BS ISO 15727-2020 UV-C devices – Measurement of the output of a UV-C lamp.
43.2 Malne(lc ballasts
Magnetic ballasts are used to start the UV-C lamp and may be either standard electromagnetic or energy-efFicient electromagnetic. The ballast provides a time-delayed inductive kick with enough voltage to ionize the gas mixture In the tube alter which the current through the tube keeps the lilaments energized. The starter will cyde until the tube lights up. While the IJV.C lamp Ls on. a preheat ballast Is lust an inductor which at the main frequency (50 Hz or 60 Hz) has the appropriate impedance to limit the current to the UV-C lamp to the proper value. Ballasts shall be fairly closely matched to the UV•C lamp in terms of tube wattage, length, and diameter.
4.3.3 ElectronIc ballasts
Electronic ballasts are basically switching power supplies, which eliminate the large, heavy. ‘iron’ ballast in favour of an integrated high frequency inverter/switcher. Current limiting is then done by a very small inductor, which has sufficient impedance at the high frequency. Property designed electronic ballasts are relatively reliable, which depend on the ambient operating temperature, location with respect to the heat produced by the IJV•C lamp as well as other factors.
5 Measurement of (he output of a UV-C lamp
5.1 Measurement method classification
There are two methods to measure the output ola UV-C lamp:
1. Measurement of the output ota lJV-C lamp in a darkroom: Tests in laboratory (also known as static darkroom test) are conducted to ensure the accuracy and consistency o(the measured results;
2. Measurement of the output ola UV-C lamp In a test chamber: For industrial application, the tests In a test chamber shall take account of the Impact of environmental changes in field (such as temperature change and air velocity change). This method is descnbed in Annex B.
5.2 Measurement of the output of a UV-C lamp in a darkroom
The cosine correction for radiometers and spectroradiorneters Is critical to the proper measurement of the UV•C irradiance. The cosine correction shall be confirmed by the following method for each UV.C lamp and ballast combination so that the UV-C lamp measurements are consistent within and between laboratories.
The minimum measurement distance needs to be determined for the given LW-C lamp and UV-C radiometer in order to verily cosine response characteristics of the lJV-C radiometer and reduce its cosine correction error. The method is as follows:
a) Take readings of the lJV-C radiometer for different distances (radiometer position perpendicular to the UV-C lamp axis). see EigureA
b) Take several readings of the UV-C irradiance. For example, moving the radiometer from the closest point to the most remote point and then back again;
c) Average the Irradiance readings for each distance;
d) Calculate the output IJV-C radiation power of the UV-C lamp from the measured irradiance using Formula (1] for each distance:
e) Calculate the output LW-C radiatton power of the IJV-C lamp: plot the calculated UV-C power versus the distance;BS ISO 15727 pdf download.