1. A programmable apparatus for determining the running speed of an ac induction motor, the apparatus comprising: a vibration transducer for sensing vibration generated by the motor and producing vibration signals corresponding to the sensed vibration; a flux sensor for sensing flux generated by the motor and producing flux signals corresponding to the sensed flux; signal conditioning circuitry for processing the vibration and flux signals to produce processed vibration and flux signals; and a signal processor operable to receive the processed vibration and flux signals and to determine the running speed of the motor by: performing a first analysis on at least one of the processed vibration and flux signals according to a first predetermined criterion to determine one or more candidate speeds and whether speed will be determined based on the first analysis or whether a second analysis is required; and selectively performing a second analysis if required by the first analysis, said second analysis including the steps of comparing the processed vibration signals to the processed flux signals and determining running speed based on said comparison.