Working principle of Cup Anemometer
It is comprised of a cup generator (windspeed sensor) bolted onto the top of a wind vane (direction sensor). The whole of this assembly is mounted on a common support tube terminating in a base mounting casting which incorporates the cable entry for the transmit cables.
The wind vane (direction sensor) is of light alloy construction and houses a transmit magslip rotated through a gear train by the movement of the fin arm. One complete revolution of the fin arm produces one complete revolution of the transmit magslip.
50 volts AC is supplied to the transmit magslip by a mains transformer mounted near the receiving and recording instruments and this same supply is fed to the receive magslip in the recording instrument. A synchronous link is formed between the transmit and receive magslips by three cores of cable resulting in a slavish following of the receiver magslip to movement of the fin arm.
Signals from the cup generator (windspeed sensor) are fed through 2 cores of cable to recording instruments.
Orientation between the magslip and the north stamped on the base casting is set during manufacture thus installation of the anemometer on site is simplified to aligning this stamping to true north with a compass.