Patent ID: 7296978

Claim:
A method of operating an air compressor system for a railroad locomotive comprising an air compressor, an electric motor receiving electric power from an alternator mechanically coupled to a locomotive engine and driving the air compressor, with the motor being directed to operate at a commanded speed and operating at an actual speed when driving the air compressor, the method comprising: determining the commanded speed of the electric motor; determining the actual speed of the motor in driving the air compressor; determining a parameter indicative of the slip between commanded and actual speeds, wherein the value of the slip is based at least in part on the following relationship: a difference between locomotive engine speed and compressor speed adjusted by a ratio of a number of active poles relative to a total number of poles of the motor predicting a faulted condition in the operation of the air compressor system in response to the parameter; and generating an indication of the faulted condition regarding the operation of the air compressor system.