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OLICORP
IRS SERIES
07/02/2013
Resistance measurement, closed loop regulation and dead
lamps detection.
Why do we need to measure the resistance ?
As it has been written in previous sections, the lamps resistance is quickly changing according
to the temperature of the filament.
This temperature will strongly be related to the RMS voltage applied to the lamp.
For a more accurate process, it is necessary to account for these variation in the regulation.
What is done by the NS-IRS ?
The purpose of the NS-IRS is to regulate power.
The NS-IRS measures continuously both the voltage and the current applied to the different
lamps. From this measurement, the NS-IRS calculates the RMS Voltage that should be sent to
the lamps with the purpose to control accurately the RMS Power dissipated in the lamps.
From the instantaneous Current and Voltage it is possible to compute the instantaneous value
of the resistance for each lamp.
In the standard implementation of the NS-IRS software, this value is transmitted to the Profibus
DP, for further monitoring.
It is also possible to use only the nominal resistance of the lamps in the power regulation
algorithm. To do so, one has to select the “Use Rnom option” when configuring the NS-IRS
internal settings (PC supervisor setting).
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