Omega TX905 User guide

TX905

Field Rangeable Voltage
Input Two-Wire Transmitter

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User’s Guide

O

N

Servicing

North America:

U.S.A.:

ISO 9001 Certified

One Omega Drive, Box 4047
Stamford, CT 06907-0047
Tel: [phone]
FAX: [phone]
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For immediate technical or

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Sales Service: 1-800-826-6342 /1-800-TC-OMEGA

®

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It is the policy of OMEGA Engineering, Inc. to comply with all worldwide safety and EMC/EMI regulations that apply. OMEGA is constantly pur­suing certification of its products to the European New Approach Directives. OMEGA will add the CE mark to every appropriate device upon
certification.

The information contained in this document is believed to be correct, but OMEGA accepts no liability for any errors it contains,
and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, human applications.

Benelux:

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The Netherlands
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Toll Free in Benelux: 0800 0993344
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OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords our customers
the latest in technology and engineering.OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 2005 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied, reproduced,
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OMEGA ENGINEERING, INC.

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Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE RETURNING ANY
PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETURN (AR) NUMBER FROM OMEGA’S CUSTOMER
SERVICE DEPARTMENT (IN ORDER TO AVOID PROCESSING DELAYS). The assigned AR number should then be marked on the
outside of the return package and on any correspondence. The purchaser is responsible for shipping charges, freight, insurance
and proper packaging to prevent breakage in transit.

Servicing Europe:

FOR WARRANTY RETURNS, please have the following
information available BEFORE contacting OMEGA:

1.Purchase Order number under which the product was

PURCHASED,

2. Model and serial number of the product under warranty, and

3.Repair instructions and/or specific problems relative to the

product.

FOR NON-WARRANTY REPAIRS,

consult OMEGA
for current repair charges. Have the following
information available BEFORE contacting OMEGA:

1. Purchase Order number to cover the COST of the repair,

2. Model and serial number of the product, and

3.Repair instructions and/or specific problems relative to the

product.

France:

11, rue Jacques Cartier, 78280 Guyancourt, France
Tel: [phone] FAX: [phone]
Toll Free in France: 0800 466 342
e-mail: [email protected]

Germany/Austria:

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Tel: [phone] FAX: [phone]
Toll Free in Germany: 0800 82 66342
e-mail: [email protected]

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M44 5BD, United Kingdom
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Toll Free in United Kingdom: 0800-488-488
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TX905, TX906
Voltage Input Two-Wire Transmitter

Page

Section 1 Introduction 1

1.1 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.3 Models Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Section 2 Installation 8

2.1 Mounting the TX905 or TX906 . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.2 Wiring the TX905 or TX906 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

TABLE OF

CONTENTS

0i

TX905, TX906
Voltage Input Two-Wire Transmitter

Page

Section 3 Calibration Instructions 16

3.1 Equipment Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2 Calibration Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Section 4 Troubleshooting Guide 21
Section 5 Accessories 23
Section 6 Specifications 24

TABLE OF

CONTENTS

ii

1.1 General Description

The OMEGA®TX905 or TX906 Voltage Input Two-Wire Transmitter will
produce a standard 4-20 mA output signal proportional to that
produced by its Voltage Input. Transmission of the proportional current
output may be accomplished by using inexpensive copper wire.

01

1

Introduction

1 Introduction

Figure 1-1 TX905, TX906

Transmitter

O

N

Figure 1-2 Dimensions (in inches)

2

03

Introduction 1

The TX905 or TX906 transmitter is normally powered by an
unregulated power supply as shown in Figure 1-3. The
proportionally-transmitted signal begins at 4 mA, at the low end of
its voltage range, and increases to 20 mA, at the high end of its
voltage range.

1

4

Introduction

Figure 1-3 TX94 RTD Transmitter

Introduction 1

05

The TX905 or TX906 two-wire transmitter works with voltage inputs and
provides an output current of 4-20 mA proportional to the input. Two copper
wires now carry the 4-20 mA output signal and dc voltage to operate the
transmitter, thereby reducing possible noise pick-up errors. The TX905 or TX906
does NOT provide isolation between its input and the 4-20 mA output.

6

1.2 Features

• 4-20 mA output

• Ⳳ0.1% full-scale accuracy

• Upscale break protection

• Low Cost

1 Introduction

Introduction 1

1.3 TX905, TX906 Models Available

07

TX905 Field rangeable millivolt transmitter, 4 to 64 mV
TX906-V1 Field rangeable millivolt transmitter, 0.04 to 0.64 mV
TX906-V2 Field rangeable millivolt transmitter, 0.40 to 6.40 mV
TX906-V3 Field rangeable millivolt transmitter, 4 to 64 mV

Model Number Description

8

2

Installation

2.1 Mounting the TX905 or TX06

The TX905 or TX906 transmitter may be:

1. surface mounted,

2. mounted inside a protection head (refer to Figure 2-1), or

3. installed into the OMEGA mounting track (part number RT)
using an OMEGA mounting bracket (part number TX90-BR).

