Vaisala LM21 - LM21 Operational Specifications; LM21 Optical Specifications; LM21 Electrical Specifications

User's Guide ________________________________________________________
58 _____________________________________________________ M210283en-A
Operational Specifications
Table 12 Operational Specifications
Property Description / Value
Measuring range 2 ... 40 000 cd/m²
Measurement accuracy 10 %
Optical Specifications
Table 13 Optical Specifications
Property Description / Value
Spectral response 400 ... 700 nm, resembles the
spectral response of the human eye
Peak wavelength 550 nm
Field of view 6°
Effective diameter of
reception lens
24 mm
Electrical Specifications
Table 14 Electrical Specifications
Property Description / Value
Connection Power/signal cable provided
Power supply 10 VDC to 38 VDC, or alternatively 8
VAC to 28 VAC, 6 W
Heater power supply 28 VAC, 50 W
Output signal RS-485 (RS-232), frequency output
Output signal frequency
of LM21FD and
LM21MITRAS
1.4 ... 3000 Hz
(corresponds to 4 ... 30 000 cd/m²)
Output signal amplitude
of LM21FD and
LM21MITRAS
12 V