OSRAM DULUX F - Manual (Page 84)

Economical long-life light sources with plug-in bases
Compact Fluorescent Lamps OSRAM DULUX ®
Technical Guide
82
The necessary auxiliary heating current can also be specified as a function of lamp current by
indicating the total of:
2
2
2
1 Pin Pin
I I
which is called the “Sum of the Squares” of the pin current (SoS)
1 Pin
I and
2 Pin
I are the two pin currents at an electrode in the lamp.
1 Pin
I and
2 Pin
I can be easily
measured on electronic control gear.
As the diagram above shows, there is an ideal target setting for the sum of the squares of the two
pin currents at which the lamp life will be at its optimum. If the sum of the squares of the pin
currents decreases, sputtering will occur at the electrodes. As a result, lamp life will be drastically
reduced.
If the sum of the squares of the pin currents increases with respect to the target value, end
blackening gradually occurs and at very high values for heating the life of the lamp is gradually
reduced due to high thermal evaporation of the emitter material.