Vaisala WS425 Technical data

Vaisala Instruments Catalog 2009

Ref. B210768EN rev. A

P.O. Box 26, FI-00421 Helsinki, FINLAND

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Tel: [phone]

Fax: [phone]

www.vaisala.com/WS425

WS425 Ultrasonic Wind Sensor for Critical Wind
Measurement Applications

Features/Benefits

• Superior data availability and accu-

racy in all wind directions due to
the patented three transducer layout

• No maintenance needed

• eoretical mean time between

failures (MTBF) 26 years

• Eects of temperature, humidity and

pressure fully compensated

• Large transducer heads are

insensitive to rain

• RS232/485/422, SDI-12 and analog

outputs

• Operates with 10 ... 15 VDC,

additional 36 VDC required for
heated model

• Stainless steel as standard sensor

material

• Field verication device available

e WS425 denes the new
standard of accurate wind
measurement.

• Can be mounted upside down

• US National Weather Service relies

on Vaisala ultrasonic technology

e Vaisala Ultrasonic Wind Sensor
WS425 gives meteorologists an
alternative to the cup and vane
mechanical sensors. With its continuous
data availability, the WS425 is also ideal
for a variety of wind measurement
applications in aviation, road and railway
safety and energy production.

Accurate and maintenance­free

e WS425 has no moving parts, and
is resistant to contamination and
corrosion. In addition to improving
accuracy and the reliability of data in
all wind conditions and climates, the
WS425 eliminates on-demand and
periodic maintenance.

Measurement based on
ultrasound

e WS425 uses ultrasound to
determine horizontal wind speed and
direction. e measurement is based
on transit time, the time it takes for
the ultrasound to travel from one
transducer to another, depending on
the wind speed.

T-O-F

e transit time is measured in both
directions for a pair of transducer
heads. Using two measurements for
each of the three ultrasonic paths at
60° angles to each other, the WS425
computes the wind speed and
direction.

e wind measurements are calculated
in a way that completely eliminates the
eects of altitude, pressure, temperature
and humidity.

Standard and heated
models

e heated model has thermostatically
controlled heaters in the transducer
heads to prevent freezing rain or snow
build- up. e standard model operates
with a low current 10 ... 15 V supply. For
the heated model, an additional 36 V
supply is used for heating.

Outputs

SDI-12 provides the most extensive set
of commands and calculations. e
standard RS-232/485/422 protocol
supports NMEA and three other
message formats. Analog outputs are
available as an option.

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Technical Data

WIND

Vaisala Instruments Catalog 2009

Ref. B210768EN rev. A

WS425

Wind speed

Measurement range
serial output 0 ... 65 m/s (0 ... 144 mph, 0 ... 125 knots)
analog output 0 ... 56 m/s (0 ... 124 mph, 0 ... 107 knots)
Starting threshold virtually zero
Delay distance virtually zero
Resolution 0.1 m/s (0.1 mph, 0.1 knots, 0.1 km/h)
Accuracy (range 0...65 m/s) ± 0.135 m/s (±0.3 mph, ±0.26 knots)
or 3% of reading, whichever is greater

Wind direction

Measurement range 0 ... 360°
Starting threshold virtually zero
Delay distance virtually zero
Resolution 1°
Accuracy (wind speed over 1 m/s) ±2°

Outputs

Digital outputs
type RS232, RS422 or RS485,
four dierent message formats
bit rate adjustable from 1200 to 19200 bit/s
available averages RS232: 1 to 9 seconds
SDI-12 Standard Data Interface
type 3 wires for ground, signal and supply
bit rate xed 1200 bit/s
available averages 1 to 3600 seconds
Analog outputs
wind speed
frequency 5 Hz/mph
voltage 8.0 mV/mph
output impedance 10 kohm
wind direction
simulated potentiometer 0 ... V
reference voltage 1.0 ... 4.0 V
output impedance 24 kohm

represents 0 ... 359°

ref

General

Operating power supply 10 ... 15 VDC, 12 mA typical (analog)
and for heated model 36 VDC ±10 %, 0.7 A
Operating temperature
WS425 non-heated –40 ... +55 °C (-40 ... +131 °F)
WS425 heated –55 ... +55 °C (-67 ... +131 °F)
Material
body stainless steel (AISI 316)
sensor arms stainless steel (AISI 316)
transducer heads silicone rubber
Dimensions
height 355 mm (14")
width 250 mm (10")
depth 286 mm (12")
Weight 1.7 kg (3.7 lbs)

Complies with EMC standard EN61326-1:1997 + Am1:1998 +
Am2:2001; Generic Environment

Accessories

Cable supporting analog outputs, 10 m ZZ45204
Cable supporting RS-232 outputs, 10 m ZZ45203
Cable supporting RS-485/422 outputs, 10 m 010411
Cable supporting SDI-12 outputs, 10 m WS425CABSDI
Adapter for 30-35 mm
(1 1/4") diameter vertical tube WS425FIX30
Adapter for 60 mm
(2 1/4") diameter vertical tube WS425FIX60
Bird Perch WS425BIRDPERCH
Field verier WS425VERIFIER

Response characteristics

maximum reading rate 1 per second
sonic measurement time 0.2 s
signal processing time 0.15 s
response time 0.35 s

Specications subject to change without prior notice.
©Vaisala Oyj

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