In order to reduce electric energy consumption, the use of CFLs, also known as energy saving lamps, is being strongly recommended. Utilities have also expressed concern since they have been actively recommending their use in their demand-side management (DSM) programs through giveaways and rebates.
CFLs are non-linear consumers. Non-linear consumers produce harmonic currents which flow through the electric power network. They cancel out in generators and other consumers. The results of those currents are harmonic voltages. Both harmonic voltages and canceling out harmonic currents affect performance of other consumers connected to the electric power network. Because most electrical systems were designed for linear voltage and current waveforms (i.e. nearly sinusoidal), excessive nonlinear loads can cause serious problems such as overheating conductors, transformer and capacitor failures as well as malfunction of electronic equipment. The magnitudes of harmonics generated by the CFLs vary between manufacturers and between ranges of lamps from the suppliers.
At present, no serious power quality problems have been reported with the use of CFLs. One reason may be that these lamp systems presently comprise a very small portion of the lamp market and are usually only a small portion of a building’s load. However, if their use continues to escalate such that they are a major portion of a building’s load power, quality may suffer. In fact, the poor power factor and/or high harmonics might limit the use of CFLs as an efficacious replacement for the incandescent lamp.
Although the CFL lamps are generally cost effective, their high initial cost compared with the incandescent lamp has limited their acceptance. Thus, manufacturers have introduced the simplest ballast (magnetic and electronic) designs. These low-cost designs employ neither power factor corrections nor harmonic filters.
1.1 CFLs Characteristics:
CFLs have been developed from classical fluorescent discharge lamps, which use inductive "ballast" for their normal operation and a starting capacitor to ignite the gas in the lamp. The inductive ballast enables the electric arch to burn more smoothly and must be thus connected in series with the lamp all the time. This produces a very poor power factor of these lamps. A relatively low frequency of gas ignitions can have a disturbing effect and can produce light flicker. CFLs also use ballast, too, which is in this case an electronic circuit that feeds the gas-filled fluorescent lamp with an alternating voltage of a few kHz. This ensures smoother operation and reduces light flicker. Basic distinctions of CFLs from other lamps : • Smaller active power consumption (approx. by factor 5) and less heat losses (approx. by factor 15) for the same light flow compared to the classic incandescent lamps. • They are non-linear devices and inject harmonic currents into the network. The character of the fundamental harmonic (50 Hz) is capacitive. • The use of the thyristor-controlled dimmers is mostly not applicable due to the way the lamp operates. However, the ability of some CFLs to control the light flow is limited. • They need up to a few minutes to achieve the rated light flow. At low temperatures they might not ignite at all. • They are more resistant to voltage fluctuations which causes light flicker (approx. by factor 5) than classic incandescent lamps. • Their life span may be in some special cases up to 20 times the life span of the classic incandescent lamps. • The total energy needed to produce and distribute them to the customers may be up to 20 times the energy needed compared to the classic incandescent lamps.
Harmonic problems are almost always introduced by the consumers’ equipment and installation practices. Harmonic distortion is caused by the high use of non-linear load equipment such as computer power supplies, electronic...
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