EKO MS-80 - About Recalibration Procedures

EKO INSTRUMENTS CO., LTD. - Pyranometer MS-80/80S/80U - Instruction Manual Ver. 1
Pg. 70
A-6. About recalibration
When recalibrating at a recalibration center other than EKO, the calibration scale of the other center may differ
slightly from the pyranometer calibration scale and sensitivity constants (μV/Wm
-2
) obtained by EKO. The
differences may be caused by differences in the calibration method, differences in the reference standard,
measurement uncertainty, and measurement conditions.
If a new sensitivity constant was found and needs to be applied to the pyranometer, it can be applied in two ways:
1) (Post data correction) Multiply the relative difference of the irradiance value measured with the pyranometer.
In this case, the original factory sensitivity value given by EKO remains unchanged. When the new sensitivity
figure was found apply the ratio of the new and original calibration figure according to the formula below:
I
new
[W/m
2
] =
Example:
It was proven that there was a relative difference in irradiance measured by MS-80S and the reference
pyranometer. In this example the irradiance measured by MS-80S was lower than the irradiance measured by
the reference pyranometer, a new sensitivity value can be calculated and applied by the following equation.
S
new
= I
MS80S
/ I
ref
x S
original
S
new
New MS-80S Sensitivity (μV/W/m
2
)
S
origin
MS-80S Original Sensitivity (μV/W/m
2
)
I
MS80S
Irradiance measured by MS-80S (W/m
2
)
I
ref
Irradiance measured by reference pyranometer (W/m
2
)
Note: We recommend to change the sensitivity figure only when the new sensitivity figure exceeds a certain
number based on the uncertainty bands (U) of the original and new calibration according to the formula.
[S
new
-S
original
] / √[(U
new
^2+U
original
^2 )] <1
2) (Change the sensitivity figure of the MS-80S) Set a new sensitivity figure to the MS-80S.
This can be done by done through the Hibi software. Connect the MS-80S to a PC with a RS485/USB converter
cable. In settings, the new sensitivity figure can be applied. The original sensitivity figure remains, but wil be
replaced by the “last" sensitivity figure (μV/W/m
2
). Multiple calibration figures can be stored inside the
pyranometer, the “last” sensitivity figure is the actual one to calculate the irradiance.
S
new
[μV/W･m
-2
]
E [
μ
V]
S
original
[μV/W
･
m
-2
]
S
original
[μV/W
･
m
-2
]
X