Vaisala HMP45D User Manual
USER'S GUIDE
Vaisala HUMICAP® Humidity and
Temperature Probes
HMP45A/D
U274EN-1.2
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.
HMP45A and HMP45D
U274en-1.2 Operating Manual
1. GENERAL
The HMP45A and HMP45D probes are designed for the measurement of
relative humidity and temperature. Humidity measurement is based on the
capacitive thin film polymer sensor HUMICAP180. Temperature
measurement is based on resistive platinum sensors (Pt 100 and Pt 1000).
Both the humidity and temperature sensors are located at the tip of the probe
and in standard version protected by a membrane filter. The HMP45A and
HMP45D have a similar humidity output, but the temperature output is active
in HMP45A (voltage output 0-1V) and passive in HMP45D (resistive output
Pt 100).
2. CONNECTIONS
The cable wires are connected as shown in Figure 1.
HMP45D
HMP45A
YEL OUTPUT
0...1V=-40...+60 ˚C
BLU V+ 7...35VDC
BRN OUTPUT
0...1V=0... 100%RH
VIO GND
RED GND (SENSE)
GREY (SHIELD)
YEL
WHT
GRN
BLK
GREY (SHIELD)
Pt100
Pt100
Pt100
Pt100
BLU 7...35VDC
BRN OUTPUT 0...1V=0...100%RH
VIO GND
RED GND (SENSE)
Figure 1 Wire colours
Pt100
SIGNAL GROUND is used for output signal in a differential measurement. With
SIGNAL GROUND, the cable can be extended up to 100 metres without
disturbing the measurement accuracy. When outputs are not measured against
SIGNAL GROUND, connect GROUND and SIGNAL GROUND to the same point.
1
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