Optical and electrical investigation of spark behaviour in DC Low-voltage switchgear during contact separation

Inhalt:
The paper presents a new model switch for the investigation of spark / arc behaviour in low-voltage switchgear. A laboratory setup with a rotating and a fixed electrode is analysed, whereby a constant contact separation speed is realised. The voltage across the contacts is evaluated along with the current and contact position to determine other electrical quantities, such as the electric field strength in the spark, as well as the sheath voltage. The constructed model was designed to investigate the correlation of the electrical and optical magnitudes. A series of experiments were conducted with currents ranging from 0.5 A to 4.45 A and for contact opening speeds at 0.27 m/s, 0.66 m/s and 1.38 m/s with a constant current source. Furthermore, spectrally selective photodiodes are used. The spark emission in a broad spectral range is compared with the power per unit length in the spark.