Working principle of anemometer

Commonly used instruments for measuring wind speed are cup-shaped anemometer, wing-shaped anemometer, catameter, and hot-ball electric anemometer. Wing-shaped and cup-shaped anemometers are easy to use, but their inertia and mechanical friction resistance are large, and are only suitable for measuring large wind speeds.
Hot-ball electric anemometer
1. The principle of construction is an instrument that can measure low wind speed, and its measuring range is 0.05-10m / s. It is composed of two parts: hot bulb probe and probe. The probe has a glass ball with a diameter of 0.6mm. The ball is wrapped with a nickel-chromium wire ring for heating the glass ball and two thermocouples connected in series. The cold end of the thermocouple is connected to the phosphor copper pillar, which is directly exposed to the airflow. When a certain amount of current passes through the heating ring, the temperature of the glass ball rises. The degree of increase is related to the wind speed. When the wind speed is small, the degree of increase is large; otherwise, the degree of increase is small. The magnitude of the increase is indicated on the meter by a thermocouple. According to the meter reading, check the calibration curve to find out the wind speed (m / s).
2. How to use â‘  Before use, observe whether the pointer of the meter is pointing at the zero point. If there is a deviation, you can gently adjust the mechanical adjustment screw of the meter to return the pointer to the zero point;
â‘¡ Put the calibration switch in the off position;
â‘¢ Insert the plug of the measuring rod into the socket, the measuring rod is placed vertically upwards, the screw plug is pressed tightly to seal the probe, the "calibration switch" is placed at the full scale position, and the "full scale adjustment" knob is slowly adjusted so that the meter pointer points at Full-scale position
â‘£Set the "correction switch" to the "zero position" and slowly adjust the two knobs "coarse adjustment" and "fine adjustment" so that the pointer of the meter is at the zero position;
⑤ After the above steps, gently pull the plug to expose the probe (the length can be selected according to need), and make the red dot on the probe face the wind direction. According to the meter reading, refer to the calibration curve and check. Out of the measured wind speed;
⑥After measuring a few minutes (about 10min), the above steps ③ and ④ must be repeated once to standardize the current in the instrument; ⑦ After the measurement, the "correction switch" should be placed in the off position.
3. Precautions â‘  This instrument is a more precise instrument, which is strictly protected from collision and vibration, and cannot be used in places with too much dust or corrosiveness.
â‘¡ There are 4 batteries in the instrument, which are divided into two groups, one is three series, one group is single. When adjusting the "full scale adjustment" knob, if the meter cannot reach full scale, it means that the single battery has been exhausted; when adjusting the "coarse adjustment" and "fine adjustment" knobs, if the meter pointer cannot return to zero, it means that Three batteries have been exhausted; when replacing the battery, open the small door at the bottom of the instrument and connect it in the correct direction.
â‘¢After maintenance, the instrument must be recalibrated.


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