This part of IEC 60947 specifies rules for control units, which perform the switching functions
in response to the thermal detectors incorporated in rotating electrical machines according to
IEC 60034-11, and the industrial application.
It specifies rules for that type of system comprising a positive temperature coefficient (PTC)
thermistor detector having particular characteristics, and its associated control unit.
The PT100 detectors are covered by IEC 60751, where the resistor values are given
according to the temperatures of the detector.
The present rules lay down the characteristics of association of this particular positive
temperature coefficient thermistor detector and its associated control unit (designated “Mark A
detector” and “Mark A control unit”), when they are used in thermal protection systems.