Jahresbericht 08 - PMOD/WRC
Jahresbericht 08 - PMOD/WRC
Jahresbericht 08 - PMOD/WRC
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Solar Radiometry Section (<strong>WRC</strong>-SRS)<br />
Wolfgang Finsterle<br />
The record number of calibration items, participation<br />
in the U.S. National Pyrheliometer Comparisons at the<br />
National Rewnewable Enregy Laboratory (NREL) in<br />
Golden, Colorado, and the manufacturing of a new series<br />
of ten PMO6-cc absolute radiometers were the<br />
highlights of 20<strong>08</strong>.<br />
As discussed in the Operational Services section of this<br />
report the technical staff of the Solar Radiometry Section<br />
(SRS) was busy with calibrating a record number of instruments<br />
during the 20<strong>08</strong> calibration season. At times the<br />
calibration facilities were reaching their capacity limits as<br />
was the data acquisition system. To avoid future overload<br />
the already planned modernization and extension of the<br />
calibration platform for pyranometers was expedited. A<br />
new concrete foundation was built on the old measuring<br />
field to accommodate the new platform after the calibration<br />
season had ended in October. The new platform itself<br />
will be installed in spring 2009.<br />
New Data Acquisition System<br />
With the new calibration platform the bottleneck will shift to<br />
the current 72-channel data acquisition system. Because<br />
this system is already more than 20 years old it was decided<br />
to replace rather than upgrade it. Two competitive<br />
tenders from different suppliers were evaluated. We eventually<br />
decided to buy an integrated system based on the<br />
PXI (PCI eXtension for Instrumentation) standard. For testing<br />
and validation purposes it is planned to operate the new<br />
384-channel system in parallel with the old system during<br />
2009. Once the respective quality management documents<br />
will be adapted accordingly the new PXI system will<br />
be dedicated to the calibration duties within the SRS.<br />
Pyrheliometer Comparisons<br />
The SRS participated with two transfer instruments in the<br />
National Pyrheliometer Comparisons at NREL in Golden,<br />
Colorado, USA (Fig. 1) from September 22 to October 3.<br />
The WRR-calibrated transfer instruments PMO6-0401 and<br />
AHF-32455 confirmed the agreement of the US national<br />
standard group with the World Radiometric Reference<br />
(WRR). Regular intercomparisons with national and regional<br />
standards also provide confidence in the stability of the<br />
WRR.<br />
A new series of PMO6-cc absolute radiometers was built<br />
during 20<strong>08</strong>. Twenty detector heads but only ten control<br />
units were initially built. The reduced number of control<br />
units was thought as a measure to save cost but high customer<br />
demand actually warrants construction of control<br />
units for all 20 detector heads. The new series ‘<strong>08</strong>’ features<br />
a modernized look and improved control electronics components<br />
(Fig. 2).<br />
Operational Services 7<br />
Figure 1. At the US National Pyrheliometer Comparisons the WRRcalibrated<br />
transfer instruments AHF-32455 (right, top) and PMO6-0401<br />
(right, bottom) share a solar tracker with two other PMO6s.<br />
Figure 2. While technically identical to its tried predecessors the<br />
PMO6-cc body of the new ‘<strong>08</strong>’ series has an appealing new exterior.
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