Vaisala LT31 - Figure 24 Interface Unit Receiver LTI211; Power Supply FSP102

User's Guide ______________________________________________________________________
56 __________________________________________________________________ M210667EN-C
0806-036
Figure 24 Interface Unit Receiver LTI211
The interface unit supplies the power required for the measurement unit
and the optional heater and the optional Obstruction Light LT31OBS.
The receiver interface unit LTI211 contains an interface and power
supply connection for the optional Background Luminance Sensor LM21
and the transmitter interface unit LTI111 provides an interface and power
supply for the PWD Forward Scatter Sensor.
The external power inputs and the communication interfaces of LT31 are
located in the interface units. All external interfaces are equipped with
surge protection circuitry.
Power Supply FSP102
The power supply board (see Figure 25 on page 57) includes AC and
secondary fuses, the AC voltage level switch and the transient protection
circuitry. The operation of the AC power supply is indicated with two
LEDs. The green LED indicates that the non-stabilized power supply
output of nominal 24VDC is available and the yellow LED indicates that
the 28VAC output is functional.