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THE INFLUENCE OF PROGRAMMED START BALLAST IN T5
FLUORESCENT LAMP LIFETIME A INFLUÊNCIA DO
REATOR COM PARTIDA PROGRAMADA NA VIDA ÚTIL DA
LÂMPADA FLUORESCENTE T5
Authors Anderson Soares Fernado S. dos Reis
Marcelo Toss Reinaldo Tonkoski
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• THE INFLUENCE OF PROGRAMMED START BALLAST
• IN T5 FLUORESCENT LAMP LIFETIME
• Introduction
• T5 fluorescent lamps, characteristics
• Proposed topology
• Simulation results
• Experimental results
• Rapid cycle test for T5 fluorescent lamps
• Discussion
• Conclusion
• References

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• INTRODUCTION
• In the last years, it have had an evolution in
  use of the more efficient illuminating systems,
  as example to substitute fluorescent lamps by
  incandescent lamps, the use of electronic ballast
  in place of magnetic ballast, the use of more
  efficient fixtures and lamps.
• 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 Gvén.
• This work presents analysis, development of an
  electronic ballast with voltage preheating for
  one 28W/T5 fluorescent lamp and rapid cycle test
  to determine the rated lifetime of lamp with the
  proposed electronic ballast.

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1. INTRODUCTION

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• T5 FLUORESCENT LAMPS Characteristics
• Less diameter 16mm (T5) to 26mm (T8), 40
• Less lengths 1149mm (28W) to 1200mm (32W)
• Lamp efficacy up to 104 lm/W
• (10 compared T8)
• Maximum light output at 35C (25C T8)
• Low mercury dose
• Constant lumen level during lamp life (92 at
  10.000 hours)
• High frequency operation (no flicker)
• More expensive (approximately 2.5 x T8)

Fig. 01 Fluorescent lamps, evolution.
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• T5 FLUORESCENT LAMPS Characteristics
• For a long lifetime and a stable light output,
  the electronic ballast should fulfill the strict
  requirements for preheating and steady state
  operation, as following Davis
• Preheating Operation
• The filament should be first heated to an
  optimum temperature (about 1000K).
• During filament preheating, the voltage across
  the lamp should be kept as low as possible.
• Only after the filaments optimum temperature is
  reached, the voltage of the lamp should rise to
  the ignition level.
• Steady State Operation
• Once the lamp is ignited, the ballast should
  behave as a current source to ensure stable
  operation.
• The crest factor of the lamps current should not
  exceed 1.7.

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1. PROPOSED TOPOLOGY

• Selection of a preheating method depends on the
  types of filaments and on time available for
  ignition lamps Chin. Two fundamentally
  different drivers could be used for filament
  preheating DavisChin a current source or a
  voltage source.
• Current Source Filament Preheating

• Disadvantages
• The filaments are placed inside the LC resonant
  filter, resulting in excessive lamp voltage
  during preheating and excessive filament current
  during runtime Davis.
• After lamp ignition, the filament power consumes
  about 0,5W for each filament.
• Advantages
• Simple configuration
• High Efficiency.

Fig. 02 Circuit diagram of a conventional
series-resonant parallel load electronic ballast.
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1. PROPOSED TOPOLOGY

The drive works in two different frequencies (fPH
and fRUN). During preheating operation, the
secondary windings (L22 L23) supply the
filaments and the LC series C parallel filter
keeps the low voltage across the lamp. After this
period the frequency changes to the RUN frequency
and a high voltage is applied to capacitor C2
providing the necessary voltage for lamp ignition.
Fig. 05 Warm up, start up and steady state
frequency range.
Fig. 04 Topology of proposed ballast.
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1. PROPOSED TOPOLOGY

• Voltage Source Filament Preheating
• An alternative approach for eliminate the
  disadvantage of this topology, presents an
  alternative method to achieve a voltage filament
  preheating.

• Advantages
• The two resonant filters provide sufficient
  decoupling between the preheating and the steady
  state operation, so that each may be designed for
  optimum performance.
• The lamp may be started up without the adverse
  effects on the lamp lifetime.
• The filaments power is eliminated after the
  preheating time, increasing system efficiency.

Fig. 03 Topology of proposed ballast based on a
voltage source filament.
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• SIMULATION RESULTS (ORCAD/PSPICE)
• Some simulations were carried out in order to
  verify the behavior of the proposed ballast under
  preheating, startup and steady state operation.

Fig. 06 Simulation circuit, Orcad Software.
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1. SIMULATION RESULTS

Preheating Startup
Steady state
Filament Voltage VRMS 7,6V
Ignition lamp voltage VPICO 1800V
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1. EXPERIMENTAL RESULTS

Preheating Frequency
Run Frequency
( 06 )
( 07 )
Fig. 08 Prototype circuit of the proposed
electronic ballast.
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1. EXPERIMENTAL RESULTS

Fig. 09 Prototype board of the proposed
electronic ballast.
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1. EXPERIMENTAL RESULTS

Filament (CH2) and lamp Voltage (CH1)
Measured Lamp voltage during start up VLAMP
2,04 kVPeak Specified Minimum lamp voltage
VLAMP 750VPeak
Preheating time 2s
Measured Lamp voltage VLAMP 55VRMS Specified
Maximum lamp voltage 240VRMS
Measured Filament voltage VRF
7,5VRMS Specified Minimum 6,0V e Maximum
7,9VRMS
Zoom Preheating
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1. EXPERIMENTAL RESULTS

