Instrumentation

Temperature controllers come in various types to suit industrial and laboratory needs. The most common are ON/OFF controllers, ideal for simple applications; PID controllers, offering precise proportional, integral, and derivative control; and programmable controllers, designed for complex multi-step processes. Case sizes typically follow DIN standards, ranging from compact 1/16 DIN (48 × 48 mm) units for space-limited panels to larger 1/8 DIN (48 × 96 mm)  and 1/4 DIN (96 × 96 mm) models for enhanced visibility and operation. Control options include relay, SSR drive, and analog outputs, allowing integration with diverse heating or cooling systems. Selecting the right controller depends on application complexity, required accuracy, and available panel space.

ON/OFF control is the simplest form of temperature regulation, switching output fully on or off depending on the setpoint. It is cost-effective and suitable for non-critical applications but may cause temperature oscillations due to its binary operation. In contrast, PID control (Proportional, Integral, Derivative) provides continuous and precise regulation by adjusting output smoothly based on error, accumulated offset, and rate of change. This results in stable temperature control with minimal overshoot, ideal for processes requiring high accuracy and consistency. While ON/OFF controllers are straightforward and reliable for basic heating or cooling, PID controllers deliver advanced performance, making them the preferred choice for demanding industrial and laboratory environments.

A signal conditioner is an essential device that converts and optimizes sensor signals for accurate measurement and control. In temperature applications, thermocouples and RTDs generate low-level, often non-linear signals that can be prone to noise and interference. A signal conditioner amplifies these signals, applies linearization, and provides isolation to ensure reliable data transmission to controllers, PLCs, or monitoring systems. For thermocouples, it compensates for cold junction errors, while for RTDs it delivers precise resistance-to-voltage conversion. Outputs are typically standardized to 4–20 mA, 0–10 V, or digital formats, making integration seamless across industrial automation platforms. By enhancing accuracy and stability, signal conditioners play a critical role in achieving consistent temperature monitoring and process control.

Data logging and data acquisition serve different roles in temperature measurement systems. Data logging involves the continuous recording and storage of temperature readings over time, typically using stand-alone devices with onboard memory. This is ideal for applications such as cold chain monitoring, environmental testing, or long-term process tracking, where historical records are critical. In contrast, data acquisition focuses on the real-time collection and analysis of temperature signals, often using multi-channel systems connected to PCs, PLCs, or SCADA platforms. It enables immediate processing, visualisation, and control, making it suitable for dynamic or complex processes requiring instant feedback. In short, data logging ensures reliable long-term record keeping, while data acquisition delivers fast, actionable insights for advanced temperature control and system optimisation.

Infrared thermometers work by detecting infrared radiation, a type of heat energy emitted by all objects. Every object above absolute zero gives off infrared radiation proportional to its temperature. The thermometer’s lens focuses this radiation onto a sensor, called a thermopile, which absorbs the energy and converts it into an electrical signal. The device’s microprocessor then translates this signal into a temperature reading, displayed in degrees Celsius or Fahrenheit. Because infrared thermometers measure surface temperature without physical contact, they are ideal for situations where objects are moving, very hot, hazardous, or otherwise difficult to reach, ensuring safe and fast measurements.

Emissivity is a measure of how efficiently an object emits infrared radiation compared to a perfect blackbody, which has an emissivity value of 1. It ranges from 0 to 1, where higher values indicate that a surface emits more infrared energy. Materials like matte black paint have high emissivity, while shiny metals have low emissivity because they reflect more radiation than they emit. Emissivity plays an important role in accurate temperature measurements using infrared thermometers or thermal cameras. If the emissivity of a surface is not properly accounted for, the temperature reading can be significantly higher or lower than the true value.