SMA SC 200 - Manual (Page 51)

SMA Solar Technology AG Analog Inputs
User Manual SC-BEN100262 51
Example calculation: pyranometer
A pyranometer has an output voltage of 0 to 10 volt, which corresponds to an irradiation between 0
and 1350 W/m
2
.
Example if M = 5 V
Example calculation: temperature sensor
A thermometer with measurement transducer outputs 4 to 20 mA, which corresponds to a temperature
range of –30 to 80 °C.
Example if M = 4 mA:
Ml = 0 V Mu = 10 V
Dl = 0 W/m² Du = 1350 W/m²
Formula Calculation
G = (Du - Dl) / (Mu - Ml) G = (1350 - 0) / (10 - 0) = 135
O = Dl - (G * Ml) O = 0 - (135 x 0) = 0 W/m
2
Formula Calculation
D = (G x M) + O 135 x 5 + 0 = 675
Ml = 4 mA Mu = 20 mA
Dl = –30 °C Du = 80 °C
Formula Calculation
G = (Du - Dl) / (Mu - Ml) G = (80 - (-30)) / (20 - 4) = 6.875
O = Dl - (G x Ml) O = (–30) – (6.875 x 4) = –57.5 °C
Formula Calculation
D = (G x M) + O 4 x 6.875 + (–57.5) = –30