Aleksas Žalpys Chief State Inspector Products Control Department STATE NON FOOD PRODUCTS INSPECTORATE UNDER THE MINISTRY OF ECONOMY OF THE REPUBLIC OF LITHUANIA

 An electrical ballast is a device intended to limit the amount of current in an electric circuit. A familiar and widely used example is the inductive ballast used in fluorescent lamps, to limit the current through the tube, which would otherwise rise to destructive levels due to the tube's negative resistance characteristic.currentelectriccircuitfluorescent lampsnegative resistance  Ballasts vary in design complexity. They can be as simple as a series resistor or inductor, capacitors, or a combination thereof or as complex as electronic ballasts used with fluorescent lamps and high-intensity discharge lamps.resistorinductorcapacitorsfluorescent lampshigh-intensity discharge lamps

Ballasts limit the current through an electrical load. These are most often used when a load presents a negative (differential) resistance to the supply. If such a device were connected to a constant-voltage power supply, it would draw an increasing amount of current until it was destroyed or caused the power supply to fail. To prevent this, a ballast provides a positive resistance or reactance that limits the current. The ballast provides for the proper operation of the negative-resistance device by limiting current. A gas-discharge lamp is an example of a device having negative resistance, where after lamp ignition, the increasing lamp current tends to reduce the voltage "dropped" across it, (if it is in series with other circuit elements). Ohms Law states R = V / I so R is effectively decreased if V decreases or stays constant while I increases. The resistance is lowered by increases in current which is opposite to the normal effect and therefore called "negative" resistance. In some cases a simple series current limiting reactor (inductor) is sufficient to act as a ballast for a lamp. Ballasts can also be used simply to limit the current in an ordinary, positive- resistance circuit. Prior to the advent of solid-state ignition, automobile ignition systems commonly included a ballast resistor to regulate the voltage applied to the ignition system. Series resistors are used as ballasts to control the current through LEDs.

The indoor lighting is a combination of external daylight and artificial lighting, which should be considered both in building design and in lighting design. Results of those will have in turn impact on mechanical design. The good energy efficiency comes from good understanding of user requirements and design applications. Proper surface colours and reflectance, light sources, luminaire and lighting controls are essential for user’s satisfaction, well-being, productivity and energy efficiency. The European Commission has introduced The Energy Labelling Directive, which is a legislative framework for requirements and performance levels for standard lighting bulbs The directive requires that products be labelled to show their energy power consumption in such a manner that it is possible to compare the efficiency with that of other makes and models. Energy rating to classes A – G are used, where the class A represents the best practice in the market and class D the average energy use. CE-marking a product is not permitted unless it complies with the directives, which apply to it.

The European Standard EN fixes the measuring methods for the total input power of the ballast –lamp system. Using this European Standard as a basis, CELMA (the European Federation of the National Association of the manufacturers of luminaires, control gear and lampholders) has fixed both energy classes and limit values for the ballast-lamp combination of the common fluorescent lamps. The CELMA “Energy Efficiency Index” system contains 7 classes: A1, A2, A3, B1, B2, C and D. The guideline is valid for mains-operated ballasts for fluorescent lamps. The EEI system comprises of the following lamp types: Tubular fluorescent lamps T8 Compact fluorescent lamps TC-L, TC-D, TC-T and TC-DD The International Standard IEC :2011 defines a measurement and calculation method of the total input power for controlgear - lamp circuits when operating with their associated fluorescent lamp(s). The calculation method for the efficiency of the lamp controlgear is also defined. This International Standard applies to electrical controlgear lamp circuits consisting only of the controlgear and the lamp(s). It is intended for use on a.c. supplies up to V at 50 Hz or 60 Hz.

Different maximum values of system power input including the light source and the ballast have been defined for common lamp types. As an example the seven EEI classes for a 36 W T8 (T26) fluorescent lamp are the following: ClassDescriptionSystem power Dmagnetic ballasts with very high losses> 45 W Cmagnetic ballasts with moderate losses ≤ 45 W B2magnetic ballasts with low losses ≤ 43 W B1magnetic ballasts with very low losses ≤ 41 W A3electronic ballasts ≤ 38 W A2 electronic ballasts with reduced losses ≤ 36 W A1 dimmable electronic ballasts ≤ 38 /19 W (at 100% -25%) According to European Directive 2000/55/EC today only the classes A1 though B2 will be valid in of the voluntary CELMA EEI rating.