4. installed into standard 35mm DIN rail using an OMEGA
DIN rail mounting adapter (part number TX-90-DIN).

Figure 2-2 shows the RT mounting track. Figure 2-3 shows the
TX90-BR mounting bracket.

09

Figure 2-4 shows a typical installation of two transmitters using the
bracket and mounting track. Figure 2-5 shows the TX90-DIN rail
mounting adapter.

Figure 3-1 Assembly of the Transmitter inside

Protection Head

Installation 2

10

2 Installation

CAUTION

Hand tighten
transmitter
mounting
screws only.
Do not
overtighten.

Figure 2-2 RT Mounting Track (Dimensions in inches)

11

Installation 2

Figure 2-3 TX90-BR Mounting Bracket (Dimensions in inches)

12

2 Installation

Figure 2-4 Installation with the Bracket and Track (Dimensions in inches)

13

Installation 2

Figure 2-5 TX 90-DIN DIN Rail Mounting Adapter (Dimensions in inches)

14

2 Installation

2.2 Wiring the TX905 or TX906 (Refer to Figure 2-6)

1. Connect a dc power supply in series with the load to the
(+PS) and (-PS) power terminals. Note that the load (usually
a monitoring instrument) may be connected to either the
(+) or (-) power lead.

2. Connect the RTD element to the input terminals as shown.

15

Installation 2

Figure 2-5 Wiring Diagram for the TX905 or TX906

O
N

16

3

Calibration Instructions

3.1 Equipment Required

• Precision voltage source, such as the OMEGA®CL8301 dc
voltage and Current Calibrator

• Precision DMM capable of measuring mA, within 0.001 mA

resolution and Ⳳ0.002 mA accuracy.

17

3.2 Calibration Procedures (Refer to Figure 3-1)

Connect the calibration equipment according to Figure 3-1.
Standard copper test leads are used.

To check or adjust the calibration:

1. Locate the Z (zero) and S (span) potentiometers.

2. Select, from Table 3-1, the correct dip switch settings for your
desired range for the TX905 or TX906.

If a Precision Voltage Simulator is used, such as the OMEGA

®

Model CL8301 Precision Calibrator, select the Voltage Input Z
(zero) and S (span) values.

Calibration Instructions 3

18

3 Calibration Instructions

For example, if you selected an input range of 10 to 50 mV for the
TX905, the Z input is 10.000 mV and the S input is 50.000 mV.

3. Set the calibrator to the selected Z (zero) voltage value.
Adjust the Z potentiometer to read 4.000 mA on the monitoring
instrument.

4. Set the calibrator to the selected S (span) voltage value.
Adjust the S potentiometer to read 20.000 mA on the monitoring
instrument.

5. Repeat steps 3 and 4, as required, until the readaings are exactly

4.000 mA and 20.000 mA. This procedure is necessary since there is
interaction between the two potentiometers.

19

Calibration Instructions 3

5

4

–PS

OSZO

+PS

–IN
+IN

3

2

1

TX905

or

TX906

SPAN

DVM
(4-20 mA)
MONITOR

250 OHMS

(–)

(–)

(+)

(+)

ZERO
COPPER
WIRE

PRECISION
VOLTAGE SIMULATOR
OMEGA CL8301

DC SUPPLY 7-35 VDC
WITH 250Ω LOAD, DC
SUPPLY MUST BE AT
LEAST 5V MORE FOR

THE 250Ω LOAD, OR

12-35V

Figure 3-1 TX905 or TX906 Voltage Calibration Set-Up

20

4 Calibration Instructions

Table 4-1. Calibration Values for the TX905 AND TX906

MODEL INPUT SPAN

TX906-V3 4/8V 8/16V 12/24V 16/32V 20/40V 24/48V 28/56V 32/64V

TX906-V2 .4/.8V .8/1.6V 1.2/2.4V 1.6/3.2V 2.0/4.0V 2.4/4.8V 2.8/5.6V 3.2/6.4V

TX906-V1 .04/.08V .08/.16V .12/.24V .16/.32V .20/.40V .24/.48V .28/.56V .32/.64V

TX905 4/8V 8/16V 12/24V 16/32V 20/40V 24/28V 28/56V 32/64V

SW4 ON OFF ON OFF ON OFF ON OFF

SW5 ON ON OFF OFF ON ON OFF OFF

SW6 ON ON ON ON OFF OFF OFF OFF

POSITION SWITCH SETTING

21

4

Troubleshooting Guide

Malfunction or incorrect operation may be caused by:

1. Incorrect Readings:
Check for improper wiring (Refer to Figure 2-5)

2. Loose or broken wires:
Check each terminal connection for tightness. Move each wire­back and forth and note any changes in operation.

