Vaisala HMD60Y, HMD60U User Manual

®

USER'S GUIDE

Vaisala HUMICAP

Temperature Transmitters

Humidity and

HMD60U/Y

U301EN11

PUBLISHED BY
Vaisala Oyj Phone (int.): [phone]

P.O. Box 26 Fax: [phone]
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.

HMD60U/Y Transmitters

U301en-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 Grounding................................................................................................................4

3.4 Electrical connections.............................................................................................5

3.5 Electronics ...............................................................................................................6

4. CALIBRATION .....................................................................................................................7

4.1 One-point humidity calibration...............................................................................7

4.2 Two-point humidity calibration...............................................................................7

4.2.1 Two-point humidity calibration procedure ...................................................7

4.3 Calibration table......................................................................................................8

5. MAINTENANCE....................................................................................................................8



5.1 Replacing the HUMICAP

6. TECHNICAL DATA...............................................................................................................9

6.1 Relative humidity.....................................................................................................9

6.2 Temperature (Y model only) ...................................................................................9

6.3 General...................................................................................................................10

6.4 Electromagnetic compatibility..............................................................................11

6.4.1 Emissions................................................................................................11

6.4.2 Immunity .................................................................................................11

GUARANTEE .....................................................................................................................1 1

180 sensor and the filter ..............................................8

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HMD60U/Y Transmitters
Operating Manual U301en-1.1

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HMD60U/Y Transmitters

U301en-1.1 Operating Manual

1. PRODUCT DESCRIPTION

The HMD60 transmitters are duct mounted two-wire transmitters for the
measurement of humidity (HMD60U) and for the measurement of humidity
and temperature (HMD60Y).

The HMD60U/Y transmitters are easy to install and maintain: the electronics
can be disconnected without dismantling the installation. 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 HMD60Y transmitters
measure temperature with the reliable Pt 1000 sensor.

1997-07-31 1

HMD60U/Y Transmitters
Operating Manual U301en-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 HUMICAP180 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

2 1997-07-31