An extinguishing branch (28) for an electrical circuit (32) includes: a snubber circuit (36) including an energy storage limb (40), wherein the energy storage limb (40) includes first and second energy storage limb portions separated by a first junction (46) to define a first voltage divider, and each energy storage limb portion includes at least one energy storage device (48,50); and an arrester limb (38) connected across the energy storage limb (40), wherein the arrester limb (38) includes first and second arrester limb portions separated by a second junction (52) to define a second voltage divider, and each arrester limb portion includes at least one arrester element (54,56), wherein the first and second junctions (46,52) are connected to define a voltage divider bridge, and the voltage divider bridge is electrically coupleable to the electrical circuit (32) so as to provide, in use, a driving voltage to drive the electrical circuit (32).

A traction motor comprises a stator, a rotor core, an iron core holder, a cooling fan, a rotor, a frame, a bracket, and a bearing unit. The cooling fan includes a main plate that separates the inside and the outside of the totally-enclosed traction motor; blades provided on the bracket side of the cooling fan and along a rotational direction of the rotor; and a guide provided on the bracket side of the blades. In the bracket, inlets are provided within an area obtained when the guide is projected onto the bracket. The guide is formed such that air drawn in through the inlets is guided to a rotor shaft.

In a method for coordinating a distribution grid of different levels of electromechanical switches and automatically electrically closable apparatuses in a DC circuit, the distribution grid is arranged between feed-in devices and loads and includes at least one busbar. Each of the apparatuses includes an electrical switch to open or close the DC circuit, a fault current detection device, a tripping unit, and a pre-charging apparatus.

The direct current (DC) side fault isolator for high voltage direct current (HVDC) converters (10) includes a first set of double thyristor switches (12) connected across the line-to-line voltage terminals between first and second phases of alternating current (AC) terminals of a HVDC converter (14), and a second set of double thyristor switches (12) connected across the line-to-line voltage between the second phase and a third phase of the AC terminals of the HVDC converter (14). In use, the first and second sets of double thyristor switches (12) separate the HVDC converter (10) from an external power grid (18) during direct current (DC) side faults by turning on these thyristors (12).

A method and a device provide protection for a multi-terminal HVDC grid against faults. The method includes measuring a DC displacement voltage having a polarity and a value, determining if a short circuit fault exists by comparing the DC displacement voltage with a threshold displacement voltage and identifying a fault type based on the polarity and the value of the DC displacement voltage. The disclosed device contains a converter having a positive pole and a negative pole, a DC-switch substation, a DC line connecting the converter and the DC-switch substation and a transient fault detector. The transient fault detector contains a positive voltage sensor sensing a positive transient voltage of the positive pole and a negative voltage sensor sensing a negative transient voltage of the negative pole and a control unit which is adapted to derive a DC displacement voltage from the positive and the negative transient voltages.

An output short circuit protecting device electrically connected to a power supplying device includes a first output short circuit protecting unit. The first output short circuit protecting unit includes a sensing unit, a comparing unit, a judging element, and a latching unit. The sensing unit is electrically connected to a switching unit, a first outputting resistor, and a second outputting resistor of the power supplying device. The comparing unit is electrically connected to the sensing unit. The judging element is electrically connected to the comparing unit, and a controller and a signal-controlling terminal of the power supplying device. The latching unit is electrically connected to the judging element and the signal-controlling terminal.

An electrical network is equipped with feed-in devices, loads, a distribution grid arranged therebetween, at least one semiconductor switch, and at least one electromechanical switch for separating a feed-in device or a load in the event of a fault. The feed-in devices and loads are arranged in groups which are connected together by a busbar and paired semiconductor switches. Each feed-in device and load can be separated from the grid by an electromechanical switch in the event of a fault, and the individual groups of feed-in devices and loads can be separated from one another by the semiconductor switches in the event of a fault in order to prevent cross currents on the busbar.

A method detects a working voltage collapse by use of an electric component, in which the exceeding of a critical characteristic of the working voltage is monitored and an excess is detected as a collapse. Accordingly, in order to recognize the collapse breakdown in a simple trouble-free manner, a model voltage generated by a model circuit is used as the critical characteristic.

The present invention discloses a direct-current power transmission protection device, including a resistor unit and a bidirectional circulation current switch unit, and the resistor unit and the bidirectional circulation current switch unit being connected in parallel to form the protection device, where at least one resistor is cascaded to form the resistor unit, and at least one bidirectional circulation current switch is cascaded to form the bidirectional circulation current switch unit. In addition, the present invention also provides a converter including the protection device, and at least one protection device is connected in series in each phase unit. The present invention provides the protection device, the converter and a protection method for flexible direct-current power transmission, which can rapidly and effectively suppress direct-current short circuit current and damp current oscillation, and not only can better protect equipment safety, but also can greatly shorten fault current attenuation time, thus shortening direct-current shutdown time and further decreasing economic loss and system destabilization risk caused by shutdown to the max. Moreover, the protection device is structurally simple and low in cost, and has good implementability and economic efficiency.

The direct current (DC) side fault isolator for high voltage direct current (HVDC) converters (10) includes a first set of double thyristor switches (12) connected across the line-to-line voltage terminals between first and second phases of alternating current (AC) terminals of a HVDC converter (14), and a second set of double thyristor switches (12) connected across the line-to-line voltage between the second phase and a third phase of the AC terminals of the HVDC converter (14). In use, the first and second sets of double thyristor switches (12) separate the HVDC converter (10) from an external power grid (18) during direct current (DC) side faults by turning on these thyristors (12).