- #1
Resistance Temperature Detectors
- Thread starter pinkcashmere
- Start date
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SUMMARY
This discussion focuses on the functionality of three-wire and four-wire Resistance Temperature Detectors (RTDs) and how lead resistances influence voltage output. The voltage output formula provided is V_o = (R_3 V_s) / (R_2 + R_3) - (R_4 V_s) / (R_1 + R_4). The purpose of Lead C in a three-wire RTD is clarified through the concepts of Kelvin Contacts and the Kelvin Bridge, which are essential for minimizing measurement errors caused by lead resistance. Understanding these principles is crucial for accurate temperature measurements using RTDs.
PREREQUISITES- Understanding of Resistance Temperature Detectors (RTDs)
- Knowledge of electrical circuit theory
- Familiarity with Kelvin Contacts
- Basic grasp of the Kelvin Bridge concept
- Study the mathematical derivation of voltage output in three-wire and four-wire RTD circuits
- Research the principles of Kelvin Contacts and their application in temperature measurement
- Explore the design and functionality of the Kelvin Bridge
- Investigate methods to minimize lead resistance in RTD applications
Electrical engineers, instrumentation specialists, and anyone involved in temperature measurement and sensor accuracy will benefit from this discussion.
- #2
meBigGuy
Gold Member
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- 406
First you need to understand Kelvin Contacts:
https://en.wikipedia.org/wiki/Four-terminal_sensing
Then,the Kelvin Bridge.
https://en.wikipedia.org/wiki/Kelvin_bridge
Then either you will have your answers or more questions.
The whole goal is to eliminate errors caused by measuring the voltage drop across the current carrying wires that are feeding the sensors.
Maybe you understand that already, but I think you just need to work through the math of the two circuits to see how the errors cancel.
https://en.wikipedia.org/wiki/Four-terminal_sensing
Then,the Kelvin Bridge.
https://en.wikipedia.org/wiki/Kelvin_bridge
Then either you will have your answers or more questions.
The whole goal is to eliminate errors caused by measuring the voltage drop across the current carrying wires that are feeding the sensors.
Maybe you understand that already, but I think you just need to work through the math of the two circuits to see how the errors cancel.
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