Omega Products OMEGA-CJ Installation Manual

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User’s Guide

OMEGA®CJ

Thermocouple Cold-Junction Compensators

Shop online at

OMEGAnet®On-Line Service Internet e-mail

omega.com [e-mail]

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:

Managed by the United Kingdom Office
Toll-Free: 0800 099 3344 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

Czech Republic:

Frystatska 184, 733 01 Karviná, Czech Republic
Toll-Free: 0800-1-66342 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

France:

Managed by the United Kingdom Office
Toll-Free: 0800 466 342 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

Servicing Europe:

U.S.A. and Canada:

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

®

Customer Service: 1-800-622-2378/1-800-622-BEST

®

Engineering Service: 1-800-872-9436/1-800-USA-WHEN

®

U.S.A.: ISO 9001 Certified

OMEGA Engineering, Inc.
One Omega Drive, P.O. Box 4047
Stamford, CT 06907-0047 USA
Toll-Free: 1-800-826-6342 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

Servicing North America:

For immediate technical or application assistance:

Mexico:

En Español: 001 [phone]
FAX: [phone]
[e-mail]
e-mail: [e-mail]

Germany/Austria:

Daimlerstrasse 26, D-75392 Deckenpfronn, Germany
Toll-Free: 0 800 6397678 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

United Kingdom:

ISO 9001 Certified

OMEGA Engineering Ltd.
One Omega Drive, River Bend Technology Centre
Northbank , Irlam, Manchester M44 5BD England
Toll-Free: 0800-488-488
TEL: [phone]
FAX: [phone]
e-mail: [e-mail]

Canada:

976 Bergar
Laval (Quebec), Canada H7L 5A1
Toll-Free: 1-800-826-6342 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

i

SECTION PAGE

SECTION 1 INTRODUCTION .........................................................1

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

1.2 Features ...........................................................................................1

SECTION 2 UNPACKING .................................................................2

SECTION 3 OPERATION ..................................................................2

3.1 Operating Procedure .....................................................................2

3.2 Battery Replacement ......................................................................4

3.2.1 Battery Life ......................................................................................4

3.2.2 Replacing the Battery ....................................................................4

SECTION 4 THEORY OF OPERATION .........................................5

SECTION 5 CALIBRATION ..............................................................7

SECTION 6 SPECIFICATIONS .........................................................8

TABLE OF

CONTENTS

OMEGA®CJ THERMOCOUPLE
Cold Junction Compensator

ii

NOTES

1

SECTION 1 INTRODUCTION

1.1 GENERAL DESCRIPTION

The OMEGA-CJ is a portable battery-powered automatic cold
junction compensator for use in thermocouple circuits. It provides
the physical and electrical equivalents of an ice bath reference
thermocouple at 0°C or 32°F.

Thermocouples can be plugged directly into the OMEGA-CJ. A
quick disconnect male plug and output jack with banana plugs are
provided for connecting the CJ to potentiometers as well as to
meters and recorders of high input impedance.

1.2 FEATURES

• High reliability - solid state circuitry with self contained battery

• Rugged construction

• Color coded thermocouple calibration

• Instantaneous warm-up

• High Stability - better than ± 0.2°C at any stabilized temperature
over its full +10° to 50°C range

• Extreme versatility - unit can be plugged directly into a
thermocouple or into a jack panel.

• Long battery life - 1500 hours or longer depending on
calibration.

2

SECTION 2 UNPACKING

Remove the Packing List and verify that you have received all
equipment. If you have any questions about the shipment, please
call OMEGA Customer Service Department at
1-800-622-2378 or [phone].

When you receive the shipment, inspect the container and
equipment for any signs of damage. Note any evidence of rough
handling in transit. Immediately report any damage to the
shipping agent.

The carrier will not honor any claims unless all shipping material
is saved for their examination. After examining and removing
contents, save packing material and carton in the event
reshipment is necessary.

SECTION 3 OPERATION

3.1 OPERATING PROCEDURE

The OMEGA-CJ comes complete with quick-disconnect male plug
and output jack with banana plugs for connecting to
potentiometers, meters and recorders of high impedance.
Thermocouples can be plugged directly into the OMEGA-CJ.

NOTE

3

Operation is instant; the OMEGA-CJ’s solid-state design requires
no warm-up.

1. Connect output to OMEGA-CJ (TO INSTRUMENT) to readout
instrument. Copper wire extension leads must be used.

2. Connect thermocouple to other end of OMEGA-CJ (TO
THERMOCOUPLE). If thermocouple probe is not directly coupled to
OMEGA-CJ, it is necessary to use thermocouple extension wires
from the thermocouple to the OMEGA-CJ.

3. Move ON-OFF slide switch to ON to energize unit.

4. The readout instrument will not indicate the actually temperature,
unaffected by ambient temperature changes.

OMEGA-CJ has an internal resistance of up to 250 ohms,
depending on calibration; therefore, readout instruments of high
input resistance (impedance) must be used to minimize errors.
Following use, always move ON-OFF slide switch to OFF to
conserve the battery.

