Abstract: An aspect of the invention is directed to a variable sensor head for use in multiple electric machines with varying slot openings comprising a ferromagnetic core; a first adjustable portion and a second adjustable portion positioned in communication with the ferromagnetic core wherein the first adjustable portion and the second adjustable portion are adjusted to fit between a plurality of slot openings of varying widths between a pair of lamination teeth of an electric machine. According to another embodiment, the first and second adjustable portions are sliding portions where the sliding portions may be spring biased to provide a close fit between the pair of lamination teeth. According to another embodiment, the first and second adjustable portions are adjustable screws.

Abstract: An online insulation condition monitoring system for a rotating electric machine, includes a differential current sensor and a voltage sensor coupled to the machine, for measuring values for the instantaneous differential current and the instantaneous phase voltage respectively. A processing module is configured for converting the values for the instantaneous differential current and the instantaneous phase voltage to respective values for phasor current and phasor voltage. The processing module further calculates an angular relationship between phasor current and phasor voltage and generates an output based on the calculated angular relationship, as an indication of insulation condition.