Lamp voltage vs. lamp current
ILAMP 0,175A (nominal value ILAMP
0,170A) VLAMP 178V (nominal value VLAMP 167V)
Table I
Electrical measurements 28W/T5 with Power
Analysis System Xitron 2572R .
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1. RAPID CYCLE TEST FOR T5 FLUORESCENT LAMPS

To determinate the rated average lifetime of
fluorescent lamps, the Illuminating Engineering
Society of North America (IESNA) specifies a test
method using a large sample of lamps. This
method consists of burning cycles, at which the
lamps remain ON during 3 hours and OFF during 20
minutes. This method may take up to 3 years to
get results for a specific lamp and ballast.
Recently, rapid cycle methods, intended to
reduce this testing time have been published
Ben-Yaakov.
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1. RAPID CYCLE TEST FOR T5 FLUORESCENT LAMPS

Fluorescent lamp lifetime is determined by the
loss of the electron-emitting coating on the
electrodes. Electrode temperature directly
affects the evaporation and erosion of the
emitting material, therefore affecting the lamp
lifetime. Since electrode temperature is hard to
measure directly, electrode resistance may be
used as a related parameter Chin. A method
proposed by Davis establishes the OFF time for
rapid cycle test for T8 and compact fluorescent
lamps, based in the measurement of the electrode
resistance change after power extinguishes in the
lamp. The same analysis will be applied in
this work to define the appropriate OFF time for
rapid cycle test for T5 fluorescent lamp.
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1. RAPID CYCLE TEST FOR T5 FLUORESCENT LAMPS

From three of the major lamp manufacturers, two
28W/T5 fluorescent lamps were randomly selected
and measured from each manufacturer. The results
obtained for the three lamp companies were
basically the same.
Fig. 12 A Manufacturer lamp resistance ()
versus time (min).
These results demonstrate that, for any rapid
test cycles, if the lamp OFF time is less than 5
minutes, the electrode does not cool completely.
This reduces the damage to the electrode during
lamp starting, and will probably result in
overestimation of the rated average lifetime
Ben-Yaakov.
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1. DISCUSSION

• To verify the compatibility between proposed
  electronic ballast and T5 lamp, two cycle tests
  were made with three different ballasts
• Cycle tests
• Cycle time used by Brazilians ballast
  manufacturer (30s ON and 30s OFF)
• Cycle time found on the cooled filament (30s ON
  and 5min OFF)
• Electronic ballasts
• Electronic ballast with voltage preheat, as
  proposed
• Electronic ballast without preheating
• Commercial electronic ballast found in Brazilian
  market, without preheating.

Table II
40580
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1. DISCUSSION

• The first rapid cycle test was conclude after 40
  days. The rapid cycle test used by ballast
  manufacturer determines a minimum number of
  cycles until the lamp failure.
• As an example, in the most common commercial
  application the lamp is turned ON and OFF two
  times in 12 hours, so the minimum expected number
  of cycle within this period is 6700. Therefore,
  only the electronic ballast proposed should be
  approved.
• The second rapid cycle test was concluded after
  155 days. The lamp manufacturer specifies a
  lifetime 20000 cycles to rapid cycle test with
  30s ON and 4.5 min. OFF. In this situation, only
  the electronic ballast proposed should be
  approved.

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1. CONCLUSION

• The proposed multifrequency electronic ballast
  topology provides a highly controlled preheating
  process. The filaments are fed by a voltage
  source with tight tolerance, while the lamp
  voltage during the preheating period is very low.
  
• The circuit was analyzed, simulated and
  experimentally tested, and the results support
  the validity of the model developed in this
  paper.
• The filaments power is eliminated after the
  preheating time, increasing system efficiency.
• The rapid cycle test point out the importance of
  the preheating circuit in the T5 lamp lifetime.
  Therefore, the electronic ballast proposed is an
  excellent choice for T5 fluorescent lamps.

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1. CONCLUSION

• In November 2004 was published at DIÁRIO DA
  UNIÃO, number 217, part 188, references to
  Brazilian electronic ballast standards NBR14417
  and NBR14418, specifies to T5 fluorescent lamp.
• Electronic ballast for T5 fluorescent lamp
  without preheating, instant start type, cant be
  manufacture, import or market.

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1. REFERENCES

1 Ultra-Slim Design With Extraordinary Light
Output, SILHOUETTE T5, Philips Lighting Company,
September 2001. 2 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. 3 T.-F. Wu C.-C.
Chen J.-N. Wu, An Electronic Ballast with
Inductively Coupled Preheating Circuits, IEEE
Transactions on Power Electronics, 2001. 4 Chin
S. Moo Tsai F. Lin Hung L. Cheng Ming J.
Soong, Electronic Ballast for Programmed
Rapid-Start Fluorescent Lamps, IEEE Transactions
on Power Electronics, 2001. 5 Do Prado, N. R.
Seidel, R.A. Bisogno, E. F. Costa, D. A. M.,
Self-Oscillating Electronic Ballast Design, IV
Conferência de Aplicações Industriais
Induscon2000, Porto Alegre, Rio Grande do Sul,
Novembro 2000. 6 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. 7 Klien D., A New Concept for
Fluorescent Lamp Ballasts, IEEE Transactions on
Power Electronics, 2000.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO
SUL