The vacuum encapsulation guarantees excellent dielectric strength, safe mains isolation and high electrical safety. In addition, robustness even in difficult operation, the best possible protection in tough applications (moisture, shocks, etc.) and, as a result, a long service life. All transformers are equipped with additional safety devices, 35 VA and 55 VA types with self-resetting thermal switch (short-circuit and overload protection) from 100 VA additionally with a glass tube fine-wire fuse which can be replaced from the outside.