Runaway power oscillation and core saturation

Runaway power oscillations and core saturation: A motor starting with soft starter of a Tyre Industry's Banbury Mixture Motor of rating 400kw, 660v, 3ph, 50hz. The recorded RMS graph view, lasting totally about 6secs, shows high oscillations at the starting instant with the 3phae system voltage and motor currents, which lasted for a longer time than the usual time of a few milliseconds. Thereafter the system voltage and motor currents did not droop back to their rated values, which happens with normal motor starting.

Transformer switching inrush current and harmonics

Transformer switching inrush current and harmonics: The Power System measurements were carried-out at 33kv primary bus, across a 150mva, 33kv/1120v, Electrical Arc Furnace Transformer, supplying to a 180 Ton EAF Furnace, connecting through a set of 2nos. 2000A, 33kv, in parallel, SF6 Circuit Breakers. The captured current waveforms and harmonics bar graph, as shown in the caption picture above, is a rarity since it is shot/recorded at the same microsecond/ millisecond instant of a transformer switching ON.