Inst ToolsInst ToolsInst Tools
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Search
  • Books
  • Software
  • Projects
  • Process
  • Tools
  • Basics
  • Formula
  • Power Plant
  • Root Cause Analysis
  • Electrical Basics
  • Animation
  • Standards
  • 4-20 mA Course
  • Siemens PLC Course
Reading: Thermocouple Details
Share
Font ResizerAa
Inst ToolsInst Tools
Font ResizerAa
  • Courses
  • Design
  • PLC
  • Interview
  • Control System
Search
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > Temperature Measurement > Thermocouple Details

Thermocouple Details

Learn all the details of temperature measuring element thermocouple sensor wiring, standard, tolerance, and troubleshooting.

Last updated: September 19, 2020 11:16 am
Editorial Staff
Temperature Measurement
2 Comments
Share
4 Min Read
SHARE

Thermocouple wiring

  • The thermocouple extension wire should meet the requirements of ISA/ANSI MC96.1 or IEC-60584.
  • Thermocouple signals are low-level signals that should be properly shielded and grounded to prevent noise interference with the signal.
  • Insulated hot junctions shall have an insulation resistance to ground of 50 megohms minimum at ambient temperature and 2 megohms minimum at 4508C (8508F).
  • Terminals within the head shall be clearly marked ‘+’, ‘-’, ‘ground’, as appropriate.
  • The multi circuits within heads shall be clearly identified
  • Check that the polarity and continuity of the lead wires are consistent through all the junction boxes from the thermocouple head to the control center

Grounded Thermocouple

  • For grounded thermocouples, check that the shield wire is terminated at the grounded thermocouple head in accordance with the manufacturer’s instructions and not at the shield connection on the control center or instrument terminals

Grounded and Ungrounded Thermocouples

Contents
Thermocouple wiringGrounded ThermocoupleUn-Grounded ThermocoupleThermocouple Color CodesThermocouple ToleranceThermocouple StandardThermocouple Troubleshooting

Un-Grounded Thermocouple

  • For ungrounded thermocouples, check that the shield wire is terminated in the control room.
  • Grounding of the shield at more than one location should be avoided. Individual shielding of multi-pair cables, in addition to an overall shield, can help maintain the shield circuit at the individual ground potential all the way back to the receiver location.

Notes

  • Thermocouples can be tested by immersion in a temperature bath and the output measured using a Portable Calibrator.
  • Thermocouple selection is done based on temperature range and accuracy as per ISA/ANSI/IEC standards.

Thermocouple Color Codes

Thermocouple Color Code as per IEC and ANSI Standards

Image Courtesy: Omega

Thermocouple Tolerance

1) Tolerance is referred to as the maximum allowable deviation between hot junction temperature and the temperature derived from the EMF table.

2) ASTM temperature is C or % value for the measured temperature, which is greater.

3) | t | is the measuring temperature indicated by the temperature irrelevant to the symbol + or -.

4) Class 1, 2, or 3 conforms to the old JIS Class 0.4, 0.75 or 1.5, respectively.

5) JIS Standard is identical with IEC, BS or DIN Standard except for a part.

6) The tolerance of JISC1605 and JISC1602 is completely the same.

7) ASTM Standard is same as the old ANSI Standard.

8) Tolerances given in this table apply only to new wire as delivered to the user and do not allow for changes in characteristics with use. (ASTM E230)

9) The standard tolerances shown do not apply to Type E mineral-insulated, metal-sheathed (MIMS) thermocouples and thermocouple cables as described in Specifications E608/E608M and E585/E585M. The standard tolerances for MIMS Type E constructions are the greater of 2.2°C or 0.75 % from 0 to 870°C and the greater of 2.2°C or 2 % from -200 to 0°C.

Thermocouple Tolerance

Thermocouple Standard

Thermocouple Standard

Thermocouple Troubleshooting

Troubleshooting for Thermocouples

Reference: okazaki

Author: Mohammed Khaleel

Read Next:

  • RTD Construction
  • RTD Temperature Error
  • Thermocouple Applications
  • Thermocouple Construction
  • Terminate the Cable Shield
Don't Miss Our Updates
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Invalid email address
You've successfully subscribed !

Continue Reading

Types of Thermowells
Basic Temperature Sensors MCQ Questions Answers
Types of Thermocouple Measuring Junction
18 Temperature Sensors Fault Leads to Plant Shutdown
Basics of Thermocouples and RTD
Questions on Thermocouple and Pyrometer
Share This Article
Facebook Whatsapp Whatsapp LinkedIn Copy Link
Share
2 Comments
  • R JAGAN MOHAN RAO says:
    September 19, 2020 at 10:17 am

    A very good article, with lot of required information can be found at a place. Inclusion of thermocouple color code chart as per the IEC and ANSI standards may be considered for adding more fragrance to the article.

    Reply
  • Dave Bartran says:
    September 21, 2020 at 2:21 am

    You may find the following site of interest when dealing with thermowells and temperature response times,

    https://www.thermowellsoftware.com

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Stay Connected

128.3kFollowersLike
69.1kFollowersFollow
210kSubscribersSubscribe
38kFollowersFollow

Categories

Explore More

Pyrometers Handbook
Thermowell Design Guidelines
Seebeck Effect Theory
How to Install Thermowell on an Elbow?
What is RTD Accuracy ?
Resistance Temperature Detectors Working Principle
RTD Calculator : Calculate Temperature from Resistance
Why 4 wire RTD Measurement Accuracy is better than 2 and 3 wire RTD?

Keep Learning

Thermocouple Calibration

Thermocouple Calibration

Thermocouples

Important Factors for Thermocouple Selection

Thermowell Immersion Length

Thermowell Insertion and Immersion Length

How to calculate Thermocouple Temperature by measuring the output millivoltage

Thermowell Wake Frequency Calculation

Thermowell Wake Frequency Calculation

RTD Calibration

RTD Calibration

4-wire RTD Bridge Circuit

Why we use Wheatstone bridge in RTD?

Head Mount Temperature Transmitter

What is a Head Mount Temperature Transmitter? – Advantages

Learn More

Guide to vibration severity per ISO 10816

Importance of Vibration Measurement

Useful Trigonometry Website for Students Math Help

The Impact of Knowledge Management Platforms on Business Operations

Capacitors Connected in Parallel

Series and Parallel Capacitors

Schneider Electric Modicon M340 PAC

PLC vs PAC – Understanding the Key Differences and Similarities

Bipolar Junction Transistor Construction

Bipolar Junction Transistor Construction

List of 100 Questions Related to Distributed Control Systems (DCS)

List of 100 Distributed Control Systems Questions (DCS)

Digital Electronics Multiple Choice Questions

Flip Flops Objective Questions – Part 1

PLC Based Metro Automation Project

PLC based Metro Automation Project

Menu

  • About
  • Privacy Policy
  • Copyright

Quick Links

  • Learn PLC
  • Helping Hand
  • Part Time Job

YouTube Subscribe

Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Welcome Back!

Sign in to your account

Username or Email Address
Password

Lost your password?