Emerson SL-31080 User Manual

TEMPERATURE /HUMIDITY TRANSMITTER - WALL (4-20 MA)

Description

The THW420 combination temperature/humidity transmitter is designed to meet applications that require local indication of both temperature and humidity in a single, aesthetically pleasing enclosure.

This device incorporates a 10K ohm (Ω) platinum RTD. The transmitter requires 24 VDC. The sensor provides an accurate and predictable four-wire, 4-20 mA output signal for temperature and a second 4-20 mA output signal for humidity.

Dimensions

0.95"

(241mm)

0.75"

(191mm)

SIDE

VIEW

Wall

4.5"

(1143mm)

FRONT

VIEW

2.25"

(572mm)

2.75"

(699mm)

TOP VIEW

Specifications

Output 4 to 20 mA Sensor 10K Ω platinum RTD Supply Voltage 24 VDC Tolerance of Resistance

(Accuracy) Response Time 20 seconds for a 63% step Environmental Operating

Range (Transmitter)

±1.5°F (±0.83°C) ±2% RH (from 15 to 95% RH)

45°F to 96°F; 0 to 100% RH (7°C to 35°C); 0 to 100% RH

Termination

The THW420 transmitter must be powered from a 24 VDC supply. The combination temperature/ humidity sensor is terminated as follows:

•The humidity transmitter requires a three-wire termination for the 4-20mA output using 24 VDC.

•The temperature sensor also requires a three- wire termination. In most cases, it obtains power from the analog input to which it is connected and no external power is required.

Though interference from external sources is not a major problem with current transmitters, Liebert recommends separating the wiring from line voltage wiring and from wiring used to supply highly inductive loads such as motors, generators and coils. Liebert also recommends making power connections with twisted pair wire of at least 22 AWG and crimptype connectors.

0-5V

CALRUN

20 H

Products, Inc.

REV. 101600

XCOMBO T&B

To GND (common) of controller*

From +24VDC of controller or power supply

Gnd

V+

Ch1

Ch3

CAL

Te mp

R19

Short

Norm

Open

Ch2

Te mp

T&B

SWITCH

SW1

To controller’s analog input (temperature signal, 4-20mA)

To controller’s analog input (humidity signal, 4-20mA)

* NOTE:

The GND (common) terminal is common between the Power and Sensor

+24VDC should be used at all times

SW2 OUTPUT SELECT

4-20ma

Ch1

4-20ma

Ch2

RESIST.

Ch3

%RH

SW2

DISPLAY CYCLE

IN SECONDS

3 T

POT1

Building Automation

RTH1 RTH2

Terminations

CAUTION

Liebert recommends wiring the sensor WITHOUT power applied because accidental arcing may damage the product and will void the warranty.

Controller

Ground

4-20 mA Input #1 +

4-20 mA Input #2 +

Ordering Information

Quantity Part # Description

THW420 Combination Temperature/Humidity Transmitter Wall 4-20 mA @ 45°F to 96°F and 0 to 100% RH

SL-31080 Product Specification/Installation Sheet page 1 6/03 (Rev. 0)

Mounting

Junction box 2" x 4"

Mounting screws

Cover

Locking screws

Delta base

Wall

Enclosure Mounting Instructions

Mounting hardware is provided for both junction box and drywall installation.

1. Pull the wires through the opening in the base

plate.

2. For junction box installation: Secure the

base to the box using the #6-32 x 1/2" mounting screws provided.

For drywall installation: Drill two 3/16" holes 3-1/4" apart on center. Insert the drywall anchors and secure the base using the #6 x 1" sheet metal screws provided.

3. Terminate the unit according to the guidelines

in Termination on page 1.

4. Attach the cover by latching it to the top of the

base, rotating the cover down and snapping it into place.

5. Secure the cover by backing out the lock-down

screws using a 1/16" allen wrench until they are flush with the bottom of the cover.

NOTE

In a wall-mount application, the wall temperature and the temperature of the air within the wall cavity can cause erroneous readings. The mixing of room air and air from within the wall cavity can lead to condensation and premature failure of the sensor.

To prevent these conditions, seal the conduit leading to the junction box and seal the hole in the drywall by using an adhesive backed, foam insulating pad.

Troubleshooting Guide

The following table lists common problems and possible solutions. For more information, consult your local dealer, Liebert representative or the Liebert Worldwide Support Group.

Problems Possible Solutions

Unit will not operate

Humidity reading is maximum 20 mA or 100%

Humidity reading is minimum 4 mA or 0%

Humidity reading in software appears to be off more than specified accuracy

Temperature sensor in frontend software is reading high

Temperature sensor in frontend software is reading low

• Check +24 VDC power supply at controller.

• Disconnect the sensor and check power wires for +24 VDC.

• Make sure the sensor is installed properly, and is not shorted.

• Quick Check: Remove the sensor. If the reading does not change, contact technical support.

• Verify that the humidity sensor installed.

• Quick Check: Short the sensor terminal block with a wire. Does the reading change? If so, the sensor may be faulty; if not, contact technical support.

• Check all software parameters.

• If available, check the sensor against a calibrated control such as a hygrometer.

• Determine if the sensor is exposed to an external source more than room.

• Make sure wiring is correct.

• Disconnect wires and measure with a multimeter.

• Make sure wiring is correct.

• Disconnect wires and measure with a multimeter.

SL-31080 Product Specification/Installation Sheet page 2 6/03 (Rev. 0)

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