With a method and a device for detecting a partial discharge at a winding of an electrical machine, electromagnetic first measuring signals are detected in a partial discharge frequency range and electromagnetic second measuring signals are detected in an interference frequency range. A time window around a first measuring signal is predefined, and an identification criterion is defined for a partial discharge signal and an interference signal criterion is defined for a second measuring signal. A determination is made as to a partial discharge when a first measuring signal is detected that meets the identification criterion and when, in the time window around the first measuring signal, no second measuring signal that meets the interference signal criterion is detected. A quality of the detected partial discharge is assessed based on a characteristic value of the second measuring signal.

A monitoring system includes an array of optical sensors disposed within a transformer tank. Each optical sensor is configured to have an optical output that changes in response to a temperature within the transformer tank. An analyzer is coupled to the array of optical sensors. The analyzer is configured to determine a sensed temperature distribution based on the sensed temperature. The sensed temperature distribution is compared to an expected distribution. Exterior contamination of the transformer tank is detected based on the comparison.

A system includes a monitoring and/or protection system that includes an insulation derivation circuit. The insulation derivation circuit is configured to derive a first temperature compensation curve based on a first temperature and a first current, and the monitoring and/or protection system is configured to communicatively couple to a first current sensor configured to sense the first current traversing a first phase of a stator winding of a motor, a generator, or a combination thereof. The insulation derivation circuit is also configured to communicatively couple to a first temperature sensor configured to sense the first temperature of the stator when the stator is energized, and the temperature compensation curve is configured to map a temperature to a leakage dissipation factor.

A hairpin type stator inspection apparatus is provided for testing performance of a stator wound with hairpin type stator coils. The hairpin type stator inspection apparatus includes: a conveyor provided on a frame for transferring the stator including a plurality of stator terminals along a predetermined path: a plurality of clamp terminals, which are installed to be movable to the frame by a driver in up and down, front and rear, and left and right directions in order to clamp the stator terminals: a controller that applies a driving control signal to the driver to change a position of the clamp terminals according to a position of the stator terminals; and an inspection portion that applies power to the stator terminals through the clamp terminals and inspects the electrical circuit of the stator.

A method for estimating at least one leakage inductance of a 3n-phase electrical machine includes performing a first machine investigation scheme and a second machine investigation scheme, the first scheme including ordering a machine drive stage to control one of the 3-phase windings, obtaining a first set of measured currents from the 3-phase winding and processing the first set of measured currents to obtain primary characteristics of an electrical quantity of the electrical machine, the second scheme including ordering the machine drive stage to control all the 3-phase windings using a VSD control model, the controlling involving only controlling a first fundamental subspace of the VSD control model, obtaining a second set of measured currents from all 3-phase windings and processing the second set of measured currents to obtain a leakage inductance estimate and secondary characteristics of the electrical quantity, for which leakage inductance estimate the primary and secondary characteristics match.

A measuring apparatus for measuring losses in a circumferential segment for an electrical machine is provided. The measuring apparatus includes a frame to which a circumferential segment is fixable and a flux element attached to the frame so that a circumferential segment fixed to the frame and the flux element are radially distanced and that a magnetic flux generated by a current flowing along the coil windings housed in one slot of the circumferential segment follows a magnetic flux path including at least a first path portion in one tooth circumferentially adjacent to the one slot, a second path portion in the yoke, a third path portion in the other tooth circumferentially adjacent to the one slot and a fourth path portion in the flux element.

Provided are a short circuit state analyzer to compare difference value when the AC excitation current is applied at a first frequency with a threshold value, to estimate a short circuit resistance from the difference value based on data indicating a relationship between the short circuit resistance and the difference value at the first frequency when the difference value is smaller than the threshold value, to cause an excitation power supply to apply the AC excitation current to the field windings at a second frequency lower than the first frequency when the difference value is equal to or greater than the threshold value, and to estimate the short circuit resistance from a difference value obtained by the AC excitation current at the second frequency based on data indicating a relationship between the short circuit resistance and the difference value at the second frequency.

A large current flowing when energization by normal load drive control is performed at the time of a load short-circuit is prevented. A load drive device 100 includes drive switches 61 and 62 that turn on or off the current supplied from a power source to a load 70, a switch drive circuit 20 that transmits a drive signal to the drive switches 61 and 62 based on a control command from an arithmetic device 10, and a constant current source 40 that supplies the current to the load 70 without passing through the drive switches 61 and 62. Then, the switch drive circuit 20 performs control so as not to turn on either the drive switches 61 or 62 when the voltage between both ends of the load 70 becomes equal to or less than the determination value in a state where the drive switches 61 and 62 are turned off and in a state where the current is supplied from the constant current source 40 to the load 70.

Provided is an inspection device for a rotating electric machine, the inspection device including a photographing device, a drive mechanism, a display, and a controller. The photographing device photographs a pattern formed on a surface of a wedge constituting part of an armature. The drive mechanism moves the photographing device with respect to a stator functioning as the armature. The controller detects strain of the wedge by comparing image data of the pattern photographed by the photographing device with reference data of the pattern. In this manner, the inspection device for a rotating electric machine can easily detect the strain of the wedge. Further, the controller estimates loosening of the wedge based on the strain of the wedge, and informs an operator of the rotating electric machine through the display that the loosening of the wedge has occurred.

A testing device for testing a medium voltage starter or breaker and method of use. The testing device is configured to test starter motors in the 2,300 volts to 13,800 volts range while protecting the technician from high voltages. The testing device is electrically connectable to a variety of different medium voltage starter motors via an umbilical connector harness adapted for each specific starter. A tester control board is organized to indicate the functionality of the medium voltage starter electrical components. The control board is used to isolate circuits in open and closed positions and visual indicators are used to verify proper operation of the starter coil, primary contacts, and auxiliary contacts.