Campbell Scientific CNR4 Net Radiometer - Manual (Page 48)

Appendix B. CNF4 Heater/Ventilator Appendix B. CNF4 Heater/Ventilator
10 watt power available?
Not available
DO NOT HEAT
Available Consider options below tions below
Clock and relay available?
Not Available
DO NOT
B-2
10 watt power available?
Not available
DO NOT HEAT
Available Consider op
Clock and relay available?
Not Available
DO NOT HEAT
(recommendation)
Available
Heat from 1 hour before sunset until
1 hour after sunrise.
The heater power can be controlled using one of the SW12V channels of the
Campbell Scientific dataloggers. The heater’s current drain is approximately
850 mA at 12 Vdc (10 watts). The ventilator draws additional 5 watts of power
at 12 Vdc. Connect the power ground from the heater to a G terminal close to
the SW12V channel of the datalogger (not to an analog ground near the
measurement inputs).
The heater power can be controlled by the datalogger program. For example,
the datalogger program can turn on the heater only when the light level falls
below 20 W/m
2 or, if a measurement of air humidity is available, when the dew
point of the air falls to within 1ºC of the sensor body temperature.
Do not use the SW12 channel of a CR1000 or CR3000 to
simultaneously power the heater and ventilator.
Simultaneously powering the heater and ventilator will
exceed the current limit of the SW12 channel. If the heater
and ventilator need to be used at the same time, connect
the CNF4 to the 12V channel instead of the SW12 channel
and use an external relay to switch the power on and off.
Refer to Section 4.2 of the CR1000 and CR3000 manual
for details on the 12V current source limits.
CAUTION
B-2