Delta SS1-UM-1.05 User Manual download pdf (Page 66)

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• Technical Reference section Document code: SS1-UM-1.05

Checking the PAR calibration

Various techniques for checking the SunScan system PAR calibration and

consistency are described in the Measurement Options, PAR calibration section,

which you should refer to. This also includes advice on when to use the

recalibrate

and restore factory calibration procedures.

Factory calibration method

A standard PAR Quantum sensor provides the reference value of PAR that the Beam

Fraction sensor and the SunScan probe are set up to. This process is carried out

under a near-daylight spectrum lamp in controlled conditions.

Re-setting the factory calibration

The electronic components and photodiodes used in the PAR circuits of the Beam

Fraction sensor and SunScan probe are very stable and are not expected to change

for the lifetime of the instrument.

Circuit adjustment facilities in the Beam Fraction sensor are provided for the initial

factory set-up and are not intended to be used for routine adjustment thereafter. The

probe factory calibration cannot be adjusted without specialist equipment.

Warning! Do not attempt to change the factory calibration without referring back to

Delta-T first. The most likely cause of an apparent change of calibration is physical:

dirt in the grooves around the BFS diffusers, or dirt or staining of the probe diffuser.

If after checking the above you still have:

• a Beam Fraction sensor with badly matched Total and Diffuse outputs, or

• a SunScan probe with an out-of-spec calibration, or individual diode readings that

appear faulty,

please refer back to your agent or the factory.

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Delta SS1-UM-1.05 User Manual Page 66