【 Weak current College 】 electronic ballasts in stage computer application of lighting

With the extension of the green lighting, a.c. supplied electronic ballasts for start, entered the 1990s, various gas discharge lamp with electronic ballast and a variety of new electric light source in the world are emerging, formation called the "green lighting" of new industries. Gas discharge lamp as the main stage computer lamp light source, configure Exchange electronic ballast is a general trend.
Conventional inductive ballasts in use has significant drawbacks. When the AC over zero, lamp will result in the fire, which will make the lamp flashes of light produced 100Hz, thereby reducing the lamp's luminous efficiency. At the same time, the inductive ballasts to avoid core vibration to be populated with asphalt, results at run time to produce audio "humming" sound. In addition, inductive ballasts heavy, usually a 1200W of inductive ballast weights 13Kg; and inductive ballast loss, fever, severe; voltage fluctuations, the lamp current fluctuations as well, when the power supply voltage is increased by 10%, the lamp current increased 17 per cent, which greatly improves the lamps and the life of the lamp.
Electronic ballast and traditional inductive ballasts compared to commonly used, have many advantages, such as increased lamp and circuit efficiency, energy saving, easy-to-achieve dimming control, no stroboscopic, non inductive ballasts unique "humming" sound, etc. Inductive ballasts faults in electronic ballasts in most of them can be overcome. Electronic ballast is actually a high frequency of self-excited Oscillation (he dared) converters, electric discharge lamp is a converter of load, load circuits are often set up a series resonant circuit.
The advantages of electronic ballasts are reflected in the following areas:
1, high-frequency self-excited Oscillation (he dared) converter and the series resonance, its load can apply various gas discharge lamps simply change the resonance circuit capacitance, inductance parameters to select suitable Q value, can drive various specifications of the gas discharge lamp load, Kai-voltage lower fluorescent lamps, or restart-voltage high pressure sodium lamp, metal halide lamps, etc.
2, the series resonance load circuit voltage supplied to the fluorescent tube is high frequency sine wave, sine wave voltage driving lamp makes electrode loss and high frequency arc stability; and relative frequency will increase 15% light emitting efficiency.
3, high-frequency converter and the series resonance inductance combination, for discharge lamp equivalent from a low impedance voltage source into a high-impedance current source for choke and constant power supply.
4, in the high-frequency converter power grid side access power factor correction (active or passive), the power grid side power factor improvement to 0.95 above, even up to 0.99.
5. lamp used in the process of aging, aging will gradually be given electrode activity element of emission performance continues to decay, the ageing lamp luminous flux is also declining. However, the electronic ballast of resonant circuits can consistently providing compensation to the lamp, the lamp maintain electric energy efficient lighting, lamp service life is extended.
6, the electronic ballast on short circuit, open circuit, overvoltage, overcurrent and overtemperature protection easier, especially computer lamps in the application process dimming control features can be fully expressed.
7. in the volume and weight, the electronic ballast also have very significant advantages, the greater the advantage of power.
Electronic ballast is not without flaws, the cost is high, the circuit complex, on the production process, specification has strict requirements, such as power supply input current harmonic content and line power factor is two very important indicator. International Electrotechnical Commission has also formulated a IEC555-2, IEC61000-3-2 and other regulations, EN60555-Europe has developed 2 regulations, the Chinese Government has also developed national standards GB/T14549-93, and other regulations on electrical devices of voltage, current waveform distortion made specific restrictions and regulations.

With the switching power supply, electronic ballast, contributed to PFC (power factor correction) technology. PFC circuit is the basic principle of work through the control circuit forced input current tracking input voltage, input current sine and synchronize with input voltage, it functions as a pure resistance. Market better electronic ballast factor greater than 0.95 (around 0.98), harmonic content of less than 20 per cent of the total, the third-harmonic and other times the harmonic content of less than 10 per cent of the total, lamp current wave ratio less than 1.7, EMC IEC, cheap electronic ballast factor generally does not exceed 0.65, input current total harmonic distortion THD of up to 100 percent. It is not reaching the standard of electronic ballasts in use can cause any harm?
Electronic ballast for input supply current harmonic content is too high, if you are a used alone, the damage may not be able to clearly show it. But if the millions of intensive use, harmonic currents produced by the will to power system causing serious pollution, affecting the entire power system's electrical environment, including the power system itself and the majority of users. Excessive current harmonic makes the generator and motor generate additional power loss, causing fever; for reactive power compensation capacitor, give rise to resonance and harmonic current too high, causing power capacitor due excessively load or overvoltage damage; harmonic current increases the transformers and power loss; current harmonic content of electronic ballasts in the way of a power-intensive installation, three-phase four-wire line currents of power supply system has increased dramatically, far higher than the phase current, causing a midline overload, and can easily cause damage to electronic ballasts in a batch. In serious cases, will cause a fire, resulting in significant economic losses. Therefore, in terms of ensuring the safety of electric power system operation or from a protected user equipment and physical security, must be strictly limited current harmonic content, harmonic to reduce the serious harm caused by pollution.
Based on the above industry standards and strict technical requirements, many lighting factory also has a series of technical difficulties does not break, plus the cost is high, so many computer lamp manufacturers still using inductive ballast. While chaiyi light company in 2002 has boldly enabled switching power supply, electronic ballast, in stage lighting lineIndustry became the first person to eat crabs. Although early encounter some ups and downs, but after several years of experience and continuous improvement, chaiyi in this road yueshun. In 2008, chaiyi purchased 40 million detection equipment, designed to detect electronic ballasts, switching power supply of related technical indicators, to ensure that each batch of product shipment. Chaiyi light has now become a stage lighting industry "green lighting" leader.