USER'S GUIDE ® Vaisala HUMICAP Humidity and Temperature Transmitters HMD70U/Y U303EN11
PUBLISHED BY Vaisala Oyj P.O. Box 26 FIN-00421 Helsinki Finland Phone (int.): +358 9 8949 1 Fax: +358 9 8949 2227 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.
HMD70U/Y Transmitters Operating Manual U303en-1.1 Contents 1. PRODUCT DESCRIPTION ................................................................................................... 1 2. TO BE NOTED WHEN MEASURING HUMIDITY .................................................................. 2 3. INSTALLATION.................................................................................................................... 3 4. 5. 3.1 Selecting the place of installation .............................
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HMD70U/Y Transmitters Operating Manual U303en-1.1 1. PRODUCT DESCRIPTION The HMD70 transmitters are duct mounted three-wire transmitters for the measurement of humidity (HMD70U) and for the measurement of humidity and temperature (HMD70Y). The HMD70U/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.
HMD70U/Y Transmitters Operating Manual 2. U303en-1.1 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.
HMD70U/Y Transmitters Operating Manual U303en-1.1 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.
HMD70U/Y Transmitters Operating Manual 3.3 U303en-1.1 Grounding Open the lid and mount the cable bushing set 18941HM. Do the grounding according to Figure 3.3. When connecting the signal cable to the transmitter housing, fold the cable braid between the brass disk in order to achieve the best possible EMC performance. Do not leave the bare shield of the connected wires so that it can shortcircuit the electronics! flexible wires 0.
HMD70U/Y Transmitters Operating Manual U303en-1.1 3.4 Electrical connections and installation of the current module Figure 3.4 shows the electrical connections and the installation of the current module. INSTALLATION OF THE CURRENT MODULE 18945HM OUTPUT SELECTIONS T 0...1V RH 0...5V T RH 0...10V T RH 0...20mA current module T RH 1. Take off the jumpers T RH 1 2. Connect the module; note the right direction! 3. Connect the power supply 1 1 TEST CONNECTOR U U U U current module 0...
HMD70U/Y Transmitters Operating Manual 3.4.1 U303en-1.1 Connection to an AC supply The HMD70U/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 3.4.1.1).
HMD70U/Y Transmitters Operating Manual U303en-1.1 3.5 Electronics LID TO REMOVE THE SENSOR HEAD: 1. Open the lid 2. Disconnect the screw terminal 3. Open the screws (2 pcs) 4. Pull out carefully SCREW TERMINAL TO REINSTALL THE SENSOR HEAD: 1. Push in the sensor head 2. Fasten the screws 3. Connect the screw terminal 4. Close the lid SCREWS 18941HM GLANDS 10528HM SPARE PART SENSOR HUMICAP180 MEMBRANE FILTER part no. 17039HM Figure 3.5 1997-07-31 STAINLESS STEEL SINTERED FILTER part no.
HMD70U/Y Transmitters Operating Manual U303en-1.1 4. CALIBRATION 4.1 One-point humidity 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.
HMD70U/Y Transmitters Operating Manual U303en-1.1 4.3 Calibration table Temperature *) LiCl 4...20 mA 0...20 mA 0...1 V 0...5 V 0...10 V °C °F %RH mA mA V V V 15 59 *) 20 68 11.3 5.81 2.26 0.113 0.565 1.13 25 77 11.3 5.81 2.26 0.113 0.565 1.13 30 86 11.3 5.81 2.26 0.113 0.565 1.13 35 95 11.3 5.81 2.26 0.113 0.565 1.13 NaCl 4...20 mA 0...20 mA 0...1 V 0...5 V 0...10 V %RH mA mA V V V 75.6 16.10 15.12 0.756 3.780 7.56 75.5 16.08 15.10 0.755 3.775 7.55 75.3 16.05 15.06 0.753 3.765 7.53 75.
HMD70U/Y Transmitters Operating Manual U303en-1.1 6. TECHNICAL DATA 6.1 Relative humidity Measurement range 0...100 %RH Accuracy at 20 °C: %RH 3 2 1 0 -1 0 10 20 30 40 50 60 70 80 90 100 %RH 50 60 70 80 -2 -3 Temperature dependence: %RH 2.0 1.5 1.0 0.5 0 -20 -0.5 -1.0 -1.5 -2.0 6.2 -10 0 10 20 30 40 °C Response time (90%) at +20 °C in still air 15 s with membrane filter Humidity sensor HUMICAP180 Temperature (Y model only) -20...+80 °C Measurement range Accuracy: °C 0.
HMD70U/Y Transmitters Operating Manual U303en-1.1 6.3 General Supply voltage range depends on the selected output signal. When AC supply is used, an isolated source is recommended. The current outputs require an optional output module, part no.18945HM. 0...1 V 0...5 V 0...10 V 0...20 mA (RL = 0 Ω) 0...20 mA (RL = 500 Ω) DC 10...35 V 14...35 V 19...35 V 10...35 V 20...35 V AC 9...24 V 12...24 V 16...24 V 11...24 V 17...24 V Factory setting 0...1V. Other outputs selectable by jumper connections.
HMD70U/Y Transmitters Operating Manual 6.4 U303en-1.1 Electromagnetic compatibility The emission and immunity tests have been performed according to standards EN50081-1 and EN50082-1. 6.4.
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