Download extending lifetime on t5 fluorescent lamp using an electronic ballast

Title:
EXTENDING LIFETIME ON T5 FLUORESCENT LAMP USING AN
ELECTRONIC BALLAST WITH FILAMENT PREHEATING
Authors:
Fernando Soares dos Reis, Member, IEEE
Reinaldo Tonkoski Jr. – Student Member, IEEE
Marcelo Toss
Anderson Soares dos Santos
Mailing address:
Pontifícia Universidade Católica do Rio Grande do Sul
FENG – DEE – LEPUC
Av. Ipiranga 6681, Prédio 30, Bloco E
CEP: 90470-000, Porto Alegre, RS - Brasil.
Phone: +55 (51) 3320-3540
Fax: +55 (81) 3320-3540
E-mail:
[email protected]
Contact author:
Fernando Soares dos Reis
Topic area:
Eletrônica de Potência e Acionamento de Máquinas
Abstract — In this paper is analyzed, simulated and tested
experimentally an electronic ballast for one lamp 28W/T5 with
voltage preheat. The lamp is driven by a LC series C parallel
resonant filter. During warm up the filaments are driven by
secondary winding of a LC series resonant filter, after preheat time
this circuit is cut off eliminating filament power. This work presents
rapid cycle test for determinate compatibility between fluorescent
lamp and ballast.
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EXTENDING LIFETIME ON T5 FLUORESCENT LAMP USING AN ELECTRONIC
BALLAST WITH FILAMENT PREHEATING
Abstract – In this paper is analyzed, simulated and tested experimentally an electronic ballast for one
lamp 28W/T5 with voltage preheat. The lamp is driven by a LC series C parallel resonant filter. During warm
up the filaments are driven by secondary winding of a LC series resonant filter, after preheat time this circuit
is cut off eliminating filament power. This work presents rapid cycle test for determinate compatibility
between fluorescent lamp and ballast.
I. INTRODUCTION
In the last years, it have had an evolution in use of the more efficient illuminating systems, certainly
motivated by increase of energy cost in the majority of countries. The investment necessary to generate and to
distribute electric energy is too large that governments adopt programs to promote use of the more efficient
equipment system. The conservation of electric energy has as main objective to improve the way to use the
energy, without losing the comfort and them advantages that it provides. It means to reduce the consumption,
reducing costs, without losing, at any moment, the efficiency and the quality of the services.
For the increase of the efficiency in lighting system some alterations are accomplished currently, as
example: to substitute fluorescent lamps by incandescent lamps, the use of electronic ballast in the place of
magnetic ballast, the use of the fixture and lamp more efficient. For more efficient fluorescent lamps, the latest
technologies have been incorporated add new substances in combination with new coating technologies.
Hanover Fair in 1995, great European manufacturers had presented the T5 a new fluorescent lamp with less
diameter, shorter, more efficient and developed for to be successor of T8 [1]. Nowadays, the T5 fluorescent
lamps are little used in Brazil, because it’s more expensive than T8 fluorescent lamps, however, as the T8/32W
fluorescent lamps are substituting the 40W/T12, in the future 28W/T5 will go to substitute the 32W/T8. The T5
fluorescent lamps had been developed especially to operate with electronic ballast and provide high efficiency
when fed in high frequency. As these lamps are more expensive than standard fluorescent lamps your life is very
important parameter in the project of the electronic ballast.
This work presents analysis, development of an electronic ballast with voltage preheat for one lamp
28W/T5 and rapid cycle test to determine the rated life of lamp with proposed electronic ballast.
II. RAPID CYCLE TEST FOR FLUORESCENT LAMP T5
To determining the rated life of fluorescent lamps, the Illuminating Engineering Society of North
America (IESNA) specifies a test method of operating a large sample of lamps on a 3 hours on and 20 minutes
off cycle and determining the median time until failure. This method may take up to 3 years to get results for a
specific lamp and ballast. Recently, rapid cycle methods intended to reduce the testing time have been published
[2].
Fluorescent lamp life is determined by the loss of the electron emitting coating on the electrodes. Some
of the coating is eroded from the electrodes each time the lamp is started, additional evaporation and erosion also
occurs during lamp operation. Electrode temperature directly affects the evaporation and erosion of the emitting
material, and so affects lamp life. Because electrode temperature is difficult to measure directly, electrode
resistance can be used as a related parameter. The method propose in this work to determining appropriate off
time for rapid cycle test for T5 fluorescent lamp is the same utilized in [2] for determinate off time for rapid
cycle test for T8 and compact fluorescent lamps. This method measure temporal changes in electrode resistance
after extinguish power in the lamp. The off time for rapid cycle test is determinate by how long takes electrode
temperature to stabilize.
