PQ safety is often overlooked, despite the danger Part of any power quality seminar material should cover the aspects of safety, especially for anyone who must connect/disconnect the voltage and current probes for power quality monitors.
How does electronic equipment know the difference? In past articles, we have covered the concept of harmonics, which are usually defined as frequencies that are integer multiples of the fundamental frequency.
220.19 Electric Ranges and Other Cooking Appliances Specifications for calculating branch-circuit, feeder and service loads are in Article 220 of the National Electrical Code. This article is divided into four parts: I. General, II. Feeders and Services, III.
Power quality problems lurk Stories about an increase in productivity in the commercial and industrial worlds attributed heavily to the growth in information technology (IT) equipment. In fact, this number has been put at $46 billion for the 2003 fiscal year.
220.19 Electric Ranges and Other Cooking Appliances Branch-circuit, feeder and service-load calculation provisions are in Article 220 of the National Electrical Code. While Part I is titled “General,” most of the first part pertains to branch-circuit calculations.
As a four-alarm fire raged through an old, vacant produce warehouse on Jan. 20, 2002, plumes of heavy black smoke filled the air in southeast Portland, Ore. Under spitting rain, 150 firefighters battled the blaze as it tossed large chunks of fiery debris onto streets as far as two blocks away.
A different kind of poison Every time I see the lights on a Christmas tree blinking on and off, I am reminded of the old adage, “One person’s medicine is another person’s poison.” Flickering lights in an office, factory or residential home can be more than an annoyance.
What do these statements have in common? • Lightning doesn’t strike the same place twice. • Electrical utilities correct a fault by sending a power surge to clear a short in a service line, transformer or other load grid short circuit.
Continuing to look at power quality’s biggest enemies As a continuation of last month’s article, here are a couple of additional “pictures” of the most popular PQ criminals for the office wall to help quickly identify what the squiggly lines mean and to find the source of problems.
Cooking Equipment Calculations, Part III 220.19 Electric Ranges and Other Cooking Appliances Article 220 of the National Electrical Code contains specifications for calculating branch-circuit, feeder and service loads.
Many changes have occurred to the National Electrical Code (NEC) since the first NEC was published on Aug. 31, 1897. Even though the electrical industry was in its infancy, this “first” NEC was remarkably insightful and has withstood the test of time.