RTD Basics

 RTD stand for :-

R-Resistance 

T-Temperature 

D-Detector

RTD also known as Resistance Thermometer. RTD is a temperature sensor used to measure the Temperature of any industrial process.

Working Principle:

RTD works on principle that the electrical resistance of a  metal changes with change in Temperature. Whenever temperature of a metal increase, the it’s resistance also increase. 

RTD element is made of restive  material most likely Platinum. 

When ever  the temperature of a measuring element is changes its resistance will also increases linearly. The resistance change in RTD Element is directly propositional to  the change in temperature of RTD element.  

Why Platinum is used in RTD Elements

Platinum, Nickel or Copper may used in RTD element but he 

Platinum is the most commonly used material because 

Platinum has high accuracy, excellent  repeatability and also 

it is linear  over a wide range of temperature. These 

properties makes the Platinum best suitable material.

Most importantly the Platinum has large enough Resistance 

Temperature coefficient of  Resistance α (Alpha). Which mean more change in resistance with per degree change in Temperature.

There are three types of RTD available in Platinum Sensing Meterial

1. PT-100 :    RTD Output will be 100 Ohms on  0 °C .
2. PT-500 :    RTD Output will be 100 Ohms on  0 °C
3. PT-1000 :  RTD Output will be 100 Ohms on  0 °C