Apogee TS-100 Kullanıcı El Kitabı - Sayfa 14

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Ayrıca Apogee TS-100 için: Kullanıcı El Kitabı (19 sayfalar)

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Fan Operation:

Under some environmental conditions (e.g., high wind speed, low solar radiation), accurate

measurements can be made without running the fan at full speed. Fan speed and power consumption

can be decreased using a pulse width modulation (PWM) signal. The PWM signal should have a

frequency of approximately 20 kHz and a duty cycle of 50 to 100 %, where a duty cycle of 100 % is full

power and 50 % is low power. Running the fan in a low power mode reduces the current drain from 80

mA to approximately 25 mA. The only way to completely stop the fan is to turn the power off.

The fan also has a tachometer to monitor blade revolutions per minute (RPM). The tachometer outputs a

pulse voltage signal. The pulse multiplied by 30 yields fan RPMs. The RPM should be near 4500 in full

power mode and 2500 in low power mode. In addition to the tachometer output wire, there is a pull-up

wire (power input). This allows a user-defined maximum output voltage from the tachometer, and

facilitates interfacing with multiple measurement devices.