The problem to be solved is to provide a system and a method to protect the regulator rectifiers from the reverse voltage condition and the short circuit condition, and the problem is solved in the present invention by a system and a method that use a protection device including a control unit that receives an input from the circuit based on the reverse voltage condition and the short circuit condition, and based on the existence of at least one of the condition or a combination thereof, the control unit switches a switching unit from an ON state to an OFF state, thereby breaking the circuit between the regulator rectifier device and the load section, thus protecting the regulator rectifier device.

An electrical AC/DC converter arrangement includes: an AC circuit breaker; a rectifier; at least one smoothing capacitor; at least one first isolating relay for electrical isolation; at least one first current sensor; and a control and monitoring unit. An input of the AC circuit breaker forms an AC input of the arrangement. An output of the AC circuit breaker is connected, at least indirectly by a circuit, to an input of the rectifier. The at least one smoothing capacitor connects a first output of the rectifier to a second output of the rectifier. The first output of the rectifier is connected, at least indirectly by a circuit, to an input of the at least one first isolating relay. An output of the at least one first isolating relay forms a first DC output of the arrangement and connects a DC network to at least one first DC load.

A power conversion system includes a first switch configured to be connected between a first phase of a polyphase alternating current (AC) power source and an electrical load and a first diode configured to be connected between the first phase of the polyphase AC power source and the electrical load, the diode configured to conduct a current from the AC power source to the electrical load. The power conversion system also includes a control unit configured to interface with the first switch to close, responsive to the occurrence of a short circuit fault, the first switch during a negative current portion of the AC cycle of the first phase of the polyphase AC power source and open, responsive to the occurrence of the short circuit fault, the first switch during a positive current portion of the AC cycle of the first phase of the polyphase AC power source.

Even when one power conversion device among a plurality of power conversion devices connected in parallel experiences a short circuit, the other power conversion devices having experienced no short circuit can be promptly restarted. Each power conversion device includes: a short circuit occurrence determination unit configured to determine, on the basis of a current value at an output terminal, whether or not a short circuit has occurred; a short circuit elimination determination unit configured to determine, on the basis of a current value and a voltage value at the output terminal, whether or not the short circuit has been eliminated; and a current interruption unit configured to, on the basis of determination by the short circuit occurrence determination unit and determination by the short circuit elimination determination unit, interrupt current that flows from a power conversion unit to the output terminal or cancel the interruption.

An improved electric circuit structure for short circuit protection is applicable to examining a device under test, comprising a circuit breaking element, a thermistor, a filtering and rectifying module and a capacitor. A first end of the circuit breaking element is connected to a power source. The filtering and rectifying module is connected to a second end of the circuit breaking element, a ground, a first end of the thermistor and a first end of the capacitor. A second end of the capacitor is connected to a second end of the thermistor. The capacitor is connected in parallel with the device under test. The circuit breaking element disclosed in the present invention is a ceramic tube fuse and forms an open circuit when the device under test forms a short circuit. Meanwhile, the ceramic tube fuse withstands voltage between its first and second end without generating any physical damage.

An electric grid includes feed-ins, loads, and a distribution grid, which is arranged therebetween. The distribution grid comprises at least one busbar and at least one device for opening or closing a DC circuit. The at least one device includes an electric switch for opening or closing the DC circuit, a fault current detector, a trigger unit, a precharging device, and a control unit for automatically closing the electric switch after the precharging process. The electric switch opens the DC circuit via the trigger unit if a fault current is detected by the fault current detector, and the precharging device restores the voltage on the busbar prior to closing the electric switch.

A hybrid circuit breaker includes a semiconductor circuit breaker, connected between a first output end of a converter of a power supply or a source branch and a first end of a damping module; a first mechanical circuit breaker, connected in parallel to the semiconductor circuit breaker, an energy absorber, connected in parallel to the semiconductor circuit breaker, and a controller coupled to the semiconductor circuit breaker and the first mechanical circuit breaker, and when a current flowing through the converter is greater than a safe current, the controller is configured to control the first mechanical circuit breaker to be disconnected, and control the semiconductor circuit breaker to be closed.

A switching device for opening a current path of a direct-voltage network, which current path has source-side and load-side inductors, the switching device includes at least two switching modules, which are connected in series, each of the switching modules having at least one controllable semiconductor switching element, in parallel with which a series circuit of a resistor and a capacitor is connected. During operation of the switching device in order to open the current path, the controllable semiconductor switching element of at least one of the switching modules is switched into a conductive state with a duty cycle until the energy stored in the inductors has been dissipated, the duty cycle being dependent on the difference between the actual voltage and a target voltage across the semiconductor switching element, the target voltage being calculated at least from the system voltage of the direct-voltage network and the number of switching modules.

A device is for opening or closing a DC circuit with at least one busbar. The device includes an electric switch for opening or closing the DC circuit; a fault current detector; a trigger unit and a precharging device. The electric switch opens the DC circuit via the trigger unit upon a fault current being detected by the fault current detector. Further, the precharging device restores the voltage on the busbar prior to closing the electric switch. The device further includes a control unit for automatically closing the electric switch after the pre-charging process.

An electrical AC/DC converter arrangement includes: an AC circuit breaker; a rectifier; at least one smoothing capacitor; at least one first isolating relay for electrical isolation; at least one first current sensor; and a control and monitoring unit. An input of the AC circuit breaker forms an AC input of the arrangement. An output of the AC circuit breaker is connected, at least indirectly by a circuit, to an input of the rectifier. The at least one smoothing capacitor connects a first output of the rectifier to a second output of the rectifier. The first output of the rectifier is connected, at least indirectly by a circuit, to an input of the at least one first isolating relay. An output of the at least one first isolating relay forms a first DC output of the arrangement and connects a DC network to at least one first DC load.