NovaLynx presents the following wind sensors and anemometers:
- 200-WS-02 Anemometer & Vane
- 200-WS-23 Current Loop Wind Sensor
200-WS-02 ANEMOMETER & VANE
This series of WeatherPort Wind Sensors are moderately priced quality transducers designed for general application. A combination of injection molded thermoplastic, anodized aluminum, and stainless steel parts contribute to reliable operation in adverse environments.
These sensors are easy and inexpensive to maintain. The combination three cup anemometer and wind vane units utilize an in-line configuration, eliminating the need for a crossarm.
The anemometers produce a series of output pulses having a frequency directly proportional to wind speed. Wind direction is measured by a balanced vane coupled to a 20k ohm conductive plastic potentiometer. With a constant excitation voltage of less than 15 volts, the output from the wiper arm is proportional to the wind azimuth angle.
The 200-WS-02E Wind Sensor assembly consists of two major parts: an anemometer for measuring wind speed and a wind vane for measuring horizontal wind direction. The complete sensor assembly has been designed with the wind vane mounted on top of the anemometer for stability and ease of signal transmission. Output signal transmission is accomplished through a five-conductor, twenty-four gauge, shielded cable.
Anemometer
The anemometer uses a three-cup and hub assembly to sense wind velocity. As the wind blows past the cups, the pressure of the wind against the insides of the cups causes them to rotate. There are three permanent magnets embedded in the hub that holds the cups. Each magnet, as it rotates past a fixed point on the sensor base, activates a magnetic reed switch mounted in the base. Three closures of the reed switch will be produced for each revolution of the cup assembly. The contacts of the magnetic reed switch capsule are normally open; the contact will close each time a magnet passes over it. The ratio of closed-to-open time is nominally 1/10 of the total period for a revolution of the wind cups. This duty cycle may change slightly as the sensor ages and with exposure to temperature extremes.
The anemometer is rated for wind speeds up to 125 miles per hour and has a starting threshold of approximately 1 mile per hour. The magnetic reed switch capsule is rated to carry a maximum current of 10.0 milliamperes with an applied voltage of no more than 50 volts AC or DC. The approximate speed constant for the anemometer is 1.25 mph/Hz.
Wind Vane
The wind vane is coupled to a 20K ohm, ±20%, single turn potentiometer. The linearity of the potentiometer is ±1%. Maximum power dissipation should be limited to 1/4 watt. Resolution is infinite over potentiometer's 355 degree arc. There is a gap ("dead band") of approximately 5 degrees between the ends of the resistive media. As the wind blows 2 past the vane, the design of the counter-weight and the tail fin align the point of the counter-weight into the wind. Fluctuations in the wind direction are measured by the sensor as the aerodynamics of the counter-weight and the tail try to keep aligned to the path of the wind. The motion of the wind vane is translated to the potentiometer shaft causing a change in the potentiometer's resistance. Connecting the potentiometer wires to a voltage source allows easy measurement of the wind direction as a change in voltage.
200-WS-23 CURRENT LOOP WIND SENSOR
The 200-WS-23 Current Loop Wind Sensor monitors wind speed and direction. The electronics converts the raw signals from the wind sensors to proportional 4 to 20 mA current loop values for use by process control or monitoring systems. It acts like a variable resistance that draws 4-20 mA when powered with 8 to 30 Vdc. No external power is required because the encoding electronics for wind speed and for wind direction are isolated and powered from their respective 2-wire current loops.
Two versions are offered. The 200-WS-23 measures both wind speed and direction, while the 200-WS-23S measures wind speed only. Both systems consist of two subassemblies, a wind sensor and a signal conditioning electronics package in a NEMA housing. Although it has only one PC board, it contains two completely independent circuits, one for wind speed and one for wind direction.
The NovaLynx Model 200-WS-23 Current Loop Wind Sensor measures wind speed and direction and convert each measurement into a 4-20 mA output signal for use by process controls or monitoring systems. External power is not required since the encoding electronics for wind speed and for wind direction are isolated and powered from their respective 2-wire current loops. The 200-WS-23 measures both wind speed and direction, and contain two subassemblies; the wind sensor and the signal conditioning electronics assembly.
The WS-23S uses the 200-WS-01B Wind Speed Sensor, which consists of anemometer without the wind vane. The sensor is ruggedly constructed using UV-resistant ABS plastic and anodized aluminum parts. The cable connecting the pole-mounted wind sensor to the encoder electronics package is typically 40 feet in length but may be extended for a total length of 250 feet. The encoded current loop signals are capable of being transmitted over distances of up to several miles. The electronics package is supplied inside a gasketed NEMA enclosure.
Wind Sensor
The wind sensor is the rotating assembly with the three cup anemometer and wind vane for measuring wind speed and wind direction. The wind vane is mounted onto a common axis with the anemometer and includes a tail fin with a nose weight that provides balance. The wind vane is coupled to an angular encoder that is housed within the sensor's cylindrical weather skirt.
Encoder
The encoder electronics package is housed within a gasketed NEMA enclosure. The circuitry contains two independent 4-20 mA data channels, one for wind speed and one for wind direction. Each channel receives its power from its respective 2-wire measurement loop.
