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.

Disclosed are advances in the arts with novel methods and apparatus for detecting faulty connections in an electrical system. Exemplary preferred embodiments include monitoring techniques and systems for monitoring signals at one or more device loads and analyzing the monitored signals for determining fault conditions at the device loads and/or at the main transmission lines. The invention preferably provides the capability to test and monitor electrical interconnections without fully activating the host system.

A power distribution system for connection to an AC voltage network, having a UPS power supply unit for uninterruptible power supply with a network-side input and with at least one output to which a number of loads are connected or can be connected in parallel load circuits, wherein a protective device having an electromechanical tripping device, in particular a thermal/magnetic tripping device, and having an evaluation and tripping unit is connected in the or each load circuit, which tripping unit trips the tripping device on the basis of an electronic overload and/or short-circuit characteristic curve and on the basis of the output voltage from the UPS power supply unit.

Disclosed are advances in the arts with novel methods and apparatus for detecting faulty connections in an electrical system. Exemplary preferred embodiments include monitoring techniques and systems for monitoring signals at one or more device loads and analyzing the monitored signals for determining fault conditions at the device loads and/or at the main transmission lines. The invention preferably provides the capability to test and monitor electrical interconnections without fully activating the host system.

Systems, devices, methods, and techniques are disclosed for performing calibrated measurements of current through switches in an electronic control unit. In one example, a device includes a current sensor system; a controller, operably connected to the current sensor system; and one or more switches, operably connected to the controller. The current sensor system is configured to receive a measurement of current conducted through at least one switch of the one or more switches. The current sensor system is further configured to perform a measurement of calibrated total current for the one or more switches. The current sensor system is further configured to determine a calibrated value of current for the at least one switch, based at least in part on a comparison of the measurement of current conducted through the at least one switch and the measurement of calibrated total current for the one or more switches.

A method and a monitoring device for selectively determining a partial system leakage capacitance in an ungrounded power supply system having a main system and at least one partial system. An extended insulation monitoring system is configured for determining an overall system leakage capacitance of the power supply system; an extended insulation fault location system for determining an ohmic and a capacitive partial test-current portion of a partial test current captured in the respective partial system; and an impedance evaluation system for determining a partial insulation resistance and a partial system leakage capacitance for each partial system to be monitored are provided. For preventing the entire ungrounded power supply system from being switched off, the fundamental idea of the present invention is advantageously based on identifying in which partial system a critical increase of a partial system leakage capacitance has taken place.

An electric propulsion system is described that includes at least one branch for distributing electrical power, provided by a power source, to one or more loads. The at least one branch is partitioned into one or more zones and comprises a plurality of branch isolation devices that are configured to isolate the at least one branch from the power source in response to a fault current at the at least one branch. In addition, the at least one branch comprises a respective pair of zone isolation devices for each respective zone from the one or more zones. The respective pair of zone isolation devices for each respective zone is configured to isolate the respective zone from the at least one branch, during a test of the at least one branch for identifying which of the one or more zones is a source of the fault current.

A selective protection circuit includes a current-limiting module and a control module, where the current-limiting module includes a switch unit, and the switch unit includes a first end, a second end, and a control end; the first end is connected to a positive electrode of a bus voltage of an HVDC power supply, and the second end is connected to a positive electrode of a power supply of a voltage pre-regulator circuit in a load branch connected to the current-limiting module; the control end is connected to the control module; and the control module is configured to output a control signal to the control end when a value of a total current flowing through the switch unit is greater than or equal to a preset threshold, so as to switch off the switch unit.

A method for identifying the type of faults occurred on a power line, characterized in that it comprises: calculating a fault point voltage on fault points based on terminal voltage and fault locations of the power line; adopting the fault point voltage corresponding to a maximum transition resistance as a setting value; comparing the fault point voltage on fault points with the setting value; and identifying the type of fault as a permanent type or a transient type based on the result of the comparison.

A method for transmitting electrical energy is proposed in which between two electrical units electrical current is transmitted by means of a superconductive cable system (4). The two ends of the superconductive cable system (4) are each connected in a current conducting manner to one of the electrical units. A normally conductive cable system. (5) is arranged parallel to the superconductive cable system (4). The function of the superconductive cable system (4) is monitored by a control unit (10). During normal operation. only one end of the normally conductive cable system (5) is connected in a voltage conducting manner to one of the electrical units. In case of a malfunction of the superconductive cable system (4), a first signal (12) of the control unit (10) initially connects the other end of the normally conductive cable system (5) to the other electrical unit, so that the normally conductive cable system (5) becomes current conducting, and the superconductive cable system (4) is subsequently switched off by at least one of the electrical units.