A user`s perspective on the selection and application of equipment and techniques to deal with harmonics and other power quality issues
The proliferation of personal computers (PCs), programmable logic controllers (PLCs), energy management systems (EMS), microprocessor-based instrumentation, and other state-of-the-art electronic devices in an industrial plant setting has prompted a new awareness of the impact of power quality issues on the reliability of these systems and the ability to perform the desired tasks in an interruption-free manner. While it is common to consider the local power company as the source of all power quality problems, investigation has revealed that in many cases a significant portion originate in the plant itself from adjustable speed drives (ASDs), heater and lighting controls, copy machines, and even the switching power supplies of the computers and controllers themselves. Two of the greatest causes of harmonic distortion in today`s power systems are diode rectifiers and SCR switching devices. This distortion can be created by large solid state power supplies for AC and DC drive motors, small solid state controllers, and instrumentation and computer power supplies. Historically, most electrical motor and lighting loads were linear in nature, where current and voltage vary directly together. Electronic devices are now becoming a larger part of today`s total system load and with their non-linear nature, have become a large enough factor to have serious consequences in power distribution systems. Overheated neutral conductors, failed transformers, malfunctioning generators, false tripping of circuit breakers, and motor burnouts have been experienced, even though loads were apparently well within equipment ratings. Established maintenance procedures must be revised to reflect new techniques for dealing with these power quality issues.
- OSTI ID:
- 54720
- Report Number(s):
- CONF-941218--
- Country of Publication:
- United States
- Language:
- English
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