Campbell CNR4 Manual de Instruções descarregar pdf (Página 58)

Appendix D. CNF4 Heater/Ventilator

10 watt power available? Not available

DO NOT HEAT

Available

Consider options below

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 W). The ventilator draws additional 5 W 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

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 datalogger’s switched 12 V channel to

simultaneously power the heater and ventilator.

Simultaneously powering the heater and ventilator will

exceed the current limit of the switched 12 V channel. If the

heater and ventilator need to be used at the same time,

connect the CNF4 to the 12V channel instead of the

switched 12 V 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

D-2

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Campbell CNR4 Manual de Instruções Página 58