Resistance Temperature Detectors (RTDs): An Overview

Resistance thermometers, commonly known as Resistance Temperature Detectors (RTDs), are highly accurate and reliable sensors used to measure Temperature by correlating the resistance of the RTD element with Temperature. They are widely used in applications where precision and stability are critical. Unlike thermocouples, RTDs operate based on the predictable change in electrical resistance of certain metals—most notably platinum—with Temperature.

RTDs are valued for their excellent repeatability, long-term stability, and accurate linear output over a broad Temperature range. They are commonly employed in laboratory, industrial, and commercial settings for Temperature monitoring and control, especially in processes requiring consistent and precise measurements.

Working Principle

The working principle of an RTD is rooted in the positive Temperature coefficient of electrical resistance exhibited by metals like platinum, nickel, or copper. As the Temperature increases, the resistance of the RTD element also increases in a known and repeatable manner.

An RTD element typically consists of a fine wire wrapped around a ceramic or glass core. The resistance is measured using a Wheatstone bridge or similar circuit, and the corresponding Temperature is derived based on standardized resistance-Temperature characteristics (such as the DIN EN 60751 standard for platinum RTDs).

Due to their stable and accurate behavior, RTDs are widely used where precise Temperature monitoring is essential, such as in power plants, refineries, chemical plants, and aerospace applications.

Model S2 – Manufactured by Ajmer Thermotech Pvt. Ltd.

Ajmer Thermotech Pvt. Ltd., an ISO 9001:2015 and CE certified company, manufactures and supplies the Model S2 RTD, designed with a compression fitting mounting style. This model is engineered for secure, adjustable, and leak-resistant installation in process systems where precise positioning of the RTD sensor is essential.

The compression fitting design allows the sensor to be easily inserted and locked into place at the desired immersion depth without requiring threaded connections or welding. This flexibility is particularly beneficial in applications requiring regular maintenance, calibration, or repositioning.

Constructed using high-purity platinum sensing elements and robust sheath materials such as stainless steel, the Model S2 offers high accuracy, excellent thermal response, and long-term stability. It is available in 2-wire, 3-wire, and 4-wire configurations, and can be customized with various sheath diameters, lengths, tolerance classes, and lead wire options.

Ideal for laboratory, pharmaceutical, food processing, and general industrial use, the Model S2 provides reliable and repeatable Temperature measurement while offering convenient installation and maintenance through its versatile compression fitting design.