USER'S GUIDE
Vaisala HUMICAP®Humidity and
Temperature Transmitters
HMW70U/Y
U304EN12
PUBLISHED BY
Vaisala Oyj Phone (int.): +358 9 8949 1
P.O. Box 26 Fax: +358 9 8949 2227
FIN-00421 Helsinki
Finland
Visit our Internet pages at http://www.vaisala.com/
© Vaisala 2006
No part of this manual may be reproduced in any form or by any means, electronic or
mechanical (including photocopying), nor may its contents be communicated to a third
party without prior written permission of the copyright holder.
The contents are subject to change without prior notice.
Please observe that this manual does not create any legally binding obligations for
Vaisala towards the customer or end user. All legally binding commitments and
agreements are included exclusively in the applicable supply contract or Conditions of
Sale.
HMW70U/Y Transmitters
U304en-1.1 Operating Manual
Contents
1. PRODUCT DESCRIPTION ...................................................................................................1
2. TO BE NOTED WHEN M EASURING HUMIDITY ..................................................................2
3. INSTALLATION....................................................................................................................3
3.1 Selecting the place of installation ..........................................................................3
3.2 Mounting..................................................................................................................3
3.3 Electrical connections and calibration potentiometers.........................................4
3.4.1 Connection to an AC supply ......................................................................5
4. CALIBRATION .....................................................................................................................6
5. MAINTENANCE....................................................................................................................7
5.1 Replacing the HUMICAP
180 sensor and the filter ..............................................7
6. TECHNICAL DATA...............................................................................................................8
6.1 Relative humidity.....................................................................................................8
6.2 Temperature (Y model only) ...................................................................................8
6.3 General.....................................................................................................................9
6.4 Electromagnetic compatibility..............................................................................10
6.4.1 Emissions................................................................................................10
6.4.2 Immunity .................................................................................................10
GUARANTEE .....................................................................................................................10
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U304en-1.1 Operating Manual
1. PRODUCT DESCRIPTION
The HMW70 transmitters are wall mounted transmitters for the measurement
of humidity (HMW70U) and for the measurement of humidity and temperature
(HMW70Y).
The HMW70U/Y transmitters can be mounted directly on the wall. They are
easy to install and maintain. One point calibration is easily performed with the
HMI41 indicator and the calibration cable 19116ZZ.
Both transmitter types incorporate the HUMICAP®180 humidity sensor which
uses an operating principle based on changes in the capacitance of a thin
polymer film as it absorbs water molecules. The HMW70Y transmitters
measure temperature with the reliable Pt 1000 sensor.
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Operating Manual U304en-1.1
2. TO BE NOTED WHEN MEASURING HUMIDITY
In the measurement of humidity and especially in calibration, it is essential
that the temperature equilibrium is reached. Even a slight difference in the
temperature between the measured object and the sensor causes an error. For
example, at +20 °C (+ 68 °F) and 50 %RH, a temperature difference of +1 °C
between the measured object and the sensor causes an error of +3 %RH. If
relative humidity is 90 %RH, the error is about +5.4 %RH.
The error is at its greatest when the temperature of the sensor differs from that
of the surroundings and the humidity is high. A few degrees’ difference in
temperature may cause water to condense on sensor surface. Efficient
ventilation accelerates evaporation whereas in an unventilated space, it may
take hours. The HUMICAP180 sensor returns to its normal functioning as
soon as water has evaporated. Any contaminated water condensing on the
sensor may shorten its life span and change the calibration.
10
9
8
7
6
5
4
dRH (%RH)
3
2
1
0
-40-200 20406080100
Temperature (°C)
Figure 2.1 Measurement error at 100 %RH when the temperature
difference between th e ambient and the sensor i s 1 °C
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U304en-1.1 Operating Manual
3. INSTALLATION
3.1 Selecting the place of installation
Select a place that gives a true picture of the environment or process and is as
clean as possible. Air should circulate freely around the sensor. A rapid air
flow is recommended as it ensures the same temperature for the ambient air
and the sensor head.
Install the transmitter in a place where no cold or hot spot can develop. If the
sensor head is installed in a duct or channel where the temperature is different
from the ambient temperature, insulate the point of entry. An uninsulated
installation might lead to condensation on the sensor head and even if no
condensation occurs, the resultant air flow may change the temperature near
the sensor head and distort the readings.
3.2 Mounting
The HMW70U/Y transmitters can be mounted directly on the wall. First attach
the base plate with the two screws provided. Thread wires through the opening
in the transmitter board. Note the UP sign which shows the correct mounting
position. Be careful not to damage the HUMICAP®180 sensor.
