Rare Events

Motor switching inrush current

Motor switching inrush current: The recorded Current Waveform view, as shown in the caption picture above for a few milliseconds, shows normal oscillations with the 3phae system voltage and motor currents of a motor starting with soft starter for a Tyre Industry's Banbury Mixture Motor of rating 400kw, 660v, 3ph, 50hz. The RMS snapshot view, as shown in the picture below lasting about 7seconds, shows that after the initial millisecond starting oscillations, both the system voltage and motor currents drooped back to their rated values, which depicts a normal motor starting characteristics.

When Harmonic resonance strikes a grid

When Harmonic resonance strikes a grid, at its 33kV power distribution system, it results in a massive total voltage harmonic distortion, THDv magnification, within the affected power system at the grid supply zone. The order or number of individual voltage harmonics, are around the grid's natural resonance frequency range. It results in a large voltage oscillation, and fluctuations in the forms of simultaneous incidents of voltage sags and swells.

Self-extinguishing graph of a SF6 circuit breaker

Self-extinguishing graph of a SF6 circuit breaker: 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 waveform graph is the drooping characteristics of a 3phase system voltage and load currents, while switching off the 2nos, 2000A, 33kv, in parallel SF6 circuit breakers, of the EAF transformer.

Auto Transfer Switch ATS transitions in Data center

Auto Transfer Switch ATS transitions in Data center: A R&D Telecommunication and POP Internet Company had reported an UNUSUAL PROBLEM of Data Center Blackout, which infrequently, and out-of-the-blue, blacks out its entire data center load. In-addition, it had reported multiple incidents of alternator winding failures with its emergency DG. An inquisitive engineer always wondered why the Auto Transfer Switches are so overdesigned. Well, the answer lies in the "Waveform-and-RMS View" of this case study, as enclosed in the caption picture above.

Slip Ring Induction Motor start inrush current before Harmonic Filter

Optimization of Slip Ring Induction Motor in Fiberizer Drive in a Sugar milling unit - before HARMONIC FILTER INSTALLATION: The overall energy efficiency of a 5000TCD cane sugar mill with a 25mW co-generation power plant and 31.5MVA, 11kV/110kV grid synchronization transformer, improved by 14.3% to 19.1units per ton of cane crushed from its earlier level of 22.3units. How was the energy saving achieved? Well, in this case study we shall find that out with sugar industry's most sensitive and yet rough and tough drive load, the Fiberiser.