Electrical ballast

As the required ballast for gas discharge lamps and fluorescent lamps for current limiting device is called.

• 3.1 Dimmable ECG
• 3.2 Aufsteck-EVG/T5-Adapter
• 3.3 electronic ballast for operation at low voltage
• 3.4 electronic ballast for fluorescent lamps
• 3.5 Operation of the TOE

Basics

A ballast is used for operating a gas discharge lamp. Otherwise, the discharge current would rise by the impact ionization required for their function and on until the lamp is destroyed or the fuse to blow.

It can be installed as a separate component in the light or in the bulbs be integrated ( as in so-called energy saving lamps). In this case, the lamp can be operated directly on the power grid.

Ballasts may also contain the necessary in some lamps ignition ( depending on lamp type pulses of a few hundred volts to several kV) and starting device ( preheating of the cathode fluorescent lamps ).

Ballasts (VG ) is available in two types:

• Magnetic ballasts
• Electronic ballasts

Magnetic ballasts

Magnetic ballasts need to operate a starter and after the losses divided into:

• Conventional ballast (CCG )
• Low loss ballast ( SG )

Conventional ballast (CCG )

So-called conventional ballasts consist of a throttle, usually a wound coils with copper wire iron core. Due to the ohmic resistance of the copper, ( the so-called copper losses) and the resetting and eddy current losses in the core leads to heat generation and power loss of about 10-20 % of the lamp power. The calculation of the inductive resistance is shown in this example.

The CCG is connected in series with the lamp and the lamp must fit, as it limits the current of the lamp to its nominal value at the line frequency of 50 or 60 Hz. For lamps requiring an igniter ( as sodium vapor lamps and metal halide lamps ), the ignition circuit is also in series with the lamp.

KVG for fluorescent lamps also need a so-called starter which switches the hot cathode at startup for preheating directly into the circuit (see under fluorescent lamp). Glow starter cause the characteristic flickering of fluorescent lamps at the start, quick starter does not have this disadvantage.

Conventional ballasts cause due to their inductance reactive current in the network. In some cases lamps are therefore fitted with a reactive current compensating capacitor ( power factor correction ). The capacitor when it is connected in parallel with the lamp not required for the function. Partial compensation switched capacitors are used in series with the inductor to reduce the inductive load when switching on ( see inrush current). Their capacitance value must be close tolerances to ensure the rated current of the lamp. If they fail by shorting out the light without disturbance to work, but it is now no longer blind current-compensated.

CCG are extremely reliable, they can operate without problems for decades and need not be replaced.

The sale of CCG with the energy efficiency class D is banned in the EU since 21 May 2002, which. Devices from Class C since November 21, 2005

Low loss ballast ( SG )

The so-called low-loss ballasts are a further development of the CCG. The SG are characterized by a lower power loss. However, they have not achieved any great importance, because they partly larger dimensions than the conventional ballasts have and due to the use of larger iron packages and better alloys in the production are material- consuming. The losses can be reduced by a larger coil cross section and higher quality core materials or by lower magnetic flux densities.

New on the market are magnetic ballasts with smaller than in the class A2 specified losses. These ballasts are also available for T5 bulbs, environmentally friendly easy to recycle in the production and because of the small range of materials.

KVG for fluorescent lamps

Conventional ballasts for fluorescent lamps and cold cathode tubes are reactance transformers and combine the transformation of the mains voltage into a high voltage ( several kilovolts ) and their current limitation. They often have a setting for the current in the form of a mechanical variable magnetic shunt.

Electronic ballast ( EVG)

In addition to CCG, there are also electronic ballasts (EVG). A distinction between cold-start ballast and hot restart ECGs, being additionally distinguished in the hot restart ECGs between single- and double-sided hot restart ECGs.

Cold start ballasts ignite the fluorescent lamp after switching to a high voltage. They claim the lamp cathodes during starting strongly and thereby reduce lamp life considerably. In most cases, cold-start electronic ballasts are used in low lighting.

With hot restart ECGs, the hot cathode fluorescent lamp are preheated and this ignited only after a period of about 0.5-2 seconds. The start and ignition of ballast carried flicker in contrast to conventional control gear (CCG ) with a conventional starter. The boot process is thus usually noticeably faster than CCG.

ECG operate the gas discharge lamp at a higher frequency, typically for fluorescent lamps 32 to 40 kHz. They are smaller and lighter, have lower losses than CCG, a better power factor ( 0.97 to 0.99 ), the lamp reaches them more efficient and does not flicker. There are also electronic ballasts that can provide instead of two fluorescent lamps, if they are in a luminaire. Advantages of electronic ballasts are a better light quality ( Flackerfreiheit ) at lower intrinsic losses compared with CCG and thus a lower power consumption simultaneously. Due ballast circuit can also be supplied dimmable, whereby about tageslichabhängige arrangements are possible.