33 (1.30)
85 (3.35)
110 (4.33)
Figure 3.2 Dimensions of the HMW70U/Y (in mm)
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Operating Manual U304en-1.1
3.3 Electrical connections and calibration potentiometers
Signal cables are connected to a removeable 5-pole screw connector. Make
connections according to Figure 3.3.
RH test connector (X5) is used with the HMI41 indicator for one point
calibration.
-
DC/AC
POWER SUPPLY
V/mA
OUTPUT SELECTIONS
0-1V
T
RH
V/mA
5
4
3
2
1
+
GND
Tout
RHout
Us
T
RH
UP
Test
X5
0-5V
0-10V
T
RH
T
RH
(dry)
RH
offset
sensor
T
(wet)
RH
gain
HUMICAP180
RH sensor
Figure 3.3 Electrical connections
T gain
T offset
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U304en-1.1 Operating Manual
3.4.1 Connection to an AC supply
The HMW70U/Y transmitters can also be connected to an AC supply without
an external rectifier. However, when more than one transmitter is connected to
one AC transformer, a common loop is formed and there is an increased risk
of a short-circuit. To avoid this, use a separate floating supply for each
transmitter (see Figure 3.4.1). However, if several transmitters have to share
one transformer, the phase (∼) must always be connected to Us connector in
each transmitter.
VAC
VAC
VAC
HMW70U/Y transmitter
Us
Us
GND
GND
HMW70U/Y transmitter
HMW70U/Y transmitter
Us
GND
Us
GND
RH/T
RH/T
RH/T
RH/T
Controller
signal
signal
Controller
signal
shared
common line
signal
HMW70U/Y transmitter
Figure 3.4.1 Connection to an AC supply
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Operating Manual U304en-1.1
4. CALIBRATION
The accuracy is recommended to be checked at least once a year; the interval
depends on the operating conditions and the required accuracy of the
measurement. The transmitter calibration can be conveniently checked with
the HMI41 indicator equipped with an appropriate probe and optional
calibration cable. If adjustment is needed, use the one-point calibration
potentiometer.
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U304en-1.1 Operating Manual
5. MAINTENANCE
5.1 Replacing the HUMICAP180 sensor and the filter
Remove the damaged sensor and insert a new one. Handle the sensor by the
plastic socket. DO NOT TOUCH THE SENSOR PLATE. Recalibrate the
transmitter.
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Operating Manual U304en-1.1
6. TECHNICAL DATA
6.1 Relative humidity
Measurement range 0...95 %RH
(output signal corresponds to 0...100 %RH)
Accuracy at +20 °C:
%RH
3
2
1
0
10 4020 605030 8070 %RH
0 90 100
-1
-2
-3
Temperature dependence:
%RH
1.0
0.5
0
-0.5
-1.0
200
10 30 50-10
Response time (90%) at 20 °C in still air 15 s
Humidity sensor HUMICAP180
6.2 Temperature (Y model only)
Measurement range -5...+55 °C
Accuracy:
°C
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-10 100
20
40 60 °C
40
6030°C
50
Linearity better than 0.1 °C
Temperature sensor Pt 1000 IEC 751 class B
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6.3 General
Supply voltage range depends on the selected output signal.
When an AC supply is used, an isolated source is recommended.
DC AC
0...1 V 10...35 V 9...24 V
0...5 V 14...35 V 12...24 V
0...10 V 19...35 V 16...24 V
Factory setting 0...1 V. Other outputs selectable by jumper connections.
An output change causes an error which is less than 0.5 %RH
without recalibration.
Operating temperature range -5...+55 °C
Storage temperature range -40...+80 °C
Long-term humidity range for electronics 0...85 %RH
Housing:
cover ABS plastic
base plate PA
Connections Screw terminals 0.5...1.5 mm
2
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6.4 Electromagnetic compatibility
The emission and immunity tests have been performed according to standards
EN50081-1 and EN50082-1.
6.4.1 Emissions
Test Setup according to Performance
Radiated interference EN55022 class B
6.4.2 Immunity
Test Setup according to Performance
Electrostatic discharge IEC 801-2:1991 criteria B
Electrical fast transients IEC 801-4:1988 criteria B
RF radiated fields IEC 801-3:1984 criteria A
*GSM-field immunity ENV50204:1995 criteria A
(* additional test)
GUARANTEE
Vaisala issues a guarantee for the material and
workmanship of this product under normal operating
conditions for one year from the date of delivery.
Exceptional operating conditions, damage due to
careless handling or misapplication will void the
guarantee.
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