Thumping Sounds in the Closet
By Dranetz-BMI

Elevator control panels for the lower zone mid-rise elevators were on the nineteenth floor of a forty story office building in a large Midwestern city. It was fed with 480V transformer on the same floor, with the feeders to the controls rated at 800A.

Excessive noise and vibration of the feeder wires and conduit were noticed on a number of upper floors.

There's Gold in Those Waveforms
by: Richard P. Bingham, Dranetz-BMI

In the present business climate, companies are under constant pressure to increase profitability by increasing productivity, maximizing assets utilization, and doing more with less (less people, less materials, less time). Much of this has been made possible by the increase in use and reliance on information technology (IT) equipment, such as personal computers (PCs), networks, and electronic communication equipment. Increase in consumption of electrical energy is being countered by the increased use of more efficient power supplies, which are found in IT equipment, programmable logic controllers (PLCs) and adjustable speed drives (ASDs). As the IEEE Std 1100-1992, known as the Emerald Book, points out, this equipment "can be both a contributor to and a victim of powering and grounding incompatibilities in the power system".

Having more problems that must be solved in a shorter time period with less people has forced many companies to outsource some or all of their electrical equipment preventative and emergency maintenance work to electrical contractors. A significant percentage of this work involves dealing with problems caused by power quality disturbances or phenomena interacting with the building's electrical infrastructure and loads. With a basic understand of the most common type of power quality phenomena, electrical contracting firms can provide a very valuable service to your customers, who are then better able to meet their financial objectives.