An important characteristic of most ECG, the almost harmonics and reactive current free load characteristics on the network. Fixed TOE have usually by a power factor correction has a power factor close to unity and therefore require no power factor correction

However, in energy-saving lamps electronic ballast must due to the low performance so far have no power factor correction.

Dimmable electronic ballast

Dimmable electronic ballast is available in two versions:

• Analogue dimmable electronic ballast
• Digital dimmable electronic ballast

Be driven by a control signal from 1-10 volts analog dimmable ballast. The ECG is separated network when switched off the light and thus has no standby losses.

Digital dimmable electronic ballasts can be controlled by a DALI bus signal. The system allows to operate up to 64 lights on a bus segment. States can be reported back. The TOE is also in the off state of the light always on network and thus has stand-by losses.

In both variants, the control line can be carried in addition to the supply line. Due to the reactive power control of lumen depreciation is always greater than the current decline.

Aufsteck-EVG/T5-Adapter

For upgrades are available from various vendors plug- ECG offered where existing lights already be used. The ECG is thereby inserted between the old version and a conventional bulbs smaller design. With this plug- ballast however occur by design considerable problems ( life of the ballast, correct operation of the lamp, electromagnetic compatibility, missing Certifications and approvals ), so that this solution can not penetrate the market. This mainly concerns the operation of T8 lamps with electronic ballasts. Since 2004, individual providers have indeed all the necessary Certifications and approvals, however, these ECG intervention in the design of the lamp is and their marks and approvals expire. Likewise fail most manufacturers warranty and product liability. After the upgrade, the manufacturer of the TOE is considered luminaire manufacturers and must handle warranty claims and product liability of the lamp. Since providers repeatedly made ​​false statements, you should make sure to test certificates by TUV, VDE and Federal Institute for Occupational Safety and Health.

Another variant of the conversion are adapters to operate T5 lamps in T8 lamp holders. Benefits are savings without changing the luminaire housing, ie low conversion costs. There arise indeed advantages of the T5 lamp generation in the old luminaire housings, but photometric properties of the lights are achieved only partially. A disadvantage can be a low power light and fire hazard by heating the adapter during operation. Also the power factor λ of the total light is changing in this conversion due to the lower performance of a T5 lamp. The lamp contained in the CCG or SG is used only as a line filter, they remain in this.

The life of the changeover ECG is around 15 years. The T5 lamps offer each reputable provider, the service life is around 16000-30000 hours, instead of 6,000-8,000 hours for T8 lamps in light color 840

Note: For safety and EMC reasons, the use of T5 adapters in T8 lights is to be regarded as very questionable. The electrical problems is the fact that some adapters systems, the allowable T8 Lamp total weight does not take into account (eg CB Scheme). Complete lighting that drive on both sides with the help of ballast T5 lamps can be used without hesitation for a given electromagnetic compatibility in order to take advantage of the T5 lamp. Manufacturer of lamps and lighting do not recommend the use of adapters in lights. Measurements in Switzerland demonstrate any usefulness for T5 adapter.

Electronic ballast for operation at low voltage

There are also electronic ballasts for use with low-voltage DC voltage ( 12 or 24 volts). These can be operated on a battery, which makes them suitable for use with solar power systems, in vehicles, or on boats in the small garden.

Often such lamps as well as line voltage energy saving lamps are equipped with an E27 screw, thus there is a high likelihood of confusion.

Electronic ballast for fluorescent lamps

Ballasts for cold cathode fluorescent lamps (CCFL, backlight of LCD and fluorescent lamps for advertising) are often referred to as an inverter; they generate from the battery or mains voltage a current limited high voltage ( 500 V to several kV) high frequency and do not require preheating.

ECGs for cold cathode tubes often have an electronic or mechanical ( Potentiometer ) dimming.

In light advertising several fluorescent lamps are often operated in series to a ballast or power supply unit. Their maximum AC voltage is limited by VDE regulations to 7.5 kV.

Operation of the TOE

The high inrush current can be solved within a circuit depending on the design by limiting the number of ECGs. The reliability is not achieved by the electronic components coming to use the values ​​of a CCG.

Critical is the operation of multiple ECGs with a GFCI, since ECG derive a reactive current through the protective conductor because they contain mains filter. The leakage current must indeed be less than 0.5 mA, but when turned on it is higher. Therefore, care should be taken when reinstalling with GFCI that this pulse current is fixed or delayed triggers. As a planning value only half the trip current of the RCD should be set for safe operation: with a RCD with a tripping current of 30 mA half the tripping current is 15 mA;

The cost-effectiveness of ECG depends strongly on the annual burning hours, this should not be less than 1,500 hours.

ECGs are sensitive to neutral fraction, the resulting higher phase voltage they can not cope.

ECGs due to the built-in electronics components, a shorter service life than magnetic ballasts, one expects 50,000 hours (approx. 6 years non-stop nominal lifetime ), which is reflected in its amortization.