3. Too high a load resistance in the output current loop or too
low a current rating on the power supply:

a) Measure the total resistance of each device (excluding the

transmitter and power supply) in the 20 mA loop, including
the resistance of the lead wires.

22

4 Troubleshooting Guide

b) Calculate maximum allowable loop resistance using the

formula: Loop Resistance (maximum) = V

supply

–7V

For example, a 24V power supply would give a maximum loop

resistance of: 17V/0.020A = 850 ohms.

c) Make sure the power supply is rated for at least 28 mA

times the number of TX905 or TX906 transmitters being powered.

For example, if the supply is powering five transmitters, the

supply should be rated for at least 140 mA.

0.020A

23

5

Accessories

Model No. Description

TX90-BR Mounting Bracket
PSU-24B Unregulated Power Supply, 24 Volts
TX828 Process Loop-Powered Indicator
RT 48" Mounting Track
TX90-DIN DIN Rail Mounting Adapter
RAIL -35-2 6.5' Section 35mm DIN Rail

24

6

Specifications

General

Size: 1.75" dia. X 1.25" high (includes terminal strip)

Span Adjustment TX905 4 to 64 mV switch selectable

TX906-V1 .04 to .64 switch selectable
TX906-V2 .4 to 6.4 switch selectable

TX906-V3 4 to 64 switch selectable
Zero Adjustment ±25% of span
Power Supply Voltage
Operating Range: +7 Vdc to +35 Vdc, 28 mA max required

per transmitter

25

Specifications 6

Accuracy: ±0.1% of full scale (includes effects of hysteresis, (re-

peatability and linearity proportional to the RTD input)
Frequency Response: 3dB@ 3Hz
Ambient Temperature: -13°F to 185°F (-25°C to 85°C)
Storage Temperature
Range: -85°F to 257°F (-65°C to 125°C)
Thermal Zero Shift: <0.01%/°F of span (span >10 mV)

<0.02%/°F of span (span = 5 to 10 mV)
Thermal Span Shift: <0.01%/°F of span
Weight: 1.0 oz (29g)

26

6

Specifications

Output

Current Output Span: 4-20 mA dc

Current Output
Limits: 3 to 28 mA, typical

Maximum Loop
Resistance: (V

supply

– 7V)/0.020A = ohms

Load Resistance Effect: 0.01% of span per 300 ohms change

Power Supply Effect: 0.002% of output span per volt

27

Specifications 6

Input

Sensor: millivolt or voltage output transducer

Source Current: (TX905) 4 nA TYP
Input Resistance: (TX905) >30 MEGOHMS
Input Resistence: (TX905) 226 K

28

7

Notes

7

Notes

29

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a period of 13 months from
date of purchase. The OMEGA®WARRANTY adds an additional one (1) month grace period to the normal one (1) year product
warranty to cover handling and shipping time. This ensures that OMEGA’s customers receive maximum coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Service Department will issue an Authorized
Return (AR) number immediately upon phone or written request. Upon examination by OMEGA, if the unit is found to be defective, it will
be repaired or replaced at no charge. OMEGA’s WARRANTY does not apply to defects resulting from any action of the purchaser, including
but not limited to mishandling, improper interfacing, operation outside of design limits, improper repair, or unauthorized modification. This
WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence of having been damaged as a result of
excessive corrosion; or current, heat, moisture or vibration; improper specification; misapplication; or misuse or other operating conditions
outside of OMEGA’s control. Components in which wear is not warranted, include but are not limited to contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However, OMEGA neither assumes
responsibility for any omissions or errors nor assumes liability for any damages that result from the use of its
products in accordance with information provided by OMEGA, either verbal or written. OMEGA warrants only that the
parts manufactured by the company will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES
OR REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF TITLE, AND ALL
IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF LIABILITY: The remedies of purchaser set forth herein are
exclusive, and the total liability of OMEGA with respect to this order, whether based on contract, warranty,
negligence, indemnification, strict liability or otherwise, shall not exceed the purchase price of the component upon
which liability is based. In no event shall OMEGA be liable for consequential, incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic Component” under 10 CFR 21
(NRC), used in or with any nuclear installation or activity; or (2) in medical applications or used on humans. Should any Product(s) be
used in or with any nuclear installation or activity, medical application, used on humans, or misused in any way, OMEGA assumes no
responsibility as set forth in our basic WARRANTY/ DISCLAIMER language, and, additionally, purchaser will indemnify OMEGA and hold
OMEGA harmless from any liability or damage whatsoever arising out of the use of the Product(s) in such a manner.

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