🔧 What Is a Thermocouple?

A thermocouple is a type of temperature sensor that converts thermal energy into electrical energy using the Seebeck effect. It's commonly used in various industrial, scientific, and commercial applications to measure temperature.

Thermocouple Structure

A thermocouple consists of two different metals or alloys joined together at one end, forming a "junction". When the temperature at this junction differs from the temperature at the other ends (called the reference ends), a voltage (called thermoelectric EMF) is generated.

Common Materials

• Type K (Chromel–Alumel): General purpose
• Type J (Iron–Constantan): Lower temperature
• Type T (Copper–Constantan): Accurate for low temperatures
• Type E, N, R, S, B: Specialized industrial use

⚙️ How Does a Thermocouple Work?

1. Seebeck Effect

When two dissimilar metals are joined and the junctions are at different temperatures, a voltage is generated. This voltage correlates with the temperature difference.

2. Measuring Temperature

• Hot Junction: Placed where temperature is measured.
• Cold Junction (Reference Junction): Kept at a known temperature (often electronically compensated in modern instruments).

The thermocouple outputs a small voltage (in millivolts), which is read and converted to temperature by a thermocouple thermometer or controller.

📏 Key Characteristics

🧪 Applications

• Industrial furnaces and kilns
• Engine and exhaust systems
• Food processing
• HVAC systems
• Scientific experiments

📌 Summary

A thermocouple is a simple, rugged, and cost-effective way to measure temperature, especially in demanding environments. It works on the principle of the Seebeck effect, where different metals generate a voltage in response to temperature differences.