Gas-insulated switchgear with voltage transformer and optical measuring element

摘要

The voltage transformer has a measuring element in the electrical field between an internal conductor and an external conductor of a metal-encapsulated, gas-insulated switchgear. The measuring element includes a Pockels crystal, a crystal of transparent material which, under the influence of the electric field, influences polarized light that is radiated through on account of the Pockels effect. The Pockels crystal has two parallel walls transverse with respect to the field lines. A first deflection prism, which deflects a light beam through 180 DEG , is disposed on the crystal face at the high-voltage end. Several optical elements are disposed at the face on the low-voltage side. The optical elements include a light input coupler for polarized light and two light output couplers. The reflected light beam impinges on a beam splitter, which splits the light beam into two partial beams. The first partial beam radiates firstly through a quarter-wave plate and then through a first analyzer. The second partial beam radiates through a second analyzer.