Posted May 26 2012 by Sufi Shah Hamid Jalali in Energy Efficiency, Lighting with 2 Comments
on Electrical Engineering Portal
Original Source: Wolsey, Robert, Power Quality, Volume 2, Number 2, February 1995 (Lighting Research Center (LRC) and Power Quality)
Concerns about the effects of lighting products on power distribution systems have focused attention on power quality. Poor power quality can waste energy and the capacity of an electrical system; it can harm both the electrical distribution system and devices operating on the system.
There are many elements in a power system that affects two major parameters; power factor and harmonics. Electric motors, some lighting fixtures, transformers and other inductive and capacitive appliances introduce reactive power to the system, and thus involved in damaging the power factor. These components need reactive power to work.
Nonlinear loads like UPS, computer systems, fluorescent fixtures, CFLs, digital electronics, etc. are distorting current waveforms and introducing harmonics to the power system.
This technical article will help lighting specifiers and consumers better understand power quality, so that they can more confidently select energy-efficient lighting products. Continue reading →
Vacon UK – Using variable speed drives (VSDs) is a great way of saving energy but, if your VSDs are more than five years old, it’s time to take another look at them, says Stephen Takhar, Managing Director of ac variable speed drive expert, Vacon UK.
For the last decade, the technical press has been awash with stories about the energy savings that can be made by fitting VSDs. The stories are true, which is why many companies have already installed VSDs. When engineers in these companies see the VSD energy saving stories, they probably think they’ve been there and done that, but are they justified in sitting back and enjoying the glow of a job well done? That depends on the age of their VSDs. If they’re just a few years old, it’s unlikely that further action is needed. But if the VSDs are over five years old, it’s a different story. Continue reading →
As a Power Quality Expert, who should you be close to professionally
As a Power Quality Expert, it is important to have the right contacts in order to get the right information to specify an effective solution. Here are a few of you important contacts and a list of questions that you may want to ask. Continue reading →
Faculty of Engineering, Sohar University, P.O. Box 44, 311 Sohar, Oman
Academic Editor: Hadi Y. Kanaan
A growing number of harmonic mitigation techniques are now available including active and passive methods, and the selection of the best-suited technique for a particular case can be a complicated decision-making process. The performance of some of these techniques is largely dependent on system conditions, while others require extensive system analysis to prevent resonance problems and capacitor failure. A classification of the various available harmonic mitigation techniques is presented in this paper aimed at presenting a review of harmonic mitigation methods to researchers, designers, and engineers dealing with power distribution systems. Continue reading →
I have found another interesting article that I would like to share with you.
Author: Nicolás Louzán Pérez, Manuel Pérez Donsión1 1Department of Electrical Engineering E.T.S.I.I., Vigo University Lagoas – Marcosende, 36202 Vigo (Spain) e-mail:firstname.lastname@example.org
Article presented at INTERNATIONAL CONFERENCE ON RENEWABLE ENERGY AND POWER QUALITY (ICREPQ’03)
The classical disruptions present in the distribution network and inside the industrial plants, the influx of digital computers and other types of electronic controls used by industries to achieve maximum productivity, the increase of the power based on renewable energy and the reduced redundancy in lines and substations, has a negative impact over the medium and low voltage distribution network power quality, as well as in the industrial customer installations. Continue reading →
I found this excellent paper written in 2000 and decided to share with you.
Daniel J. Carnovale, P.E.
Eaton | Cutler-Hammer
Moon Township, PA
Thomas J. Dionise, P.E.
Eaton | Cutler-Hammer
Thomas M. Blooming, P.E.
Eaton | Cutler-Hammer
This paper assumes that the reader has some basic knowledge of power system harmonics. As a simple refresher – the general acceptable explanation is that harmonic currents flow or are “sourced” from loads and create voltage distortion (or harmonic voltages) as they pass through upstream power system impedance components such as cables, transformers, and generators. In general, the further away from the source of harmonic currents (i.e. the loads), the less voltage distortion you will see. Certainly exceptions exist and harmonic voltages may be “produced” by some equipment (some generators, for example) but the general discussion of this paper deals with standard considerations when dealing with typical harmonic producing loads in commercial and industrial power systems. Continue reading →
Among the most frequent disturbances, voltage dips and short interruptions are at the top of the list and they may interfere with proper operation of a large number of electric, electronic equipment and even entire processes. Thus, residential, commercial and industrial loads may be more sensitive to common network disturbances if precautions are not taken in the design stage. This technique can be used to solve issues with loads being affected by any type of Power Quality disturbances, coming from the supply or generated by other loads. An article on how to correct Power Quality problems generated by loads will come soon.
Depending on the type of equipment malfunctions or failures, different protection devices or ride through techniques can be used to economically increase immunization to disturbances at acceptable levels.
Several steps are needed to determine whether the implementation of a solution is required. The next figure illustrates an effective step-by-step Power Quality problem solving technique for large commercial or industrial loads affected by disturbances. Consequently, the problem solving process is a lot simpler for smaller loads. For now we will concentrate our efforts on larger loads.