What is a measuring transducer – principle of operation and application

A measurement transducer is an industrial device that allows the conversion of a measurement signal from a sensor into an output signal in analog or digital form. Its main purpose is to enable controllers and industrial automation systems to read measured values such as temperature, pressure, liquid level, or flow. The measurement transducer allows the electrical signal from the sensor to be processed in a way defined by the design and application requirements.

Transducers are used wherever it is necessary to monitor technological processes with a certain accuracy, and the measurement result must be sent to a PLC controller, display, or monitoring system.

Principle of operation of the transducer

The principle of operation of a measurement transducer is based on converting the input signal from the sensor into a standard output signal. The input signal can be voltage, current, or represented by resistance changes, as in the case of PT100 temperature sensors.

Analog transducers convert the input signal into a voltage (0–10 V) or current (4–20 mA, 0–20 mA) form, which allows the measured values to be transmitted over longer distances without significant signal loss. Digital transducers generate a digital signal that can be transmitted via interfaces such as RS-485, Modbus RTU, or other communication protocols.

Types of measurement transducers

Depending on the application, transducers can be divided into different categories:

• Temperature transducers – convert the signal from a temperature sensor (thermocouple, PT100) into a standard analog or digital signal.
• Pressure transducers – convert gas or liquid pressure into an electrical signal proportional to the pressure value.
• Liquid level and flow transducers – allow monitoring of the amount of liquid or its flow in industrial systems.
• Ultrasonic transducers – use ultrasonic waves to measure distance or liquid level.

Each of these types can have an analog output (0–10 V, 4–20 mA) or digital output (Modbus, RS485), and in some cases, transducers offer galvanic isolation to protect the system from electrical interference.

Temperature transducer – example of application

A temperature transducer is one of the most commonly used transducers in industrial automation. For example, measuring the temperature in an industrial boiler requires the signal from a PT100 temperature sensor to be converted into a 4–20 mA analog signal. The PLC controller reads the current value and can then control heating elements, fans, or control valves.

By using a measurement transducer, it is possible to precisely monitor ambient temperature and the technological process, which increases the safety and efficiency of the industrial automation system.

Analog and digital signals

Measurement transducers can operate in analog or digital mode. The analog signal, most often voltage (0–10 V) or current (4–20 mA), is proportional to the measured value and transmitted to the analog inputs of a controller or recorder.

The digital signal allows data transmission with greater resistance to interference and may contain additional information, such as the sensor identifier or device diagnostics. A digital interface, e.g., Modbus RTU over RS485, allows connecting multiple transducers to a single controller, increasing system flexibility.

Galvanic isolation and protection against interference

In industrial conditions, measurement transducers often offer galvanic isolation between input and output, which protects control systems against surges and interference. Galvanic isolation also allows signal transmission over long distances without the risk of damaging the controller.

Applications in industrial automation

Measurement transducers are used in various industrial automation systems where precise monitoring of technological processes is necessary. They can work with PLC controllers, SCADA systems, displays, or communication modules.

Transducers allow control of values such as temperature, pressure, flow, liquid level, voltage, or electric current, and the measurement result can be transmitted analogously or digitally. This ensures that industrial devices operate more safely, reliably, and energy-efficiently.

Interface transducers and signal standards

Some measurement transducers serve as interface devices, converting the sensor signal into a standard analog or digital signal. This enables integration with different types of controllers and monitoring systems. A standard analog signal may have a range of 0–10 V, 0–20 mA, or 4–20 mA, allowing connection of the transducer to a wide range of devices.

Types of transducers depending on input signal

• Transducers for voltage signals (mV, V) – used in analog systems.
• Transducers for current signals (4–20 mA, 0–20 mA) – resistant to interference and used for long-distance transmission.
• Analog-to-digital converters (ADC) – convert analog signals into digital signals for further digital transmission.
• Interface transducers Modbus/RS485 – enable communication with multiple devices in an industrial network.

Summary

A measurement transducer is an essential device in industrial automation systems, allowing the conversion of a sensor signal into a standard analog or digital signal. It enables PLC controllers, displays, and monitoring systems to accurately read measured values. Temperature, pressure, flow, and liquid level transducers are fundamental for controlling technological processes. Using measurement transducers enables efficient signal transmission, galvanic isolation, protection against interference, and optimization of industrial processes.

We invite you to explore our offer and discover solutions tailored to your needs in the field of measurement transducers. Contact us to learn more about the measurement possibilities in your system.