NOTE

4

3.2 BATTERY REPLACEMENT

3.2.1 Battery Life

The self-contained battery is a mercury cell - 1.35V Mallory
RM401R, or equivalent. Design life in continuous operation is as
follows:

Calibration Approximate Life

Chromel-Alumel 3000
Iron-Constantan 1500
Copper-Constantan 3800
Chromel-Constantan 1800
Pt/10% Rh-Pt 7800
Pt/13% Rh-Pt 7800
W-W/26% Re 5000
W/5% Re-W/26% Re 5000
W/3% Re-W/25% Re 5000

(hours)

5

3.2.2 Replacing the Battery

The indicator on the face of the OMEGA-CJ, energized by
depressing the BAT TEST push button, indicates when the battery
replacement is necessary. The battery should be replaced when the
indicator becomes dim.

To replace the battery, remove the cover plate by unscrewing
the single flathead screw and snap out the battery. Follow
correct polarity when installing the replacement battery.

6

Figure 4-1. Wiring Diagram

As the ambient temperature surrounding the cold junction varies, a
thermally generated voltage appears and produces an “error”.
However, an equal and opposite voltage produced by the bridge is
automatically introduced in series with the “error” voltage,
canceling the “error”. This maintains the reference temperature
over a wide ambient temperature range with a high degree of
accuracy.

By integrating copper leads with the cold junction, the
thermocouple material itself is not connected to the input terminals
of the measurement instrument, thereby eliminating secondary
errors.

7

SECTION 5 CALIBRATION

1. Remove the cover plate by unscrewing the single flathead screw
located on the back of the unit (see Figure 5-1).

Figure 5-1. OMEGA-CJ

2. Connect CJ to the thermocouple probe and readout instrument.

3. Place the thermocouple probe into an icebath and wait about 10
minutes for system to stabilize.

4. Adjust the ZERO POTENTIOMETER (located on the printed circuit
board inside the CJ) until the readout instrument shows “0” (zero).

5. Replace cover plate and secure with screw.

8

SECTION 6 SPECIFICATIONS

Reference Temperature Setting: 0°C or 32°F

Compensation Accuracy: ±1⁄4°C at 25°C ambient setting

±1⁄2°C from 15° to 35°C ambient
±3⁄4°C at 10° to 50°C ambient

Storage Temperature: -25° to +75°C (without battery)

Internal Resistance (Impedance): less than 250 ohms

Calibrations Available: Chromega

®

-Alomega

TM

Iron-Constantan
Copper-Constantan
CHROMEGA-Constantan
Pt/10% Rh-Pt
Pt/13% Rh-Pt
W-W/26% Re
W/5% Re-W/26% Re
W/3% Re-W/25% Re

Battery: 1.35V Mallory mercury cell

(RM401R)

Dimensions (H x L W): 1

3

⁄4" x 43⁄16" x 3⁄4"

(44.45 x 106.36 x 19.05 mm)

Weight: 12 oz (342.0 g)

9

NOTES

10

NOTES

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 Or de r n umb er t o c over 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.

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 2009 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied, reproduced, translated, or

reduced to any electronic medium or machine-readable form, in whole or in part, without the prior written consent of OMEGA ENGINEERING, INC.

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. OMEGA’s 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; 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.

RETURN REQUESTS / INQUIRIES

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.

TEMPERATURE

䡺⻬

Thermocouple, RTD & Thermistor
Probes, Connectors, Panels & Assemblies

䡺⻬

Wire: Thermocouple, RTD & Thermistor

䡺⻬

Calibrators & Ice Point References

䡺⻬

Recorders, Controllers & Process Monitors

䡺⻬

Infrared Pyrometers

PRESSURE, STRAIN
AND FORCE

䡺⻬

Transducers & Strain Gages

䡺⻬

Load Cells & Pressure Gages

䡺⻬

Displacement Transducers

䡺⻬

Instrumentation & Accessories

FLOW/LEVEL

䡺⻬

Rotameters, Gas Mass Flowmeters
& Flow Computers

䡺⻬

Air Velocity Indicators

䡺⻬

Turbine/Paddlewheel Systems

䡺⻬

Totalizers & Batch Controllers

pH/CONDUCTIVITY

䡺⻬

pH Electrodes, Testers & Accessories

䡺⻬

Benchtop/Laboratory Meters

䡺⻬

Controllers, Calibrators, Simulators
& Pumps

䡺⻬

Industrial pH & Conductivity Equipment

DATA ACQUISITION

䡺⻬

Data Acquisition &
Engineering Software

䡺⻬

Communications-Based
Acquisition Systems

䡺⻬

Plug-in Cards for Apple, IBM
& Compatibles

䡺⻬

Data Logging Systems

䡺⻬

Recorders, Printers & Plotters

HEATERS

䡺⻬

Heating Cable

䡺⻬

Cartridge & Strip Heaters

䡺⻬

Immersion & Band Heaters

䡺⻬

Flexible Heaters

䡺⻬

Laboratory Heaters

ENVIRONMENTAL
MONITORING AND CONTROL

䡺⻬

Metering & Control Instrumentation

䡺⻬

Refractometers

䡺⻬

Pumps & Tubing

䡺⻬

Air, Soil & Water Monitors

䡺⻬

Industrial Water & Wastewater
Treatment

䡺⻬

pH, Conductivity & Dissolved
Oxygen Instruments

Where Do I Find Everything I Need for

Process Measurement and Control?

OMEGA…Of Course!

Shop online at omega.com

SM

M0084/1002