The temperature class of a transformer is composed of the ambient temperature and the respective insulation class. For example, the temperature class for a standard transformer can be defined as follows: 40°C (ta 40°C/B)
The ambient temperature is described in DIN EN 60204-1. It describes the temperature in electronics which guarantees optimum operation of electronic components or systems. If the ambient temperature is not maintained, components and systems can have low efficiency and the product life can be reduced. In addition, failure to maintain the ambient temperature for electronic equipment can result in the risk of destruction, i.e. complete failure of the respective component or machine. A standard transformer runs in an ambient temperature of 40°C. Exceptions are possible.
Insulating material classes are defined in DIN EN 60085. An insulating material class defines insulating materials (such as enameled copper wire) in terms of their maximum operating temperature. The classes refer to both electrical insulation materials (EIM) and electrical insulation systems (EIS). In electrical engineering, electronic components can reach very high temperatures, which can impair or destroy insulation. The insulating material classes are therefore intended to prevent thermal decomposition from destroying the insulating materials during use or rendering them non-functional. The insulating materials are divided into heat classes with different limit temperatures with regard to their heat resistance. These temperatures must not be exceeded permanently during operation in order to guarantee a longer service life.