An inverter system includes a converter, an inverter, a first switch SW1 that connects between the converter and an AC power source, a capacitor that smooths a DC power in a DC bus, a resistor Rr connected from a positive voltage side of the DC bus to ground, a second switch SW2 that connects between the resistor Rr and ground, and a controller that controls drive of the inverter system. The controller is configured to: after charging the capacitor, while the first switch SW1 is in an OFF state, turn on the second switch SW2 and obtain a first across voltage E.sub.R1 of the resistor Rx; turn on an element, among semiconductor elements of the inverter, that is connected to the negative voltage side of the DC bus, and then obtain a second across voltage E.sub.R2 of the resistor Rx; and inspect insulation resistance of a motor based on the across voltages E.sub.R1, E.sub.R2.

An inverter system includes a converter, an inverter, a first switch SW1 that connects between the converter and an AC power source, a capacitor that smooths a DC power in a DC bus, a resistor Rr connected from a positive voltage side of the DC bus to ground, a second switch SW2 that connects between the resistor Rr and ground, and a controller that controls drive of the inverter system. The controller is configured to: after charging the capacitor, while the first switch SW1 is in an OFF state, turn on the second switch SW2 and obtain a first across voltage E.sub.R1 of the resistor Rx; turn on an element, among semiconductor elements of the inverter, that is connected to the negative voltage side of the DC bus, and then obtain a second across voltage E.sub.R2 of the resistor Rx; and inspect insulation resistance of a motor based on the across voltages E.sub.R1, E.sub.R2.

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 system for magnetic field testing comprising a magnetic field generation device configured to generate a magnetic field in a rotor, a plurality of magnetic field measurement devices configured to measure a magnetic field at a predetermined position on the rotor, a drive mechanism configured to rotate the rotor and a test system configured to record the plurality of magnetic field measurements as a function of an angular position of the rotor.

A system for magnetic field testing comprising a magnetic field generation device configured to generate a magnetic field in a rotor, a plurality of magnetic field measurement devices configured to measure a magnetic field at a predetermined position on the rotor, a drive mechanism configured to rotate the rotor and a test system configured to record the plurality of magnetic field measurements as a function of an angular position of the rotor.

The invention concerns a method for coupling to the grid a hydraulic unit having a synchronous generator, a runner, and wicket gates. The method includes a step of increasing the flow of water into the runner from a time t.sub.0 to a time t.sub.1 so that the rotation frequency of the rotor of the synchronous generator is, at time t.sub.1 equal to the frequency of the grid, and closing the circuit breaker at time t.sub.1. A sub-interval from a time t2 to time t1 is defined, with t0<=t2<t3<=t1, wherein a sub-step is executed to apply an adjustment torque to the shaft line via a first actuator that controls the flow of water into the runner and a second actuator coupled to a stator of the synchronous generator.

According to one embodiment, an insulation diagnostic system comprising: a peak-value acquisition circuit configured to acquire at least one peak value of a section corresponding to local discharge of a voltage signal acquired by at least one sensor that detects the voltage signal in a non-contact manner; a function acquisition circuit configured to acquire a calculation function for calculating charge amount related to the discharge based on at least two peak values acquired from the voltage signal that is detected by the sensor by applying a test voltage to a rotating electrical machine while the rotating electrical machine is stopped; and a charge-amount calculation circuit configured to calculate the charge amount related to partial discharge of the rotating electrical machine based on the calculation function and the peak value obtained from the voltage signal that is detected by the sensor during operation of the rotating electrical machine.

A system to reconfigure a motor from induction mode to synchronous mode at a zero crossing of the field voltage during startup using only stator current signals is described herein. The zero crossing may be detected by asymmetry induced in the stator currents by a current asymmetry inducing module of the motor. The current asymmetry inducing module may include a resistor and diode in series and in parallel with a discharge resistor of the field windings. Asymmetry is induced in the current obtained from the stator, and used to determine a zero crossing of the field voltage. Upon the rotor reaching a startup frequency and the detected zero-crossing of the field voltage, the motor may be reconfigured from induction mode to synchronous mode.

This disclosure presents a portable load bank apparatus, system, method of control, and method of manufacture. A portable load bank apparatus may comprise one or more of a vehicle, a load bank, a set of batteries, a set of battery chargers, one or more processors, and/or other components. The load bank may be configured to perform a load test of an external power source. The processor(s) may be configured to cause one or more battery chargers in the set of battery chargers to direct an amount of a power output received by the load bank from the external power source to the set of batteries. The set of batteries may be used to provide electrical energy to one or more of an electric motor of the vehicle, one or more other electric vehicle, and/or other sources that may need electrical energy.

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.