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1、LSD 5-2009 A NEMA Lighting Systems Division Document 34-Watt Fluorescent Lamps and High Frequency Electronic Ballast Compatibility Prepared by the Lamp Section National Electrical Manufacturers Association 1300 North 17th Street, Suite 1752 Rosslyn, Virginia 22209 Date: 22 January 2009 The requireme
2、nts or guidelines presented in this document, a NEMA Lighting Systems Division white paper, are considered technically sound at the time they are approved for publication. They are not a substitute for a product sellers or users own judgment with respect to the particular product discussed, and NEMA
3、 does not undertake to guarantee the performance of any individual manufacturers products by virtue of this document or guide. Thus, NEMA expressly disclaims any responsibility for damages arising from the use, application, or reliance by others on the information contained in these white papers, st
4、andards, or guidelines. 1 LSD 5-2009 34-Watt Fluorescent Lamps and High Frequency Electronic Ballast Compatibility Introduction Prior to the energy crisis of 1974, fluorescent lamp-ballast combinations were fewer. Potential interaction and interoperability of lamps and ballasts was a much simpler to
5、pic. Forty-watt four- foot (F40) T-12 rapid-start lamps operated on 60 Hz rapid-start electromagnetic (EM) ballasts. This typical de-facto system represented the vast majority of mainstream indoor commercial lighting installations for offices, schools, institutions in general, and retail establishme
6、nts.1 Electromagnetic ballast designs had already fully matured by the early 1970s. As a result, the ballast designs tended to exhibit relatively minor differences among manufacturers, particularly in terms of electrical circuit configurations and typical components. Electromagnetic ballasts started
7、 and operated F40 lamps in essentially the same manner. Similarly, F40 rapid-start lamps were of simpler construction in comparison to the energy saving types that would follow. Argon was the fill gas of choice at a pressure of approximately 2.4 torr. Internal lamp conductive coatings had not yet be
8、en introduced, and phosphor coatings consisted of simple halo phosphate materials. Cool white was the most prolific lamp color. High frequency2 operation of fluorescent lamps had been introduced, but on a very limited scale. The costs of such ballasts (compared to EM ballasts) as well as the relativ
9、ely low electrical energy rates offered little incentive to develop or purchase such advanced systems. 1974The Energy Crisis The first Energy Crisis occurred precipitously in 1974. As a result, commercial lighting users, looking for quick ways to reduce their soaring electrical energy costs, experim
10、ented with a variety of approaches, and especially targeted the large installed base of F40 fluorescent luminaires. Many users soon began removing two of the four lamps from then common four- lamp, two-EM ballast luminaires of the day. However, it was soon recognized that this practice resulted in s
11、everal major deficiencies: - Removal of two of the four lamps resulted in a drastic reduction in light level (50%) - The de-lamped luminaire had a poor aesthetic appearance (dark spaces) - The un-lamped ballast continued to dissipate significant energy even though its lamps had been removed from the
12、 luminaire, and the ballast remained in a constant starting mode which hastened its failure Thus, de-lamping was not considered an acceptable long-term solution. As a result, lamp manufacturers began considering ways to design a new lamp that could be retrofitted into the same luminaire but that wou
13、ld operate at significantly reduced wattage (on the existing EM 60 1 This paper will concentrate on commercial as opposed to residential compatibility. 2 Meaning high in comparison to the 60 Hz line frequency, typically any frequency above 20 KHz, to avoid audible sensation. 2 LSD 5-2009 Hz ballasts
14、) while maintaining a full complement of operating (illuminated) lamps in the luminaire and delivering acceptable light levels. Energy Saving Fluorescent Lamp The answer to this dilemma was the first generation of energy saving fluorescent lamps. While all fluorescent lamps are by their nature energ
15、y saving compared to other lighting alternatives, the misnomer stuck. The term energy saving became the generic term applied to a new class of fluorescent lamps that were designed to be compatible with existing luminaires, operate on installed 60 Hz EM ballasts, and consume fewer watts when retrofit
16、ted into such existing systems. An energy saving fluorescent lamp was created by changing the lamp fill gas from argon to predominantly krypton, which reduced the lamp operating voltage by approximately 15%. Since EM ballasts operate fluorescent lamps in a constant current mode, this resulted in a c
17、omparable reduction in system wattage. The new four-foot energy saving lamps operated at a nominal 34 watts as opposed to the nominal 40 watts of the full-wattage argon filled lamps. The energy saving lamps would permit users to discontinue de-lamping and yet still save significant energy costs. A m
18、oderate light loss was acceptable, and the aesthetic appearance of a uniformly lit ceiling was restored. However, changing the lamp fill gas to krypton required greater ignition voltages to reliably initiate the lamp electrical discharge (or start the lamp). The starting voltage required for krypton
19、, especially at low line voltage or lower ambient temperatures, was found to be beyond the capability of the existing installed EM ballasts. After much experimentation, innovation, and the development of new lamp manufacturing processes, lamp manufacturers discovered that deposition of a thin conduc
20、tive coating on the inside of the lamp wall had the same effect as moving the luminaire ground plane closer to the lamp. The internal starting aid formed by this tin conductive coating permitted the available starting voltage from existing EM ballasts to initiate reliable starting of the new class o
