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08/09/2023

The anemometer gives false readings. Troubleshooting

Greetings readers! Today we have a problem with the anemometer, which shows the wind speed and direction on the bridge. The readings were stuck in one direction (opposite to the wind). At this speed the wind is displayed correctly.

The anemometer gives false readings. Troubleshooting

What is an anemometer?

An anemometer (or anemoscope) is a weather vane that consists of a generator, a synchronous motor, bearings, gear guides, rings and a brush device. All this can be said in one name - transmitter.

Block diagram of anemometer operation
Block diagram of anemometer operation

When the direction of the wind changes, the weather vane changes its position to the current angle, and at the same time the position of the synchronous motor changes.
Receiver (transformer box)
Receiver (transformer box)

As a result, receiver (transformer box) receives voltage and processes (according to the diagram - a transformer box), and the wind direction is displayed on the panel indicator.

Indicator panel
Indicator panel

Force of the wind measures using a propeller and generator. The voltage of the generator is converted and reads by the voltmeter, which displays the wind speed in meters/sec (or knots) on the panel indicator.

General diagram of the anemometer operation
General diagram of the anemometer operation
Indicator panel
Indicator panel. The anemometer is stuck at 173˚ port side, although it should show about 30˚ starboard side.

From the experience of maritime practice, you can immediately turn to the signal transmitter, because it is who continues the action of the aggressive marine environment, as well as the force of the wind. Most often the problem can be stored there. Therefore, first of all, let's open the weather vane junction box and see what happens to the synchronous motor and brushes.

Synchronous motor and anemometer brush apparatusSynchronous motor and anemometer brush apparatus

Synchronous motor and anemometer brush apparatusSynchronous motor and anemometer brush apparatus
Synchronous motor and anemometer brush apparatus

As a result of an internal check of the anemometer, a problem was discovered with the half-coupling on the synchronous motor shaft, unscrewed mounting bolt (under the hex key). When the weather vane shaft rotated, the motor shaft stood still, so the position of the anemometer was stuck in one position.

Video of the coupling operation

Brushes are a group of thin hairs, which on old anemometers can severely lose their rigidity and intertwine with each other, which also leads to incorrect consequences.

The coupling was retightened, the brush device was cleaned of graphite dust. The readings began to change, but they were still incorrect (180˚ opposite).

Such systems must have a zero calibration. In this case, it can be found on the receiver board.

ZERO SET (zero calibration) on the receiver board
ZERO SET (zero calibration) on the receiver board

You must first fix the weather vane in the zero position so that it does not rotate. The propeller also needs to be fixed (not shown in the photo). You can use an assistant or a rope.

Fixed the transmitter in the zero position (tied it by the tail to the Light tree)
Fixed the transmitter in the zero position (tied it by the tail to the Light tree)

We switched the ZERO SET switch to the right and set the indicator to zero.

Zero on the indicator
Zero on the indicator

After this, the switch returned to its normal position and the weather vane was untied. As a result, the operation of the anemometer was recovered.

If it is not possible to set zero and the anemometer is accurately twisted by 180˚, then you can temporarily reverse the phase on the receiver.

Switching phases on the receiver
Switching phases on the receiver

This is a temporary emergency solution. Subsequently, it will still be necessary to correctly connect the phase and perform a zero calibration.

What other problems could be with the anemometer?

The most common problems that can occur with anemometers are the stuck of the bearings, burning out of the internal components (generator and synchronous motor), which results in the water inside the transmitter.

I also suggest that you read the manufacturer’s instructions for troubleshooting the anemometer.

Troubleshooting anemometerTroubleshooting anemometer
Troubleshooting anemometer

Anemometer (anemoscope) model: Wind sensor (propeller type) AT-200. Heriana

If you had experience in repairing and operating this device, write in the comments to the article or in official groups of site on social networks.

Video of normal operation of the anemometer

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