Kipp&Zonen CFR Calibration Facility - Manual (Page 23)

CFR manual
22
The Kipp & Zonen reference pyranometers are calibrated at the WRC with the sun and sky as the radiation
source. As a consequence, in principle, the calibration values obtained for test pyranometers when using
the CFR are related to the same outdoor conditions as in Davos. The specific conditions are given in the
extended calibration certificate that accompanies the reference pyranometer. A small correction is applied
to convert from the solar elevation angle at the time of the reference calibration, to normal incidence
(vertical) radiation, as used in the CFR.
4.11 Mountings for other radiometers
A range of optional turntables and adapters is available for mounting other Kipp & Zonen radiometers and
some models of pyranometers from other manufacturers. These can be easily be exchanged with the
standard Kipp & Zonen mounting provided with the CFR.
4.12 Stopwatch
The stopwatch provides accurate timing of the calibration. It is necessary to perform the calibration with the
steps of the procedure timed as exactly as possible to overcome the fact that the response time of some
pyranometers is in the order of magnitude of 2 minutes for 99% response. Good timing is the key to optimal
repeatability.