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: Insulation condition monitoring systems and methods for a rotating DC electric machine, the method comprising: measuring a first set of values for an instantaneous differential current and an instantaneous voltage during operation of the rotating DC electric machine; calculating a value for a phasor current and phasor voltage based upon the first set of values of the instantaneous differential current and the instantaneous voltage, respectively; calculating an angular relationship between the phasor current and the phasor voltage; and determining insulation condition based on the angular relationship.

Abstract: A probe for use in detecting abnormalities in an electrical device having a wedge depression of no more than 100 mils. The probe includes a solid core surrounded by a sense coil. The ends of the core are arranged in a contact-free, spaced relationship between and at least partially above opposed surfaces of adjacent lamination teeth of a stator. Air gaps are maintained between the ends of the probe core and the opposed surfaces. The total of the two air gaps is constant. The probe is supported on a carriage arrangement and moved along the teeth. Variations in leakage flux produced with the stator energized with an energization winding to produce a flux which is a few percent of a normal energization level, are monitored.

Abstract: A differential probe is scanned along a stator core tooth portion to detect lamination faults. The probe utilizes two magnetic flux injection yokes arranged side-by-side in relatively close proximity, each yoke having two arm portions and two core-tooth flux-injection surfaces, each yoke being wound with an excitation coil winding and at least one yoke-arm of each yoke having a magnetic flux sensor. Current is supplied to the excitation coil windings on each yoke to inject magnetic flux into the stator core laminations while the probe is moved in a scanning process along the core teeth across the laminations. The magnetic flux differential detected at adjacent regions in the core by flux sensors on each of the two yokes is used to incrementally evaluate the core for laminations faults. The output produced by the differential probe may be converted to a digital signal and provided to a computer system for storage and future analysis.

Abstract: A probe includes at least one core and at least one sense coil associated with the core. The ends of the core are arranged in a contact-free, spaced relationship between opposed surfaces of adjacent lamination teeth of a stator. Air gaps are maintained between the ends of the probe core and the opposed surfaces. The total of the two air gaps is constant. The probe is supported on a carriage arrangement and moved along the teeth. Variations in leakage flux produced with the stator energized with an energization winding to produce a flux which is a few percent of is normal energization level, are monitored.

Abstract: A differential probe is scanned along a stator core tooth portion to detect lamination faults. The probe utilizes two magnetic flux injection yokes arranged side-by-side in relatively close proximity, each yoke having two arm portions and two core-tooth flux-injection surfaces, each yoke being wound with an excitation coil winding and at least one yoke-arm of each yoke having a magnetic flux sensor. Current is supplied to the excitation coil windings on each yoke to inject magnetic flux into the stator core laminations while the probe is moved in a scanning process along the core teeth across the laminations. The magnetic flux differential detected at adjacent regions in the core by flux sensors on each of the two yokes is used to incrementally evaluate the core for laminations faults. The output produced by the differential probe may be converted to a digital signal and provided to a computer system for storage and future analysis.

Abstract: A probe for use in detecting abnormalities in an electrical device having a wedge depression of no more than 100 mils. The probe includes a solid core surrounded by a sense coil. The ends of the core are arranged in a contact-free, spaced relationship between and at least partially above opposed surfaces of adjacent lamination teeth of a stator. Air gaps are maintained between the ends of the probe core and the opposed surfaces. The total of the two air gaps is constant. The probe is supported on a carriage arrangement and moved along the teeth. Variations in leakage flux produced with the stator energized with an energization winding to produce a flux which is a few percent of a normal energization level, are monitored.

Abstract: A probe includes at least one core and at least one sense coil associated with the core. The ends of the core are arranged in a contact-free, spaced relationship between opposed surfaces of adjacent lamination teeth of a stator. Air gaps are maintained between the ends of the probe core and the opposed surfaces. The total of the two air gaps is constant. The probe is supported on a carriage arrangement and moved along the teeth. Variations in leakage flux produced with the stator energized with an energization winding to produce a flux which is a few percent of is normal energization level, are monitored.

Abstract: A method for evaluating core stack pressure includes: positioning a magnetic yoke near the core, the magnetic yoke being wound by an excitation winding; supplying current to the excitation winding to inject magnetic flux into the core; measuring a signal resulting from the injected magnetic flux; and using the measured signal to evaluate the core stack pressure. A system for implementing the method includes the magnetic yoke; a current supply for supplying the current; a sensor for measuring the signal; and a computer for using the measured signal to evaluate core stack pressure.

Abstract: A device and method to estimate the resistance of a stator winding of an AC induction motor is provided. The device includes an AC induction circuit connecting one phase of the AC induction motor to an AC source. The circuit includes a resistor and a switch connected in parallel. The switch is alternatively closed during the half cycles of the AC current supplied to the motor so as to inject a DC voltage and current bias to the AC motor. The resistance of the stator winding is estimated in response to the DC voltage and current bias.

Abstract: A device and method to estimate the resistance of a stator winding of an AC induction motor is provided. The device includes an AC induction circuit connecting one phase of the AC induction motor to an AC source. The circuit includes a resistor and a switch connected in parallel. The switch is alternatively closed during the half cycles of the AC current supplied to the motor so as to inject a DC voltage and current bias to the AC motor. The resistance of the stator winding is estimated in response to the DC voltage and current bias.