The Thermik system

Bimetallic switches have proven their worth in terms of temperature control. However, there are differences in bimetal temperature limiters that affect quality and performance. Thermik has therefore developed their own system, which works reliably thanks to continuous bimetallic discs and offers many advantages over conventional bimetallic switches. 

In order to understand the uniqueness and superior functioning of Thermik's temperature controllers, it is necessary to consider the other systems. How are thermal bimetals used in these systems?


Temperature controllers with conventional systems


Compared to Thermik temperature limiters, in conventional systems simple bimetal temperature limiters are manufactured as a tongue switch with a welded contact. The contact pressure between the two changes consistently in line with the temperature which results from the bimetal's ability to move. Thus, contact resistance is temperature-dependent in a closed state. There is a possibility that the pressing force decreases before the shutdown temperature is reached and therefore forms an arc due to the high contact resistance. As a result, the temperature limiter can heat up to an extent that it switches off prematurely. Under certain circumstances, the contacts can weld together, which results in the opening of the temperature limiter being prevented and permanently suspends the protection function in an unnoticeable way. This guarantees less reliable protection in the event of overheating or a system failure.

Properties of conventional bimetallic switches:

  • Increased vibration sensitivity of the tongue switch near the nominal switching temperatures
  • increased self-heating in the range of the switching temperature (therefore relatively undefined falling switching temperature)
  • in unfavorable cases contact wear and tear, contact erosion due to arcing and premature switching

To minimise these and other negative implications, Thermik continues to improve existing systems to provide customers with innovative solutions which would not be otherwise available on the temperature monitor market. As a development supplier and innovation partner, Thermik is therefore not only the world market leader, but also has the widest range of customer-oriented solutions with regards to application of temperature limiters in construction components.

Temperature limiter in line with the Thermik system


In order to improve the function and the switching behaviour of the bimetal temperature limiter, another spring washer was inserted - in contrast to conventional systems - so that the bimetallic disc can operate consistently. This type of control unit can have a higher current carrying capacity as well as much lower levers of contact erosion and a longer service life.

The functional parameters of bimetal discs change depending on load and period of use - this aging process is not completely avoidable in any temperature limiter. Since the thermal load of the bimetallic switch cannot be lowered due to the application, the only option is to improve the parameter stability by reducing the mechanical stress. Consistently operating discs are exposed to less mechanical stress than non-continuously operating metal domes.

Edge in quality because of Thermik

Some of the main advantages of systems with continuously operating bimetal discs are higher contact stability and greater contact pressure, cost-effective production and the exact switching point reaction, for which only the ambient temperature is decisive. The demands on quality and performance are very high at Thermik. Through continuous research and development, the temperature limiters have been optimised in such a way that they have a longer service life due to the low levels of mechanical stress on the bimetal discs. Additionally, the thermal temperature limiters are characterised by a higher operating capacity, better long-term stability and precise switching point accuracy. This is the result of decades of experience, sound know-how and the pursuit of innovation. For this reason, all Thermik products are state of the art (in terms of design, material selection and composition) - with a large number of national and international intellectual property rights.


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