Xylem WE100 User Manual

Global Water

800-876-1172 • globalw.com

00-671
Publication Number 38320112

Global Water

Instrumentation, Inc.

151 Graham Road

P.O. Box 9010

College Station, TX 77842-9010

T: 800-876-1172

Int’l: [phone], F: [phone]

Barometric Pressure: WE100
Solar Radiation: WE300
Wind Speed: WE550
Wind Direction: WE570
Humidity: WE600
Temperature Sensor: WE700
Solar Shield: WE770

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Global Water

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Congratulations on your purchase of the Glob al Water Weather Sensor. This
instrument has been quality tested and approved for providing accurate and
reliable measurements. We are confi dent that you will find the sensor to be a
valuable asset for your application. Should you require assistance, our
technical staff wil l be ha ppy to help.

Table of Contents

I. Checklist

• • • • • • • Page 3

II. Inspection

• • • • • • 3

III. General Sensor Installation

• • • • 4

IV. Barometric Pressure Sensor

• • • • 5

V. Solar Radiation Sensor

• • • • • 7

VI. Wind Speed Sensor

• • • • • 8

VII. Wind Direction Sensor

• • • • • 9

VIII. Humidity Sensor

• • • • • • 10

IX. Temperature Sensor

• • • • • 11

X. Solar Shield

• • • • • • 12

XI. Maintenance

• • • • • • 12

XII. Troubleshooting

• • • • • • 13

XIII. Warranty

• • • • • • • 15

XIV. Appendix A: Temperature Calibration Check

• • 16

XV. Appendix B: 2 Wire Sensor Measurement Diagr am

• 17

XVI. Appendix C: 3 Wire Sensor Measurement Diagram

* Copyright  Global Water Instrumentation, Inc. 2002

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I. Sensor Checklist

a. Weather Sensor
b. Weather Sensor Manual

II. Inspection

a. Your Weather sensor was carefully inspec ted and certified by our

Quality Assurance Team before shipping. If any damage has occurred
during shipping, please notify Global Water Instrumentation, I nc . and
file a claim with the carrier involved.

Use the checklist to ensure that you hav e r ec eived every thing needed
to operate the weather instrument( s ) .

Global Water

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III. Genera l Sensor Installation

a. Weather sensors have many applications and ther efore many

installation options. The sensors s hould be loc ated in a clear area on
a level surface.

b. Install your Weather sensor so t hat it is easily accessible for calibration

purposes. You may need to remove and reinstall it in the future, so
plan ahead!

c. All G lobal Water Weather sensors produce a 4-20 mA output signal.

4-20 mA is an industrial standard signal for proc ess control monitoring.
Most PLCs (Programmable Logic Controller) , RTUs (Remote
Telemetry Unit), and data acquisition s y s tems accept this signal
directly. If the system only accepts volt age s ignals , the sensor output
must be converted to a voltage signal by reading t he v oltage across a
precision resistor in series with t he s ignal wir e. Since Ohms Law
states that V = IR, if the 4-20 mA signal is dropped across a 250 ohm
resistor, the output will be 1 to 5 volt s DC. If the 4-20 mA signal is
dropped across a 125 ohm resistor, the out put will be halved to 0.5 to

2.5 VDC. The 4-20 signal wire is connected to the datalogger v oltage
input terminal. The resistor is plac ed between this input and the
ground terminal of the datalogger’s bat tery. The power (or voltage to
the sensor) must be connected to positive bat tery terminal of the
datalogger.

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d. The sensors may be pulsed on or turned on by the logging sys tem

prior to taking a reading. Use a warm up time appropriate to t he
Weather sensor you are using to assure t hat t he sensor is fully on.
The sensors can run continuously for real t im e applications . Each
sensor draws between 4 and 20 mA depending on whether the sensor
is reading at the minimum or maximum of its r ange.

e. Weather sensors may be stored without any s pecial provis ions . Place

the sensor inside a bag to keep the sensor clean and stor e on a s helf
or hang it on a wall.

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IV. Barometr ic P r essure Sensor

a. Barometric Pressure sensor specifications.

Output: 4-19mA
Range: 800-1100 mill ibars
Accuracy: +1% of full scale
Operating Voltage: 10-36VDC
Current Draw: Same as sensor output
Warm Up Time: 3 seconds minimum
Operating Temperature: -40° to +55°C
Size of Probe: 3”x2”x1”
Weight: .13 lb.

b. The sensor is a two-wire sensor using the red wire for power and the

black wire for the output signal. Warni ng : Always conn ect th e
sensor with the power turned off.

c. The bar om etric pressure sensor may be stored without any s pec ial

provisions. Place the sensor inside a bag to keep t he s ens or c lean
and store on a shelf or hang it on a wall.

d. When you read a barometer the reading direct ly from it is the "station

pressure."

Two things affect the barometer's r eading, the high or low air pressure
caused by weather systems, and the air pressure caused by the
station's elevation, or how high it is abov e s ea lev el. No matter what
weather systems are doing, the air's pr es s ur e decreases with height. If
you're trying to draw a weather map of air pressure patterns, you need
a way to remove the effects of the station's elevation. That is, you want
to see what the pressure would be at the st ation if it were at sea level.

You need to calculate, sea-level pressure, which is defined as: "A
pressure value obtained by the theoretical reduction of barometric

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pressure to sea level. Where the Earth's s ur face is above sea level, it
is assumed that the atmosphere extends to s ea level below t he s tation
and that the properties of that hypothetical atmosphere are related to
conditions observed at the station." To do t his , you have to take into
account the barometric reading at the station, the elevation above sea
level, and the temperature.

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