There are choice of several types of light sources with different features for the different lighting applications. When selecting the bulb, attention should be put a.o. in light colour, colour reproduction, energy efficiency and service life. Also controllability and operating temperatures of the bulb are important. Light output of light sources vary, among others, with type, size, voltage and operating hours. Light output (lumen/W) of some types and sizes are shown in table below. Lighting efficiency vary very much by the type and in some degree by the size. Some of the products have the CE energy rating markings to ease the selection.

Most of the new energy efficient lighting systems have been designed to operate the Standard 40-watt F40 fluorescent lamps. The lighting industry has introduced a 34- watt F40 krypton-filled lamp that will draw less power from the same lighting equipment (ballasts) than the 40-watt lamp. These lamps are being used more and more as retrofits as well as in new construction. Ballast Factor: The ballast factor is a metric that defines the relative light output provided by a ballast-lamp system with respect to the manufacturers rated light output for the lamp specified in their catalog.

Filament Voltage: The filament voltage applied to lamps by most electronic ballasts (2.1 to 2.4 volts) is less than that applied by a standard CBM core-coil ballast (3.4 to 3.6 volts). Some electronic ballasts remove all of the filament voltage during operation. This effect will tend to reduce lamp life, but it will also reduce the power and result in a more efficient system. The latest electronic ballast designs, labeled A to G, no longer remove all of the filament power. Lamp Current Crest Factor: At 60 hertz the lamp current crest factor is greater for the 34-watt lamp than for the 40-watt lamp. There is virtually no difference in lamp current crest factor for the two types of lamps with the electronic ballasts. Generally, the crest factor is greater for the electronic ballast systems. However, lamp current crest factors range from 2.2 to 1.3. The higher lamp current crest factors, above the 1.7 ANSI recommended limit, could contribute to reduced lamp life.

Open Circuit Voltage: The measured open circuit voltage for the electronic ballasts is considerably greater than that measured for the standard core-coil CBM ballast. The average and the range of values measured for the electronic ballast. The higher open circuit voltage will permit the lamps to start in a cooler ambient temperature. However, at higher ambient temperatures the actual starting voltage will be considerably less than the available open circuit voltage, especially if the filaments are suitably heated. Open Circuit Voltage Crest Factor: The range of values for the open circuit voltage crest factor for the electronic ballasts. The average values are about the same as those measured for the core-coil ballast. Some electronic ballasts have a value slightly above the recommended maximum of 2.0. The higher crest factors increase the degradation of the filaments at starting.

Flicker: The range of flicker measured for the electronic ballast operating both types of lamps. In general, the percent flicker is much lower when the lamps are operated at high frequency (with electronic ballasts) than at 60 hertz (with a core-coil ballast). In fact, some lamps operated at high frequency with an unmodulated waveform have no flicker. A few electronic ballasts have fully modulated wave shapes at 60 hertz which results in a percent flicker as high as that which occurs with the core-coil ballast. The 34-watt lite white lamps have a lower percent flicker than the 40-watt cool white lamps, because of the extra quantity of a yellow-emitting phosphor in the mix. The red- and yellow-emitting phosphors generally have a larger persistence than the blue emitting phosphors. Light Output: Lighting designers need to know the light output for each ballast-lamp system in order to select the optimum lamp-ballast to meet their illumination needs. The range of light output from the lamps operated with the different electronic ballasts is about 10 to 15 percent. The change in the light output for all types of ballast (core-coil and electronic) operating the 34-watt F40 lamps is about 13 percent lower than the output for ballasts operating the 40-watt cool white lamp.

System Efficacy: The average efficacy is 79 to 80 lumens per watt for the electronic ballast systems with either lamp. Some of the ballast designs achieves an efficacy of 83 to 84 lumens per watt. It is important to notice the very slight increase (~1 percent) in the system efficacy for the 34-watt system, even though the 34-watt lamp is about 6 percent more efficacious than the 40-watt lamp. Thus, the system efficacy is about the same for a ballast operating either lamp. In general, the electronic ballast systems are 20 percent more efficient than the core-coil systems operating the same lamp.

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