A surge protection system is provided. The surge protection system includes an input capacitor, a surge protection circuit, and a controller. When the input voltage starts to be transmitted to the input capacitor, a surge current is generated. The surge protection circuit includes a first path and a second path. The surge protection circuit is coupled to a second end of the input capacitor via the first path, so that the surge current is transmitted via the first path. The controller is coupled to the surge protection circuit. The controller is configured to provide a control signal to the surge protection circuit to switch the first path to the second path to be coupled to the second end of the input capacitor.

In aspects, the present invention provides a method for controlled energizing of a transformer (150) being connected to a first electrical subsystem (110) through a first circuit breaker (140). The method comprises acquiring electrical current waveform in a first phase of the transformer during a closing operation of the first circuit breaker at an instance for switching determined by a controller (130), determining a first peak (310) in the current in the first phase within a first predetermined time window (Tpw), calculating a first correction factor for adjusting the instance for switching in the first phase, and adjusting the instance for switching based on the calculated first correction factor for performing a next controlled energization at the adjusted instance of switching in the first phase.

A system for controlling power provided to an electronic device includes a driver configured to drive the electronic device and having an on state and an off state. The system further includes a sensor configured to detect detected electrical data corresponding to electricity provided to the driver. The system further includes a controller configured to compare the detected electrical data to a threshold electrical value and to determine a fault condition in response to the detected electrical data being greater than or equal to the threshold electrical value and to turn the driver to the off state in response to the controller determining the fault condition.

An electronic circuit includes a switch coupled between an input terminal intended to receive a first voltage and an output terminal coupled to a decoupling capacitor and intended to also be coupled to a load. A comparison stage is configured to compare the first voltage and a second voltage that is present at the output terminal. A first adjustment stage is configured to limit a positive inrush current flowing between the input terminal and the output terminal and a second adjustment stage is configured to limit a negative inrush current flowing between the output terminal and the input terminal. A control circuit is configured to activate either the first adjustment stage or the second adjustment stage as a function of a result of the comparison.

An intelligent electronic device (IED) may obtain a voltage measurement matrix based on an arrangement of a transformer in a power system. The TED may obtain a delta connection compensating angle based on the location of the circuit breaker and the transformer arrangement. The IED may obtain voltage measurements of the transformer. The TED may determine a residual flux value of the transformer based at least in part on the voltage measurements, the voltage measurement matrix and the delta connection compensating angle. The TED may send a signal to a circuit breaker of the transformer to connect the transformer to the power system based at least in part on the system voltage and residual flux value.

A source circuit, a power supply and an electric system. The source circuit includes at least one voltage source supplied from a mains circuit and used to provide at least one voltage for at least one device and at least one switch respectively connected to the at least one voltage source and controlled to be turned on according to a voltage of the mains circuit and/or at a timing after the mains circuit being applied corresponding to the device.

An electric working machine according to one aspect of the present disclosure comprises a motor, a rectifier circuit, a capacitor, a series switching element, a resistive element, a drive circuit, a peak voltage value acquirer, and a controller. The capacitor smooths power rectified by the rectifier circuit. The series switching element is coupled in series with the capacitor. The resistive element is coupled in parallel with the series switching element. The controller brings the series switching element into conduction in a case where AC power is inputted to the rectifier circuit and where a specified conducting condition based on a peak voltage value acquired by the peak voltage value acquirer is satisfied.

A drive device for an electric motor according to the present invention includes a first relay that turns a power supply line on and off leading from a power supply to an electric motor, a resistor provided on a bypass line that bypasses the first relay, a second relay that turns the bypass line on and off, a relay control circuit that outputs a relay control signal common to the first relay and the second relay, and a delay unit that delays the turn-on timing based on the relay control signal of the first relay later than the turn-on timing based on the relay control signal of the second relay. This configuration makes it possible to add a function for suppressing an inrush current without increasing the number of output connectors of a relay control circuit.

A power supply includes a power converter, a protection circuit, and a control circuit. The protection circuit includes an input for receiving an input voltage, an output for providing an output voltage to the power converter, a first switching device coupled in a current path between the input and the output, and a second switching device coupled across the first switching device. The control circuit is configured to sense the input voltage and the output voltage, in response to the output voltage exceeding a first defined threshold, turn off the first switching device and turn on the second switching device to supply power to the power converter, and in response to the input voltage exceeding a second defined threshold, turn off the second switching device to disconnect the power source from the power converter. Other example power supplies and protection circuits are also disclosed.

The present invention provides a phase control device applied to a three-phase circuit including a three-phase transformer and a three-phase breaker that turns on/off the transformer. The device suppresses an excitation rush current generated in the transformer. The device includes a controller that closes any one phase of the breaker as a closing first phase and subsequently closes the other phases, a determiner that determines the closing first phase based on residual magnetic fluxes of the respective phases in the transformer, a determiner that determines, based on a pre-arc characteristic and a closing time variation characteristic of the breaker, target closing phases and target closing times of the closing first phase and the other phases, a calculator that calculates a closing time of each phase of the breaker, and an operation time table that stores, as a median of the variation characteristic represented by a normal distribution, the calculated time.