Energy Efficient Lighting- Compact Fluorescents on 120 VAC George Patterson copyright1990 by George Patterson Compact fluorescent lights are one of the most energy efficient lamps available in the market today. They produce 3 1/2 times more lumens per watt than incandescent lights and 7 to 13 times the lamp life as a standard "A" type incandescent. The lamps use 70% less power than standard incandescent. Modern types use high frequency electronic ballast and produce silent, flicker-free light. These lamps are color correct. They produce light that is a very good imitation of daylight. We are seeing a revolution in lighting! Compact Fluorescent Lamp Data INSERT COMPACT FLUORESCENT TABLE The data in the table shows performance data for six compact fluorescent lamps and two types of incandescent lamps. Lumens is a unit of light intensity and ranks the lamps by brightness (the higher the lumen value the more light the lamp produces). Lumens per watt shows how efficient the lamp is, note that the compact fluorescents are about six times more efficient than incandescents. The lifetime (in hours) is rated by the manufacturer assuming that the lamp remains burning for three hours when switched on. Minimum starting temperature is just that, the lowest temperature at which the lamp will reliably start. Color temperature is a scientific system for measuring the spectral output of a light producing object. In the color temperature scheme, the object color is related to a black body at a certain temperature in degrees Kelvin (øK.). The color rendition index is more easily understood. The color rendition index of daylight is 100 by definition. The closer a lamp's color rendition index is to 100, the closer its color is to daylight. OK! Are all of these deals real? How do they apply to real life? The fluorescent light as a system The lighting fixture is truly an energy system with four elements - 1) Input power, 2) Ballast, 3) Starter, and 4) Fluorescent tube. The efficiency and performance of the system is dependent on the interaction of all four elements. Change any one element and the light's performance and efficiency changes. INSERT ILLUSTRATION The reality of lighting is that we are not going to get something for nothing. Of course, in trying to do so we are likely to take ourselves to the cleaners. There is no substitute for doing our homework and making decisions based upon actual experiences. The 10,000 hour life figure quoted for most compact fluorescent tubes is just a starting point. The truth is that we may get anywhere from 2,000 to 20,000 hours from the same tube depending on the ballast type and operating environment. The light output from a 13 watt compact fluorescent tube may be 900 lumens at 75ø F (100%), 720 lumens at 120ø F. and 450 lumens at 40ø F. This is especially a problem where housings and lighting fixtures trap heat inside, or they are used outdoors in the cold.. A typical graph of the operating temperature characteristics is shown in figure 1. Note that the efficiency we seek so dearly is effected by the position of the base. INSERT GRAPH Ballast and tube life on inverters ( square wave ) may be cut in half compared to use on true sine wave for 120 VAC applications. On modified sine wave inverters there is not known to be a problem, but the jury is still out. Tube Life and Starting The electronic ballast may deliver promised efficiency, but the design of the starting circuit is critical. Some compact fluorescent tubes have built in glow discharge starters, while others use pre-heat filaments for starting. Pre-heat filaments require external starting circuitry. Life of compact fluorescent tubes designed for use with external starting circuits (rapid start, pre-heat, and electronic ballasts) is determined by the design of the starting circuit. The life of a fluorescent tube with built in glow discharge starter is primarily determined by the life of the starter. Starter life in these tubes varies widely with ballast design. If the fellows that designed the ballasts did a good job, then the starter will last the 10,000 hour life of the tube. If the ballast is not properly designed we can expect life times as short as 2,000 hours. Ballasts The newly developed high power factor coil capacitor ballasts for 120 VAC have energy efficiencies similar to electronic ballasts. When operated at normal AC line frequency (60 Hz.) the color temperature is 2700ø K. By operating compact fluorescent lamps on an electronic ballast at high frequency, 25 kHz to 35 kHz, the lamps phosphors are about 14% to 17% more efficient at producing light and flicker is eliminated. The color temperature drops from 2700øK to about 2300øK.. Very few residential ballast designs address the power factor requirements imposed by fluorescent lamps. Power factor relates to the lag between current and voltage and values less than 1.0 translate into wasted energy. Some ballasts have power factors as high as 0.9, but many fall short with values as poor as 0.2. Normally, coil capacitor ballasts have a power factor of 0.2 to 0.4, however, high power factor (HPF) designs achieve values as high as 0.9. Electronic ballasts usually have power factors above 0.6 and the more expensive and bulky designs above 0.9. The OSRAM Corporation, A Siemens Company (the same people that purchased ARCO Solar!), is one of the industry leaders in both compact fluorescent lamp and electronic ballast manufacturing. OSRAM has a line of 12 VDC and 120VAC/DC ballasts that are available only in Europe. These commercial grade electronic ballasts have a power factor greater than 0.9., and will soon be available in the USA in 5 to 26 watt sizes. Dulux EL Electronic Light Bulbs Residential grade OSRAM DULUXtm EL lamps (Electronic Light Bulbs) are available in the USA right now. These are for retrofit applications and have medium bases that replace incandescent light bulbs. These lamps may be used on inverters at 120VAC and there is no hum! The power factor for these DULUXtm Electronic Lightbulbs is 0.6 to 0.7. Its built in ballast is designed with a full wave bridge rectifier capacitor input filter followed by a 35 kHz oscillator to drive the fluorescent tube. All of this is integrated and the expected tube life and ballast life is well matched. As a result of this design, these electronic light bulbs may be operated on DC or 120VAC. Since the capacitor acts as a peak detector of the 120 V RMS AC, the DC required would be around 165 V. This may be only interesting, but I thought that I would mention it. Also, these electronic light bulbs have received FCC Part 18C certification for residential use. This means that they aren't going to interfere with radios or TVs. Most magnetic ballasts have never been tested by the FCC, they can be very noisy and interfere with radios and TVs. We have learned that coil capacitor ballasts produce much more heat than electronic ballasts. In fact, the manufacturers of compact fluorescent fixtures, that get them UL approved, must keep the internal temperatures of the fixtures below 120 øF. The entire industry is waiting for the low temperatures from electronic ballasts. They cost more, but have advantages. If we let the fixture manufacturers know that the trade off is worth it to them, they are with us. Conclusions: Compact fluorescent lighting systems are much more efficient than incandescent lighting. We see about four times the lumens per watt as compared to incandescent. There are more efficient systems than the compact fluorescent, but they usually aren't suitable for indoor use. Recently, fluorescent lighting has become much better at color rendition and can start almost as rapidly as incandescent lamps. With the emergence of electronic ballasts, heat dissipated in the ballast has been reduced and the performance of fluorescent lamp starting improved. Why bother? Energy savings!!! & $$$ Don't forget that your local power utility ( maybe even you! ) don't have to produce as much energy to feed your lighting needs. Ecological Benefits!!! CO2 from burning fossil fuels adds to "greenhouse effect" and global warming.. Acid rain kills trees and fish in lakes. Access: George Patterson, 3674 Greenhill Road, Santa Rosa, CA 95404. OSRAM Corporation, 110 Bracken Road, Montgomery, NY 12549-9700. ù 800-431-9980 or 914-457-4040