A thunderstorm rolls over a light rail line. Lightning hits a catenary pole a mile from the substation. The surge races along the overhead wire toward the rectifier at nearly the speed of light. Smaller spikes from breaker switching and line faults arrive many times a day. Without DC surge protection, that energy lands on…
An aggregate quarry’s utility bill shows a power factor of 0.78 for the month, along with a penalty line item. The plant has not added any equipment. Its crushers, conveyor drives and pumps simply run at partial load most of the day. Induction motors draw reactive power to build their magnetic fields, and lightly loaded…
A roof bolter operator is drilling at the face. Methane from a cutter seam starts to bleed into the entry. It has no smell and no color, and the air feels exactly the same as it did a minute ago. A few hundred feet back, a belt roller has seized and begun to smolder, giving…
