- functions: wind meter
- measurement: wind speed and direction
- small size
- low price
- two cable connection
- digital measurement result transmission
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Meter LB-747 is designed for measurement of wind speed and direction horizontal component. The meter is made basing on the mechanical WSD1 elements - that are produced in England. It is characterized by small size and low weight. It can be made in a version for wind speed measurement only (without a direction measurement - LB-747P). The meter is especially designed for work in small, portable meteorological stations.
The wind meter is made out of two sensors: a speed sensor and a wind
direction sensor as well as a measurement converter. The meter's
casing is made out of anodized aluminum alloys. The speed sensor has a
small inertia vane made out with ABS (what assures quick response)
placed on a double bearing made from stainless steel. Each vane
rotation generates one impulse on the reed relay output. The direction
sensor is dynamically balanced and is coupled with a potentiometer. The
signals form the sensors are delivered to a measurement converter,
placed in an additional casing on a mast or immediately in a
meteorological station's casing (i.e. LB-741).
The electronic meter system is secured by a silicone filing compound which makes it resistant to high humidity and additionally has a metal screen which protects is (to some extent) against atmospheric discharge.
The vane rotations are transferred to the magnet movements causing
for the reed relay to short circuit. The impulse frequency coming from
the reed relay is measured using the microprocessor's meters. The
wind's direction is transferred to the position of the potentiometer's
sliding head, which voltage is measured by the analog - digital
converter integrated with the microprocessor. The electrical signals
coming from the sensors are counted by the microprocessor - the
calibration values stored in the device's memory are also taken into
consideration. Additionally the wind's direction measurement results
are averaged by taking the last eight measurements - in such a way the
moment sensor oscillations around the perpendicular axis are
eliminated.
The measurement results are sent from the device in a digital form
(current loop) to a supervisory system of data collection:
The interface parameters allow on sending data and powering the
device using one two cable screened line of any polarity, what makes
the installation process a lot easier. The length of the transmission
line is limited only by the resistance of the cable used (resistance of
both cable wires cannot exceed 100 om).
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The meter is assembled using an extension arm, offered as an additional meter's equipment. An extension arm is fastened to a horizontal mast from 30 to 50 mm in diameter. An example way of assembling on the meteorological station's mast using the extension arm is introduced on the picture below.
In order to secure the wind meter against the atmospheric discharge one should add to the set a lighting protector installation which should be placed next to the meter according to the general ways of using it. It is recommended to complement the cable connection with the cooperating device for a protector, i.e. a subscriber telephone protector type OA-1.
| SPEED SENSOR |
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|---|---|
| Calibration |
1 impulse for 1,493 m |
| Maximum wind speed |
90 m/s |
| Minimal wind speed |
0,5 m/s |
| Accuracy |
2 % |
| Linearity |
2 % |
| DIRECTION SENSOR |
|
| Rotation range |
360 ° (with no end) |
| Scope of work measurement |
357 ° |
| Accuracy | 3 % |
| Linearity | 0,5 % |
| SET OVERALL DIMENSIONS |
|
| Height |
280 mm |
| Diameter (maximum) |
240 mm |
| Weight (without a converter) |
500 g |
| OTHER PARAMETERS |
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| Measurement resolution |
speed: 0.1 m/s |
| direction: 1 ° | |
| Power supply |
voltage 8...24V DC, |
| current 15...25 mA. | |
| Interfejs | digital current loop |
| Scope of work temperatures |
-20...+70 °C |
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Produced by: LAB-EL Laboratory Electronics 68b, Bodycha Str., 02-495 Warsaw tel: (022) 667 71 18, 0601 209656, fax: (022) 867 53 32 e mail: info@label.com.pl home page: http://www.label.com.pl internet meteorological station: http://www.meteo.waw.pl meteorological station on a mobile phone: wap.meteo.waw.pl Last updated: 09.05.2004 |
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