Changes

Every technical device has to fulfill a series of requirements. Some of those which are important for agreement between contact manufacturer and user are part of DIN 40042 standard and described here in a summarized version:

Availability (for use) defines the probability of a system or switching device to be in a functional stage at a given time

Both, availability and reliability, are guaranteed for a pre-determined time span and/or a specific number of switching operations. This means they warrant the life expectancy of a switching device. At the end of the live span the failure rate exceeds pre-defined limit values.

Electrical life is the number of operations reached under a given electrical load under specified operating conditions.

Since the criteria which determine the electrical life of switching contacts depends on the type of switching devices they are used in, they are described in more detail under the testing procedures in information and power engineering.

==<!--13.2-->Testing of Contact Surface Layers==