Four-wire configuration

The four-wire resistance thermometer configuration increases the accuracy and reliability of the resistance being measured: the resistance error due to lead wire resistance is zero. In the diagram above a standard two-terminal RTD is used with another pair of wires to form an additional loop that cancels out the lead resistance. The above Wheatstone bridge method uses a little more copper wire and is not a perfect solution. Below is a better configuration, four-wire Kelvin connection. It provides full cancellation of spurious effects; cable resistance of up to 15 Ω can be handled. 

Applications

Immersion sensors take the form of an SS tube and some type of process connection fitting. They are installed into the process with sufficient immersion length to ensure good contact with the process medium and reduce external influences.A variation of this style includes a separate thermowell that provides additional protection for the sensor.These styles are used to measure fluid or gas temperatures in pipes and tanks. Most sensors have the sensing element located at the tip of the stainless steel tube. An averaging style RTD however, can measure an average temperature of air in a large duct. This style of immersion RTD has the sensing element distributed along the entire probe length and provides an average temperature. Lengths range from 3 to 60 feet .

Quote requirements 

Pls inform the following thins when you inquire

1)Full series No, If you have

2) Application Scope (Petroleum industry, Chemical industry, Power Station, etc)

3)Required Temperature Range

4)Sensor Material or type(PtRh6,K,N,P,C etc)

5) Fixing or Installation Type (Movable Flange Type, Non Fixing type Thread type)

6) Thermowell Material and Diameter if needed(1Cr18Ni9Ti,16,20)

7) Insert Length

8) Accuracy Class(Thermocouple, Resistance thermometer AB)

9) Other Special Requirements