Which is more accurate, a RTD or a thermocouple?

Thermal resistors and thermocouples have their own advantages and disadvantages in temperature measurement within different temperature ranges. Which one is more accurate depends on the specific application scenario.

I. Thermal resistance
Thermistors achieve the purpose of temperature measurement by taking advantage of the principle that resistance changes with temperature. Common types of thermal resistors include platinum thermal resistors and molybdenum thermal resistors, etc. They all calculate temperature by measuring changes in resistance.

Advantages:

1. High precision: The precision of thermal resistors is higher than that of thermocouples, reaching an accuracy of 0.1℃.

2. Good stability: As the thermal resistor itself is a resistive component and does not require the introduction of an auxiliary power supply, its accuracy changes relatively little within a short period of time.

Disadvantage:

1. Slower response speed: Due to the complex structure of the thermal resistor, its response speed is slower than that of the thermocouple.

2. Narrow applicable temperature range: The applicable temperature range of thermal resistors is generally between -200℃ and +800℃.

Ii. Thermocouple
A thermocouple measures temperature by utilizing the electromotive force generated from the thermoelectric potentials of two different metals. Common thermocouples include K-type, S-type, R-type, etc., and they have different application advantages within different temperature ranges.

Advantages:

1. Fast response speed: The structure of thermocouples is simple, so their response speed is much faster than that of thermal resistors.

2. Applicable to a wide temperature range: Thermocouples have a very wide range of applications, from -200℃ to +1800℃.

Disadvantage:

1. Poor stability: The measurement accuracy of thermocouples is affected by many factors, such as the selection of metal materials and the impact of temperature changes on metal materials, so its measurement accuracy is relatively low.

2. Low precision: The precision requirement for thermocouples is generally around ±1℃.

Iii. Which one is more accurate?
Thermocouples and thermal resistors each have their own advantages and disadvantages in measurement, so which one is more accurate depends on the specific application scenario. Generally speaking, for scenarios where temperature changes slowly and high measurement accuracy is required, thermal resistors are a better choice. For scenarios with rapid temperature changes, a wide applicable temperature range, and low requirements for measurement accuracy, thermocouples are a better choice.

【 Conclusion 】 To sum up, both thermal resistors and thermocouples have their own advantages and disadvantages, and the choice should be based on the specific application scenario.