said low-voltage capacitor as to compensate for the changes in the divider ratio of said capacitive voltage divider resulting from changes in capacitance of said high-voltage capacitor.

Apparatus for measuring voltage on a high-voltage conductor of a fully insulated, metal-encapsulated high voltage-switching installation wherein condition changes such as changes in pressure, temperature or the like can occur during the operation thereof, comprising:

• a surface electrode disposed adjacent said high-voltage conductor, said surface electrode and said high-voltage conductor cojointly defining a high-voltage measuring capacitor for detecting the voltage on said conductor, said measuring capacitor being susceptible to capacitance variations because of said condition changes in said installation;
• an auxiliary capacitor disposed within said high-voltage installation in the vicinity of said measuring capacitor and likewise susceptible to capacitance variations in response to said condition changes;
• evaluation circuit means incorporating said auxiliary capacitor for detecting variations in the capacitance of said auxiliary capacitor caused by said condition changes and for generating a signal indicative of said capacitance variations of said auxiliary capcitor thereby providing an indication that the capacitance of said measuring capacitor has likewise undergone a variation because of said condition changes;
• a low-voltage capacitor, said low-voltage capacitor being so arranged as to form a capacitive voltage divider with said high voltage capacitor;
• and compensation means including an amplifier circuit which is connected to said low-voltage capacitor and to said evaluation circuit, said amplifier circuit being so arranged as to undergo changes in gain which compensate for changes in output caused by changes in the capacitance of said high-voltage capacitor.