Patent ID: 8129873

Claim:
A coolant flow reduction monitoring system for a rotary electric machine having stator coils within a plurality of slots of a stator thereof, the stator coils cooled by a coolant flowing in a plurality of passages provided in the stator coils, the system comprising: an outlet temperature sensor for measuring a coolant outlet temperature of the coolant in an outlet of at least one of the plurality of passages and outputting a signal indicative of each; a slot temperature sensor for measuring a temperature in at least one slot at a location along a length of the at least one slot and outside of the stator coils therein, and outputting a signal indicative thereof; an inlet temperature sensor for measuring a coolant inlet temperature of the coolant at an inlet to the plurality of passages and outputting a signal indicative thereof; and a coolant flow reduction monitor for generating an alarm indicating a coolant flow reduction based on the at least one coolant outlet temperature, the at least one slot temperature and the coolant inlet temperature, wherein the coolant flow reduction monitor generates the alarm in response to a rate of change of an average of a difference between the at least one coolant outlet temperature and the coolant inlet temperature exceeding a first threshold, and a rate of change of an average of a difference between the at least one slot temperature and the coolant inlet temperature exceeding a second threshold.