Thermik Gerätebau: Temperature monitoring with thermistors

Thermik Gerätebau: Temperature monitoring with thermistors

PTC thermistors are technical components that are used to monitor and control temperatures in a wide range of applications. PTC stands for “Positive Temperature Coefficient” and describes the property of the components to increase their electrical resistance with increasing temperatures. PTC thermistors from Thermik Gerätebau GmbH are used worldwide for overheating protection or temperature control. But how exactly does temperature monitoring with thermistors work – and what makes Thermik products so unique?

PTC thermistors are technical components that are used to monitor and control temperatures in a wide variety of applications

Thermik Gerätebau GmbH has been specialising in the regulation, control and monitoring of temperatures in electronic devices since 1968. The success story of the internationally renowned German medium-sized company began with a creative and ingenious idea from founder Peter Hofsaess.

With the W1000 thermal protectors, he solved the previously unresolved problem of current self-heating in bimetal switches – and laid the foundation for today’s global success of thermics with this first patented invention. Over the decades, the company expanded its product portfolio to include so-called thermistors. These small components, invisible to the end user and installed in household appliances, motors or heaters, monitor and regulate temperatures in electrically powered devices.

How a PTC thermistor works

Thermistors is a portmanteau word derived from the words “thermal” and “resistor”, meaning “thermal resistance”. A thermistor is therefore a thermally sensitive component whose electrical resistance changes with the prevailing ambient temperature. A distinction is made between two main types, NTC and PTC thermistors.

NTC thermistors operate with a negative temperature coefficient. The electrical resistance of these components decreases with increasing temperatures. In contrast, PTC thermistors work with a positive temperature coefficient: Here, the electrical resistance increases with rising temperatures. PTC thermistors are therefore particularly suitable for applications where overheating protection is required or as inrush current limiters in electronic circuits.

PTC thermistors, such as those produced by Thermik Gerätebau GmbH, are available in the form of small “cylinders” and, put simply, consist of a protective sheath, electrodes and a semiconducting ceramic inside. The sheathing serves to protect the thermistors from environmental influences such as moisture and chemical substances as well as from mechanical stress.

The electrodes of the thermistors enable the electrical connection in a circuit, while the “inner workings” perform the actual function of the thermistors. In PTC thermistors, ceramic mixtures of semiconducting materials are sintered into shape and doped with so-called dopants. The combination serves to modify the electrical properties on the one hand and to create the PTC effect on the other.

To explain the PTC effect, it is necessary to switch to the microscopic level. If you place the ceramic material of a thermistors under a microscope, you will see a composition of countless small grains. Barriers to the flow of electrons are created at the interfaces of these grains. At low temperatures, electrons can overcome the barriers easily and unhindered – the resistance is low. If the temperature rises, the barriers “increase”, the flow of electrons becomes more difficult and thus the resistance increases.

PTC thermistors can be customised to specific applications by changing the composition of the ceramic material, size and shape. The complex interaction of material, physical structures and electrochemical configurations makes PTC thermistors suitable as highly precise and reliable sensors for monitoring temperatures.

What are PTC thermistors from Thermik used for?

The high-quality PTC thermistors from Thermik Gerätebau GmbH fulfil two main tasks in electronic devices. Firstly, the thermistors serve as protective elements and secondly, they can be used to control temperatures.

In their function as a protective element, PTC thermistors reliably prevent overheating. If devices that generate heat – such as irons, heaters or electric motors – reach a predefined critical temperature zone, the thermistors reduce the current flow by increasing resistance, thereby limiting heat generation. For the end user, this means increased safety – the risk of fire is minimised.

In industrial environments, PTC thermistors are also used to control and compensate temperatures. As the resistance changes predictably with the temperature, the components are ideally suited for use in temperature control loops. Common fields of application for thermistors from Thermik GmbH are devices in which a constant temperature must be maintained – for example in medical devices or food industry systems. Here, thermistors are installed as part of complex feedback systems in order to continuously monitor and independently control temperatures.

Incidentally, high-quality PTC thermistors also contribute to the energy efficiency of appliances. By limiting the current flow, unnecessary energy consumption is avoided “by the way” and the service life of the appliances is extended at the same time.

What makes Thermik thermistors so special?

The PTC thermistors from Thermik Gerätebau GmbH are recognised worldwide as being particularly reliable, durable and of high quality.

The components can be used via tripping devices to switch off load circuits or for the electronic evaluation of a wide range of technical applications. Depending on the design, response times of five to a maximum of ten seconds can be achieved – a value that is significantly lower than that of competitor products.

As with all Thermik products, sustainable functionality and reliable performance over the entire life cycle play a key role for PTC thermistors. The technical properties are enhanced by a significantly higher proportion of precious metals in the thermal products.

In addition, there are fully automated testing procedures for each individual order, which ensure the quality of the thermistors and rule out system errors. Thanks to specialised suppliers with unique selling points, Thermik has access to unique reference parts that are simply not available to competitors. In other words, in direct comparison with the products of market competitors, thermistors are always smaller, higher quality and more powerful.

Thermik’s special level of quality is reflected in a truly unique feature: every single one of the rare complaints worldwide lands directly on the Managing Director’s desk! On the one hand, this shows how few complaints there are from the market and, on the other, it demonstrates the high value placed on service and quality within the Thermik group of companies.

The future is green

In the course of the energy transition, numerous technologies have been and continue to be required to make PTC thermistors from Thermik safer and more energy-efficient. Fans, pumps, generators, electric motors, electric heaters, circuit boards and semiconductors or entire electric drive trains: for Thermik Gerätebau GmbH, the “green times” are truly dawning. The company has been positioned in all relevant areas of Green Tec from the very beginning and, as a “hidden champion”, supports the path to a more ecological future with high-quality components.