Delta-T SPN1 User Manual

Also see for SPN1: Technical note

Delta-T SPN1 User Manual Manual pdf 27 page image

Calibration procedure and traceabilityFactory calibration procedureThe SPN1 is calibrated at the factory against a transfer standard SPN1.Calibration is done before the shadow mask is fitted, so that all thethermopile sensors can be uniformly exposed. Units are calibrated in a 12inch integrating sphere with a light source which approximately matchesbright sunlight in intensity and spectral composition. The calibration factorsrequired for each of the seven sensors are calculated and programmedinto the SPN1. This matches the production unit to the reference, andspreads any cosine responsevariations evenly over the wholerange of zenith angles.After the shadow mask is fitted,the SPN1 reading is checkedagain in the calibration lamp rig.The transfer standard SPN1s areperiodically checked outside overa period of several weeks and arange of climatic conditions,against a solar tracker andshading disk system using twoKipp CM6B double domereference pyranometers. Thesereferences are calibrated againstUK national standards via a KippCM21 secondary transferstandard.Recalibration of SPN1We recommend that SPN1s are returned every 2 years to Delta-T forrecalibration. A calibration certificate similar to that on the next page willbe provided.A full recalibration of the SPN1 is not possible without disassembling theSPN1, and requires special light sources.SPN1 User Manual v1.0 Technical reference z 27