21、f energy saving lamps. From this point the tin-coated energy saving four-foot fluorescent lamp became a mainstay of the fluorescent lamp family, at one time reaching a 50% penetration. While simple in principle, the deposition of the conductive coating requires a very complex manufacturing process a
22、nd tight control of the tin deposition process to ensure reliable 60 Hz starting. Thus the conductive coating process was optimized for 60 Hz ballasts and is largely unchanged to this day. Operation of F34 Energy Saving Lamps on High Frequency Ballasts Commercial electronic ballasts operating at abo
23、ve 20 kHz became common in the late 1980s. Since at that time, the majority of four-foot lamps sold were still T12 and not T8, most electronic ballasts operated T12 lamps. In an attempt to maximize energy savings, some electronic ballasts were paired with energy saving F34 lamps, even though the maj
24、or energy saving from 3 ? LSD 5-2009 an electronic system was realized from a lower operating current and reduced lamp losses that result from operation at higher frequencies. While in many cases, such systems performed acceptably, it was discovered that in a significant number of cases, operating e
25、nergy saving F34 lamps on high frequency electronic ballasts resulted in lamp starting issues in the field. This was due to the fact that the internal conductive coating of the lamp, which is an aid for 60 Hz starting, can actually work to reduce the reliability of high frequency starting in some si
26、tuations. While the detailed complexities of this potential interaction are beyond the scope of this paper, there are two basic mechanisms that were found to impair the starting of F34 energy saving lamps3 on high frequency electronic ballasts: - The internal lamp conductive coating acts to provide
27、a capacitive leakage current path to ground that is more significant than the 60 Hz leakage path. In some cases, this may impede lamp starting, especially where starting conditions may have already been less than acceptable initially. This type of situation would typically be experienced when system
28、s were first commissioned, i.e., EM ballasts that had been operating F34 energy saving lamps were replaced with electronic high frequency ballasts. - The internal lamp conductive coating materials interact in a complex manner with other internal lamp materials to develop poor starting later in lamp
29、life. This situation, which is not immediately obvious, resulted in some cases when a lamp darkened at its ends. In such a case, the resistive profile of the internal conductive coating changed such that the arc would hang up upon starting and complete lamp starting did not occur. In such cases, the
30、 interaction was developmental, meaning it did not occur immediately but only later as the lamp aged. In such cases, end users mistakenly concluded the lamp had prematurely reached end of life when in reality it lost its ability to start under high frequency operation. Such lamps subsequently would
31、start if they were operated on 60 Hz EM ballasts. As a result, lamp manufacturers did not recommend the operation of F34 lamps on high frequency electronic ballasts, especially with the advent of high efficiency T8 systems that were also being used increasingly in retrofit situations. Todays Situati
32、on: T12 and T8 System Trends Today, the lamp market has continued to dramatically shift to T8 lamps4 and electronic ballasts to maximize energy savings. The use of F34 T12 energy saving lamps has declined and will continue to decline, whether such lamps are used on EM or electronic ballasts. NEMA es
33、timates that in 2007, a total of 330 million four-foot fluorescent lamps were sold domestically, of which approximately 70 million were F40 T12, 60 million were F34T12, and 200 million were F32 T8 types. The trend to T8 lamps will continue with T12 lamps becoming a smaller and smaller portion of the
34、 commercial market (and, eventually, the residential market). 3 Eight-foot energy saving lamps, although they employ krypton fill gas, do not employ an internal conductive coating. As a result, these lamps do not have similar potential interaction effect with high frequency electronic ballasts. 4 An
35、d, increasingly, T5 lamps. 4 ? LSD 5-2009 Todays Situation: Operation of F34 Energy Saving Lamps on HF Electronic Ballasts Electronic ballasts have evolved considerably since they were first introduced, even since the F34 was the predominant energy saving lamp type. Electronic ballast designs that a
36、re currently offered for use on F34 energy saving lamps have sufficient starting capability that minimizes the possibility of the types of starting issues described earlier in this paper. While it is still possible that such interactions might occur under certain conditions, there are currently no i
37、ndustry reports of electronic ballast-F34 lamp starting reliability field issues among NEMA member lamp and ballast manufacturers. NEMA Recommendation: High Frequency Lamp & Ballast Options The most common four-foot fluorescent lamp family today for achieving maximum energy savings on electronic bal
38、lasts is the F32T8 series (which includes lower than 32-watt versions as well). This trend (and, increasingly, a future trend to T5 lamps) will continue to accelerate, both as a result of specifier and end user demand and because ongoing legislative efforts by the U.S. Department of Energy will cont
39、inue to drive future energy saving fluorescent offerings towards T8s, T5s, and electronic ballasts. The use of T12 F34 lamps, especially on electronic ballasts, will continue to strongly decline, particularly since it is expected that new U.S. DOE lamp efficiency requirements will eliminate these la
40、mps effective 2012. NEMA members recommend that commercial users seeking to upgrade four-foot lighting systems should preferentially specify T8 or T5 lamps and high efficiency electronic ballasts. In the event that an end user chooses to use modern era T12 electronic ballasts in conjunction with F34 lamps, it is likely that the combination will prove reliable and compatible, especially where lamp manufacturers indicate that high frequency ballasts are among the recommended ballast choices for F34 lamp operation. 5