LPPYRHE16
- 12 -
V2.3
5
MEASUREMENT IN THE MODELS WITH ANALOG OUTPUT
Below are the ways to calculate the direct irradiance in the models with analog output
LPPYRHE16, LPPYRHE16AC[S] and LPPYRHE16AV.
5.1
LPPYRHE16
Each pyrheliometer is distinguished by its own sensitivity (or calibration factor) S ex-
pressed in µV/(Wm
-2
) and shown in the label on the pyrheliometer (and in the calibra-
tion report).
The irradiance E
e
is obtained by measuring with a multimeter the difference of potential
DDP at the ends of the sensor and applying the following formula:
E
e
= DDP / S
where:
E
e
is the irradiance expressed in W/m
2
;
DDP is the difference of potential expressed in
µ
V measured by the multimeter;
S is the sensitivity of the pyrheliometer expressed in µV/(Wm
-2
).
5.2
LPPYRHE16AC[S]
The 4…20 mA output signal corresponds to the 0…2000 W/m
2
irradiance range.
The irradiance E
e
is obtained by measuring with a multimeter the current I
out
absorbed
by the sensor and applying the following formula:
E
e
= 125
•
(I
out
- 4)
where:
E
e
is the irradiance expressed in W/m
2
;
I
out
is the current expressed in mA absorbed by the pyrheliometer.
5.3
LPPYRHE16AV
The output signal (0…1 V, 0…5 V or 0…10 V depending on the version) corresponds to
the 0…2000 W/m
2
irradiance range.
The irradiance E
e
is obtained by measuring with a multimeter the output voltage V
out
of
the sensor and applying the following formula:
E
e
= 2000
•
V
out
for the version 0…1 V
E
e
= 400
•
V
out
for the version 0…5 V
E
e
= 200
•
V
out
for the version 0…10 V
where:
E
e
is the irradiance expressed in W/m
2
;
V
out
is the output voltage expressed in V measured by the multimeter.
