What is RTD OR PT100

What is RTD Sensor  / PT100 v/s P1000 

All production industries widely used RTD is to measure the temperature. PT100 and PT1000 are the most commonly used Platinum temperature sensors  These are the same characteristics but the nominal resistance is different.  

PT indicates the sensor made upon platinum material and 100 or 1000 indicate sensor has minimum resistance at 0-degree celcius. basic principles of PTC are very simple, to have a known resistance wire it will increase resistance with respect to temperature.

Let see the PT100 and PT1000 temperature sensor.  100-ohm and 1000-ohm resistance in 0-degree temperature respectively. The resistance variation function of temperature is 0.39ohm/celsius and 3.9ohm/celsius. That is Resistance of PT100 and PT1000 at 1-degree temperature are 100.39 ohms, 1003.9 ohms respectively.

 RTD is available in three types

1. 2- Wire RTD
2. 3- Wire RTD
3. 4- Wire RTD

2-Wire RTD:- Two-wire RTD basic form of designing. simple two lead connected across RTD element.net result some error occur in the result. commonly used for measuring the least accurate value.

Re - Element resistance.

R1 & R2- Lead resistance.

Ro - Output value

Ro = Re + R1 + R2

3-Wire  RTD:- Three-wire RTD widely used in process industries. Because it will provide moderate accurate value. 

In this model have three identical leads to connect sensing element R1=R2=R3 by measuring lead connecting in between R1&R2 

So Ro = (R1+R2+Re)-(R2+R3)

4-Wire RTD:- Four-wire RTD mostly used in the laboratory. the configuration is more complex, expensive and time-consuming but it will provide the most accurate measurement. 4 wire RTD has 4 identical leads to connect sensing elements. each terminal of the sensing element has two leads. it will cancel each other.

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