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: Components of RTD
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 > Components of RTD

Components of RTD

Last updated: September 26, 2019 8:06 pm
Editorial Staff
Temperature Measurement
No Comments
Share
6 Min Read
SHARE

Resistance Temperature Detector (RTD) is a temperature sensor which measures temperature using the principle that the resistance of a metal changes with temperature.

Contents
Components of RTDWhat’s PT100, PT500, PT1000RTD Advantages and Limitations2 wire, 3 wire or 4 wire RTDs?What are the common components of an RTD?

In practice, an electrical current is transmitted through a piece of metal (the RTD element or resistor) located in proximity to the area where temperature is to be measured.

The resistance value of the RTD element is then measured by an instrument. This resistance value is then correlated to temperature based upon the known resistance characteristics of the RTD element.

Components of RTD

What is an RTD

Platinum resistance thermometers are electrical thermometers which make use of the variation of resistance of high-purity platinum wire with temperature. This variation is predictable, enabling accurate measurements to be performed.

They are sensitive and, with sophisticated equipment, measurements can routinely be made to better than a thousandth part of 1°C. The temperature coefficient defines how much the resistance will change in temperature and has units of ohms / ºC.

The greater the temperature coefficient, the more the resistance will change for a given change in temperature. Similarly, as the temperature of the RTD resistance element increases, the electrical resistance, measured in ohms (Ω), increases. RTD elements are commonly specified according to their resistance in ohms at zero degrees Celsius (0° C).

Read: Interview Questions on RTD

The most common RTD specification is 100 Ω, which means that at 0° C the RTD element should demonstrate 100 Ω of resistance.

RTD’s are generally quite linear, however, the temperature coefficient does vary over the range of operation. As an indication, the temperature coefficient of Platinum is averaged at 0.00385 over the range of 0 to 100 ºC., but varies about 2% over the same range.

What’s PT100, PT500, PT1000

They are all types of RTD (Resistance Temperature Detector) sensors that are made from Platinum. The Pt100 sensor has a resistance of 100 ohms at 0°C and is by far the most common type of RTD sensor.

The Pt500 sensor has a resistance of 500 ohms at 0°C and the Pt1000 has 1000 ohms resistance at 0°C.

These sensors are normally fitted into some type of protective sheath or mounting to form a probe, and these are commonly referred to as PRT (Platinum Resistance Thermometer) or RTD probes.

RTD Advantages and Limitations

RTD is one of the most accurate temperature sensors. Not only does it provide good accuracy, but it also provides excellent stability and repeatability. RTDs are also relatively immune to electrical noise and therefore well suited for temperature measurement in industrial environments, especially around motors, generators, and other high voltage equipment.

RTDs in industrial applications are rarely used above 660 °C. At temperatures above 660°C it becomes increasingly difficult to prevent the platinum from becoming contaminated by impurities from the metal sheath of the thermometer.

2 wire, 3 wire or 4 wire RTDs?

A simple rule of thumb is that the more wires an RTD has the more accurate it is. Explanation about RTD wiring configurations 2 wire, 3 wire, or 4 wire RTDs

Read Also

  • Equations of RTD’s
  • Temperature Error of RTD
  • Tolerance of RTD
  • Errors of RTD
  • RTD Lead Wire

What are the common components of an RTD?

RTD platinum resistance element:

This is the actual temperature sensing portion of the RTD. Elements range in length from 1/8″ to 3″. There are many options. The standard temperature coefficient is an alpha of .00385 and the standard resistance is 100 Ω at 0° C.

RTD Outside diameter:

The most common outside diameter is ¼” in the US or 6mm (.236″) for non-US applications. However, outside diameters range from .063″ to .500″

RTD Tubing Material:

316 Stainless steel is commonly used for assemblies up to 500° F. Above 500° F it is advisable to use Inconel 600.

RTD Process Connection:

Process connection fittings include all standard fittings used with thermocouples (i.e. compression, welded, spring-loaded, etc.).

RTD Wire Configuration:

RTDs are available in 2, 3 and 4 wire configuration. 3 wire configurations are the most common for industrial applications. Teflon and fiberglass are the standard wire insulation materials.

Teflon is moisture resistant and can be used up to 400° F. Fiberglass can be used up to 1000° F.

RTD cold end termination:

RTDs can terminate on the cold end with plugs, bare wires, terminal heads and any of the reference junctions common to thermocouples.

Reference – jms-se

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

RTD Calculator : Calculate Temperature from Resistance
Why have been limits imposed on the frequency ratio for thermowells?
Temperature Sensor Failure
Calibration of Temperature Sensor with Indicator
Bimetallic Thermometer
Thermocouple Questions and Answers
Share This Article
Facebook Whatsapp Whatsapp LinkedIn Copy Link
Share
Leave a Comment

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

Bridge Circuit Construction
Thermowell Installation near Critical Equipment
Temperature Switch Working Principle
Difference Between RTD, Thermocouple and Thermistor
Thermocouple Calibration
How to Install Thermowell on an Elbow?
Skin Type Thermocouple
Applications of Temperature Scanner

Keep Learning

Thermocouple Wiring Diagram

Basics of Thermocouples and RTD

Thermocouple Types

Types of Thermocouples

Temperature Sensors Questions

Questions on Thermocouple and Pyrometer

What is Temperature

What is Temperature ?

field-mounted thermocouple

Thermocouple Extension Wires

Laws of Thermocouples

Temperature Transmitter Foundation Fieldbus Configuration

Foundation Fieldbus Temperature Transmitter Configuration

Thermocouple Temperature Ranges

Thermocouple Temperature Range Questions and Answers

Learn More

Main Functions of a Multimeter

Interesting Multimeter Functions (And What They Really Do)

Gas Detectors Bump Testing

What is Bump Testing ?

Using Kirchhoff’s Voltage Law to find Current with one Source

Applying Kirchhoff’s Voltage Law

Direct Acting Actuators

Effect of Differential Pressure on Control Valve Lift

Cables Sheath Material

Instrument Cables Sheath Material

Circuit Diagram of Displacement Transducer

What is a Displacement Transducer? – Types and Advantages

Find the Fault in the Temperature Loop

Fault in the Temperature Loop

Why Circuit Breakers Don't Protect People?

Why Circuit Breakers Don’t Protect People?

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?