Siemens Aktiengesellschaft

Bernd Rost

Wilfried Kuhl

Leonhard Klug

Wolfgang Schilling

A device for measuring the internal pressure of an operationally built-in vacuum switch which comprises a vacuum switching tube having a switching chamber and switch contacts as well as an associated drive for the contacts. For the measurement of the pressure, a cold-cathode discharge (so-called Penning effect) having crossed electric and magnetic fields is used, wherein the electric field is applied, for instance, between at least one of the switch contacts and a metallic wall of the switching chamber or a condensation shield disposed in the chamber and permanent magnets are used for generating the magnetic field. The permanent magnets are realized in the form of rods and have pole pieces formed such that the pole pieces encircle the switching chamber. A magnetic field is formed which is applied directly in the longitudinal direction to a circumferential section of the cylindrical switching chamber. In order to measure the pressure inside the vacuum switching tube built into a switching installation, the voltage drop across a resistor disposed in series with a d-c source and the switch is measured. The voltage drop corresponds to the ionization current, which is dependent on the gas pressure in the chamber. The pole pieces of the permanent magnets extend around the switching chamber and fix the magnets around the switching chamber during the measurement. The sensitivity range of the measurement can be influenced by the number of permanent magnets used.

Growing community of inventors

Erlangen, Germany

Bernd Rost