Datasheet

Guide to Starters Page 5 of 17
4 Starters ST 111 / ST 151 (LONGLIFE starters)
4.1 Design
The glow starter contains the actual starter element, the glow igniter, and the radio interference suppression
capacitor.
It is connected parallel to the lamp in series with the lamp electrodes.
Typical design of a glow igniter:
Figure 1: Design of a glow igniter
The filling mostly comprises a mixture of inert gas (neon, argon, helium) with hydrogen under a pressure of
20 to 100 mbar.
Bimetals consist of two different metal strips pressed one on the other which have different coefficients of
thermal expansion.
4.2 Operation
Figure 2: Fluorescent lamp circuit, preheating and starting operations for a fluorescent lamp
When line voltage is applied glow (partial) discharge starts between the bimetallic contacts. The applied
voltage is higher than the partial discharge inception voltage and the closure voltage.
The glow current (I
G
20-40mA) heats up the bimetallic electrodes. These start to bend and touch each other
once they have reached a certain temperature. This short-circuit causes glow discharge to stop. The full
short-circuit current (I
V
) of the choke then flows through the lamp electrodes.
Canister
Glass bulb
Bimetallic electrodes
Pinch (UK), Stem (US)
Radio interference suppression capacitor
Cover plate
Brass bolts (contacts)