Eristysluokka

Eristysluokka, in English commonly referred to as insulation class, is a designation used in electrical engineering to indicate the maximum operating temperature that an insulation system can withstand without its properties deteriorating unacceptably. The classification helps engineers select suitable insulation for components such as motors, transformers, generators, cables and other electrical equipment, ensuring safety, reliability and life expectancy.

The system typically uses letter codes, for example A, B, F and H, to denote different thermal ratings. Each class corresponds to a defined maximum temperature that the insulation material can reach during normal operation or under specified overload conditions. Commonly cited values are: Class A up to about 105°C, Class B up to about 130°C, Class F up to about 155°C, and Class H up to about 180°C. These figures are indicative and can vary slightly between standards; some standards may include additional classes or slightly different limits.

In practice, the eristysluokka interacts with ambient temperature, cooling conditions and duty cycle to determine the allowable continuous operation and service life. A higher insulation class allows higher permissible temperatures and often enables tighter design margins or higher overload capability, but it may increase material costs or design complexity. The classification is specified in product data sheets and nameplates and is governed by international standards such as IEC/EN 60085 (Electrical insulation—Thermal classification) and related regional standards.

Understanding eristysluokka is essential for correct selection, safe operation, and maintenance planning of electrical equipment.