What might happen when the lamps gets defect?
BAG electronics ECG feature automatic recognition and safety switch-off in case of abnormal lamp operation. This includes e.g. efectivelamp electrodes or highly resistive discharging distances caused by leaky tubes.As well, the critical operating condition at the end of service life of fluorescent lamps is detected. The at that time arising rectifier effectleads to increased lamp burning voltage in the surroundings of the electrodes and thus to raised temperature in that area. This process results from the loss of emitter material arising in the course of operating time. Particular importance inheres in this so called End-of-Life phenomenon when T5 lamps are considered. Due to the decreased tube diameter being 16 mm, the raise in temperatureis more significant than in case of T8 lamps with a diameter of 26 mm.As a consequence of the possible endangerments caused by thermal overload, the safety regulation EN 61347-2-3 for electronic control gear units includes the examination of a functional End-of-Life switch-off. There are three test methods available which of especially for T5 lamps the procedure “Test 2” is known to be particularly reliable.ECG from BAG electronics, marked are tested and approved according to the criteriarequired there.
Do electronic ballast extend the lamp service life?
In respect of the service life of fluorescent lamps, the number of switch-on/switch-off cycles per day and the mode of the starting procedure are of significant importance. An optimised start requires appropriate preheating of the lamp electrodes. Electronic control gear units of premium quality, feature warm start procedures which lead substantially to an increase of lamp service life of up to 50 % in comparison to an operation with inductive ballasts. A lamp service life virtually independent of the switching frequency can be achieved by means of a preheating which is exactly adjusted to the lamp. BAG electronics ECGs, e.g. of the series D and SCS, meet this requirement via digitally controlled starting procedures. Preheating is provided by an approximately constant current within a predefined period. An incidental ignition of the lamp, ahead of time, is excluded by the circuit design. Measurements in our laboratories have shown that more than 1,000,000 switching cycles at 15 seconds intervals were not able to destroy the electrodes.
A technologic innovation for further optimisation of the lamp start is given by energy controlled preheating. Corresponding requirements are already constituted in regulation EN 60929 regarding performance of electronic control gear units, in fact in a first step for T5 fluorescent lamps. The advantage of this procedure is that during the starting phase not only the preheating current but the energy being fed to the electrode is considered. This allows a straight statement with regard to the point in time where the optimum emission temperature has been reached. The preheating phase is then automatically terminated. As a result, the influence of tolerances, such as of the lamp electrodes, is being reduced and thus even sensible electrodes are prevented from unnecessary loads. All marked electronic control gear units from BAG electronics for T5 lamps are already offering the optimised procedure of energy controlled preheating.
How long is the service life of an electronic ballast?
Service life and thus the reliability of electronic control gear units is determined by the failure rate of their fitted components. Along with the electrical specification and the quality of these components, the temperature is an essential parameter. BAG electronics ECGs are designed so that a failure rate of maximum 2 ‰ per 1,000 hours may be expected if the maximum admissible housing temperature tc,max which is indicated on the ECG is respected. This represents a service life of 50,000 hours at a possible failure rate of < 10 %. In other terms this means that at an annual rate of 2,500 operating hours a service life of 20 years will be achieved at a possible statistical failure rate of 10 %. Lower temperatures within the electronic control gear units extend their service life. If for instance the temperature tc, max is 10 °C lower, the failure rate is approximately halved. Analogically, in case the temperature tc, max. is exceeded this may lead to a drastic reduction in the service life.
As a measure to secure the specified service life all components and circuits of ECGs from BAG electronics are designed to be operated below their admissible limiting values. Moreover, in order to prevent early failures caused by covert defects, all units pass various testing points during the manufacturing process, i.e. amongst other things component checks as well as measurements of operation-relevant data are made. Before they are delivered ECGs are subject to a final burn-in-test.
What the advantage of electronic ballasts in comparison to inductive ballasts?
The ignition and the current limitation of the gas discharge in a fluorescent lamp require a control unit connected in series. Conventional technique use an iron core wound with copper wire in combination with a separate starter.
Essential advantages are offered when using electronic control gear units:
• Cost and energy savings
• Increased lighting comfort thanks to flickerfree lamp start and calm light
• Increased lamp service life and extended maintenance intervals
• Safety switch-off in case of critical operating conditions
A basic distinctive feature between inductive ballasts and electronic control gear units (ECG) is given by the mode of lamp operation. Electronic control gear units generate high-frequency alternating voltages with frequencies of about 30 to 70 kHz. As a result, the luminous efficacy of fluorescent lamps is increased by approx. 10 % versus the 50/60 Hz operation of inductive ballasts. Thus, the high-frequency operation allows to lower the system rating without reducing the luminous flux of the lamp. The physical reason can be seen from the course of the lamp voltage. When operated at mains frequency, the lamp is shortly extinguished after each mains half-wave and has to be re-ignited what results in the shown voltage peaks. The dark phases lead on an average to reduced luminous flux and the so-called 100 Hz flickering.
What does the energy-efficiency-index (EEI) stand for?
The Energy-Efficiency-Index serves as a basis for an objective evaluation of the efficiency of a ballast-lamp-system. This parameter has been introduced by CELMA, the Federation of National Manufacturers Associations for Luminaires and Electrotechnical Components for Luminaires in the European Union. Per lamp type 7 categories with different limiting values for the total input power are defined. In order to assure a standardised classification of a given control unit into the Energy-Efficiency-Index, measurements are based on the European Norm EN 50 294 “Measurement method of total input power of ballast-lamp circuits”.
The Energy-Efficiency-Index especially applies via the implementation of the European Regulation 2000/55/EC about energy efficiency requirements as to ballasts for fluorescent lamps. This regulation aims at provoking the changeover to efficient and energy saving systems in view to improved climate protection. Against this background, according to EC-Regulation, inductive ballasts with very high power loss, classified D, are since 21.05.02 no longer allowed to be circulated. This applies from 21.11.2005 on as well for inductive ballasts classified C.
Further information concerning this classification with limiting values for all common lamp types can be found in CELMA brochure called ”Guide for the application of Directive 2000/55/EC on energy efficiency requirements for ballasts for fluorescent lighting”.
How much energy savings can be achieved?
In order to compare the power consumption and the efficiency of fluorescent lamp circuits, the system consisting of lamp + ballast has to be regarded in consideration of the achieved luminous flux of the lamp. For example, a fluorescent lamp rated as 58 W, requires system power of up to approx. 71 W when it is operated via a conventional inductive ballast. When using electronic control gear units the system rating amounts to only 55 W. Based on similar lighting levels, a lighting installation with conventional inductive ballasts therefore requires at least 30 % more energy than an identical lighting installation fitted with ECGs. Energy savings result as well from the reduced lamp power as from the significantly lower power loss of an electronic control gear.