Tag Archives: Electrical Power Quality

What do you mean by Quality of Electrical Power?

Quality of Electrical Power determines electric power fitness to consumer devices. Frequency phase and voltage’s synchronization in turn allows functioning of electrical systems. This is in intended manner with no significant life loss or performance loss. Terms are used for describing electric powers. This drives electrical load and ability of load for proper functioning. With no power proper, electrical loads or electrical devices might malfunction, prematurely fail or having no operation at all. There are lots of ways where electrical power is poor quality. There are lots of causes of poor like this power quality. Industry of electric power in turn comprise of AC power, electricity generation, power distribution electrically, and ultimately electric power distribution. This is situated at premises of end users of electrical powers. Electricity moves by means of wiring systems of end users till load is reached. System complexity moves electrical energy from production point to consumption point. It is combined with demand, weather and generation variations and different factors providing lots of opportunities for compromise in supply quality.

Whilst “power quality” is term convenient for many, but it is voltage quality rather than electric current or power which actually is described by terms. Power simply is energy flow and load demanded current which cannot be largely controlled. Quality of Electrical Power is described by parameters values set like harmonic contents in AC power waveforms, service continuity, transient currents and voltages and variation in magnitude of voltages. Power quality is thought as having problem of compatibility. It is equipment being connected to grids. It is compatible with grid events. Power is delivered by grids. This includes events having equipment compatibility with connections. There are 2 solutions at least for compatibility problems. In these cases there is power clean up either or making tougher equipment. Data processing tolerance equipment to variations in voltages is characterized often by CBEMA curves. It gives magnitude and duration of variations in voltages which could be tolerated. AC voltage ideally has been utility supplied as sinusoidal. This has frequency and amplitude provided by standards nationally (in cases of mains) or specifications of system (in cases of power feeds no attached directly to mains). There are impedances of 0 ohms in each and every frequency.

No power source real-life is ideal. It deviates generally in these ways following: Variations in RMS voltage or peak voltage are important both to various equipment types. When RMS voltages exceed nominal voltages by 10% to 80% for 0.5 cycles to 1 minute, event is known as “swell”. “Sag” or a “dip” (equivalent terms) is situation opposite. RMS voltages are below nominal voltages by 10% to 90% for 0.5 cycles to 1 minute. Repetitive or random RMS voltage variation is in between 90% and 110% of nominal. This produces phenomenon called “flicker” in equipment of lighting. This flicker is visible with rapid changes of light levels. Characteristic definition of fluctuation of voltages produces light flicker objectionable being subjected to research on-going. Very briefed abrupt voltage increase known as “surges”, “spikes” or “impulses” caused generally by vast inductive loads. These are turned off or very severely by lighting. Power conditioning is modification of power for improving its quality. Power supply uninterruptible is used for switching off of power mains in case there are temporary or transient conditions on lines. Cheap UPS units, however, creates poor quality power by themselves. This is akin for imposing low amplitude and high frequency square wave atop sine wave. UPS high quality units utilize topologies of double conversions that break down AC incoming power to DC. It charges batteries. Then it re-manufactures AC sine waves.


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