D7BCT datasheet(26/54 Pages) OSRAM

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2. Function and technical design

OSRAM DULUX® EL – electronic energy saving lamps

Economical alternatives to ordinary light bulbs

Technical Guide

2.2

Electronic

control gear

2.2.1 Operation

Fluorescent lamps need a voltage pulse of several hundred volts in order to start, and

need the current to be limited to several hundred mA in order to continue operating

properly. In conventional control gear (CCG operation), these two functions are

provided by an inductive resistor (choke) and starter. Chokes for a mains frequency

of 50 Hz are large and heavy and cause power losses that in the case of compact

lamps may be as much as 40 % of the total power input.

Instead of conventional control gear, an OSRAM DULUX® EL lamp has integrated

electronic control gear for starting and current limitation. The electronic circuitry is

small and lightweight. The lamp starts quickly and without flickering.

The power losses are only one third of those of conventional control gear.

Electronic control gear contains a number of functional elements:

Fig. 3: Block diagram of electronic control gear

First, a DC voltage of about 280 V is produced from the 50 Hz mains voltage by a

rectifier with a smoothing capacitor. This voltage is converted into a square-wave

AC voltage with a frequency of more than 40 kHz in the high frequency generator

(oscillator), in which two transistors operate as fast acting switches. Even if electronic

control gear is used, current limitation and power setting are still handled by chokes.

Because of the high operating frequency, however, they have a very much smaller

inductance (owing to impedance Z = H x

ω) and smaller dimensions than the ones

used with conventional control gear.

For the lamp to start properly, a voltage of several hundred volts must be applied.

In OSRAM DULUX® EL LONGLIFE lamps the lamp electrodes are heated up to the

electrode emission temperature (warm start) prior to starting to achieve long life and

tolerance to frequent on/off switching.

With the electronic control gear used, these two conditions are met by a series

resonance circuit, whose resonating for OSRAM DULUX® EL LONGLIFE lamps is

deliberately delayed by a PTC thermistor (preheat phase).

In the case of OSRAM DULUX® EL VARIO, OSRAM DULUX® EL FACILITY and

OSRAM DULUX® EL SENSOR Plus, preheating of the filament and starting of the

lamp are closely controlled by an integrated circuit (OSRAM DULUX® IC).

A radio interference filter prevents the generator frequency and its harmonics from

affecting the supply cables.

Thanks to the electronic control gear, an OSRAM DULUX® EL can be operated on any

standard mains frequency and is not affected by fluctuations in the mains frequency.

Certain lamp types can also be operated on DC voltage (see 3.5.2).

230 V

50 Hz

325 V

Interference

filter

Smoothing

Rectifier

High frequency

generator

Current limiting

choke

lamp

Pre-

heat

circuit

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