Whatever the type of industry, Temperature always plays an important role. Some processes needs stable temperature for proper functioning, A little variation can produce an alteration in final product.
For better accuracy, PT-100 sensors been used in industries for temperature measurement. This post is all about PT-100.
PT-100
PT-100 sensors are type of RTD. And RTD stands for ‘Resistance temperature detector‘. These sensors are used to measure temperature. As name describes, These sensors follows the stable temperature & resistance relation Whose resistance value increases as temperature increases. These sensors are available in 3 & 4 wires & having a measuring range of -200°C to 500°C.
WORKING OF PT-100 TEMPERATURE SENSOR
These sensors mainly contains metallic element such as platinum Which Enclosed inside tube of glass or metal. Enclosed metallic element follows temperature-resistance relation in direct proportion. It’s resistance value increases as temperature increases. For resistance measurement, Wires are connected to this metallic element.
Sensors wires are further connected to microcontroller through thin wires. Microcontroller continuously monitors the resistance value. Particular temperature has fixed resistance value. Such that; At 100°C; resistance valve will be 125 ohm While at 0°C, value will be 100 ohm.
resistance & temperature proportion data is saved in microcontroller. As per according to stored program & current running resistance value, Controller displays the temperature.
An image of bisected PT-100 shown below Which shows a micro platinum element connected to three wires.
A Schematic diagram of PT-100 element below; Shows the connection to the sensor. Red wire is connected to one node while remaining 2 wires are connected to another node.
WHY DO IT’S BEEN CALLED, PT-100 ?
PT-100, ‘PT‘ is the symbol which represents ‘platinum‘ While ‘100‘ represents its resistance value at ‘0°C‘. As temperature increases its resistance value increases. At 100°C resistance valve becomes 125 ohm.
There are Another RTD series which is known as PT-1000. PT-1000 sensors are widely used for greater accuracy, More than PT-100. In PT-1000, 1000 is the resistance value at a temperature of 0°C.
COMPOSITION OF PT-100
The main metallic element platinum is enclosed inside the heavy metallic or glass hollow pipe. This hollow pipe provides mechanical strength So that Sensor easily immersed inside the material without getting damaged or deteriorated.
For reaction elimination, element inside the chamber is filled with “magnesium oxide”. Magnesium oxide is good dielectric substance Which is having a good thermal conductivity.
An image of bisected PT-100 sensor is shown below. Which shows the Platinum Element & magnesium oxide are been taken out from the tube of PT-100.
DIFFERENT SHAPES & SIZES OF PT-100
PT-100 Sensors are available in two types :
- Head type PT-100: These type PT-100 sensor contains a terminal block on its head.
- Without head type PT-100: These type of sensors contains a long wire rather than terminals.
These types head & without head are further available in multiple shapes & sizes. Shape & Size includes its diameter & length.
WHY DO PT-100 SENSORS HAS THREE WIRES ?
For resistance measurement, Just 2 wires needed but this sensors is available in 3 wires. Pt-100 sensors are widely used for its accuracy & Accuracy is the reason behind the 3rd wire !
In PT-100, temperature completely depend upon resistance . A little variation in resistance can produce the alteration in the reading. Temperature sensors are connected to temperature meter through wires, Total length of wires can go up to 100 meters.
Resistance varies directly proportional to the length of the conductor; as length increases resistance increases.
Sensor wire length can produce an error in final reading. To remove this length resistance , 3rd wire is being used.
Circuit Diagram shown below depicts PT-100 Sensor connected to temperature meter. Temperature Meter has 3 terminals A,B&C While PT-100 is also having 3 Terminals A1, B1 & C1.
Temperature Meter measures 2 resistance here, One from A terminal to B & second; from B to C. resistance between terminals A,B contains total resistance Which includes PT-100 element resistance & Total Wire resistance . resistance between B,C contains only resistance of wires. By subtracting the wire resistance from the total resistance , A real element resistance can be calculated ! (Hope, You got the answer. If you have any doubt please print a comment down below:)
SUMMARY
- PT-100 sensors are type of RTD. And RTD stands for ‘Resistance temperature detector‘.
- These sensors are available in 3 & 4 wires.
- Measuring range of -200°C to 500°C.
- These sensors mainly contains metallic element such as platinum Which Enclosed inside the tube of glass & metal.
- Metallic element in PT-100, follows temperature-resistance relation in direct proportion. It’s resistance value increases as temperature increases.
- PT-100, ‘PT‘ is the symbol which represents ‘platinum‘ While ‘100‘ represents its resistance value at ‘0°C‘.
- The main metallic element platinum is enclosed inside the heavy metallic or glass hollow pipe. This hollow pipe provides mechanical strength So that Sensor easily get immersed inside the material without getting damaged or deteriorated.
- For reaction elimination, element inside the chamber is filled with magnesium oxide. Magnesium oxide is good dielectric substance Which is having a good thermal conductivity.
- PT-100 Sensors are available in two types ‘head’ & ‘without head’. These types are further available in multiple shapes & sizes.
- To measure the resistance, Just 2 wires needed but this sensors is available in 3 wires. Pt-100 sensors are widely used for its accuracy & Accuracy is the reason behind the 3rd wire.