EN 60947-8 specifies the rules for control units that perform switching functions in response to thermal detectors in rotating electrical machines, according to EN 60034-11. This standard covers systems with positive temperature coefficient (PTC) thermistor detectors and their associated control units, known as Mark A detectors and Mark A control units, used in thermal protection systems. PT100 detectors are covered separately by EN 60751, where resistor values correspond to detector temperatures. The standard outlines the characteristics of the thermistor detector and control unit association, noting that some operational characteristics depend on the thermal detectors and machine characteristics. Responsibilities for specifying values, ensuring compliance, and conducting tests are also defined.