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Measurement made in two lamps 28W/T5, for three major lamp manufactures, the results shows that,
almost all of the decrease resistance occurred after 5 minutes. This result demonstrates that, for any rapid cycle
tests, if the lamp off time is less than 5 minutes, the electrode has not cooled completely. This reduces the
damage to the electrode during lamp starting, and will likely result in overestimates of the number of cycles that
would occur before the end of life in application conditions [2]. The choosing of an appropriate on time is also
very important, some lamp manufacturers suggest that during rapid cycle testing 0.5 to 7 minutes on time should
be used to help “cure” the electrodes [3].
III. PROPOSED TOPOLOGY
Two fundamentally different drivers could be used for filament preheating: a current or a voltage source
[4]. An example of the current source approach is resonant filter LC series C parallel used in many commercial
electronic ballast, Figure 1 (a). In this case, the filaments placed inside LC tank resulting in excessive lamp
voltage during preheat an excessive filament current during running. The output stage has therefore been
modified for voltage source filament heating using secondary windings off of the resonant inductor, Figure 1 (b).
The result is a more flexible ballast output stage necessary for fulfilling the lamp requirements [4].
S1
S1
L2:3
Cs
DRIVE
LAMP
DRIVE
S2
L1
C1
VDC
L
C3
L2:1
C2
Cp
LAMP
VDC
S2
S3
(a)
(b)
L2:2
Figure 1. Electronic Ballast Topologies: a) Typical Ballast with Current Source Filament Preheat, a)
Topology Of Proposed Ballast with Voltage Source Filament Preheat.
IV. RESSONANT FILTER DESIGN
The proposed ballast is based on the multiresonant converter that consists in two resonant networks and
operates in two frequencies, preheat frequency and run frequency. Where the first one is higher than second one,
for keep low lamp voltage during preheat. The lamp is driven by a LC series C parallel resonant filter. During
warm up the filaments are driven by secondary winding of a LC series resonant filter, after preheat time this
circuit is cut off, by switch power S3, eliminating filament power.
The LCC filter design consists on choosing the correct phase angle () of LCC filter that concerns the
lamp starting and the correct lamp power in steady state. The LC series resonant filter is under study.
V. DESIGN PROCEDURE, SIMULATIONS AND EXPERIMENTAL RESULTS
Two prototypes of electronic ballast for a single T5/28W lamp will be projected, and simulated to verify
preheating efficiency, startup voltage and power lamp. The first one, will be without preheat control of the
filaments and the drive will have a resonant filter LC series C parallel with current fed filament, used in many
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commercial electronic ballast, show in Figure 1 (a). The second one, will control the preheat characteristics of
the filaments lamp using a second resonant network and will use as base first ballast for generated the voltage
startup and control the power lamp, after ignition. This ballast is show in Figure 1 (b).
VI. DISCUSSION AND CONCLUSION
The proposed multifrequency electronic ballast for fluorescent lamp T5 with voltage preheat will
provides a highly controlled warm up process. The filament are fed by a voltage source with tight tolerance
while the lamp voltage during the preheat period is very low, after this period the power filaments is cut off,
energy saving 1.5 to 2W per lamp. The two resonant networks could be considered independent, so the warm up
and steady state operation can be designed for optimum performance. Two different rapid cycle tests will be
made for tree electronic ballast in the follow conditions, show in Table 1.
Table 1. Comparative Experimental Results
Electronic Ballast Type
Multifrequency electronic ballast with voltage preheat
Electronic ballast without controlled preheat
Commercial electronic ballast, without controlled
preheat
Rapid Cycle Test – 30
seconds ON and 30
seconds OFF
Under test
Under test
1500 cycles
Rapid Cycle Test – 30
seconds ON and 5
minutes OFF
Under test
Under test
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The expected results of this work, after rapid cycle test around three mouth, is that the proposed
electronic ballast, multifrequency electronic ballast with voltage preheat, presents an lamp life more than the
others evaluated electronic ballast. Furthermore, expects that rapid cycle test with very short off-times (30
second ON and 30 second OFF) damage the lamp electrodes much less than cycles with longer off-times (30
second ON and 5 minutes).
VII. REFERENCES
[1] Gvén, T., “T5: economia de energia com novos materiais e projetos de luminárias”, Eletricidade Moderna
Magazine, Sept. 1998.
[2] Davis, R.; Yufen, J.; Weihong, C., “Rapid-cycle testing for fluorescent lamps: What do the results mean?”,
Annual Conference of the Illuminating Engineering Society of North America, 1996.
[3] “Startcoat T5- Product Information for Original Equipment Manufactures”, General Electric Company,
September 2001.
[4] Ben-Yaakov, S.; Shvartsas, M.; Ivensky, G., “HF Multiresonant Electronic Ballast for Fluorescent Lamps
with Constant Filament Preheat Voltage”, IEEE Transactions on Power Electronics, 2000.
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