The application relates to a transmission cable joint for a medium voltage underground cable system. The cable joint comprises at least a casing and connection terminals for coupling wires of transmission cables. In addition, the connection terminals are in connection with an inductance component that is sheltered by the casing and limits capacitive earth fault current, when the coupled cables produce such current.

The application relates to a transmission cable joint for a medium voltage underground cable system. The cable joint comprises at least a casing and connection terminals for coupling wires of transmission cables. In addition, the connection terminals are in connection with an inductance component that is sheltered by the casing and limits capacitive earth fault current, when the coupled cables produce such current.

Embodiments of this application provide a power conversion circuit, a power transmission system, and a photovoltaic device. The power conversion circuit includes: a first bridge arm, where the first bridge arm includes a first upper bridge arm and a first lower bridge arm; the first upper bridge arm includes a switching component connected between an input positive end and an output end; the first lower bridge arm includes a switching component connected between the output end and an input negative end; each of the switching components includes a switching transistor and a first diode anti-parallel connected to the switching transistor.

A current command value in a period from a time when a relay switch is turned on until charging of an inverter capacitor is completed is set to a value smaller than a value corresponding to the smallest one of rated currents of components included in a circuit, and is set to a value smaller than a maximum current value in a safe operating area of a switching element.

An intelligent leakage current detection and interruption device for a power cord, including a switch module for controlling electrical connection of two power lines between input and output ends; a leakage current detection module, including two leakage current detection lines and a signal feedback line, one end of the parallelly coupled two leakage current detection lines being coupled via the signal feedback line to a point between the two power lines, for respectively detecting a leakage current on the two power lines; a detection monitoring module, coupled to the leakage current detection module, for detecting open circuit conditions in the two leakage current detection lines; and a drive module, coupled to the switch module, the leakage current detection module and the detection monitoring module, for driving the switch module to disconnect power to the output end in response to any detected leakage current or open circuit condition.

The present invention discloses a parameter tuning approach for bypass damping filter to suppress subsynchronous resonance in power systems, namely determining the parameters of capacitor, inductor and damping resistor in BDF. Using this approach, the parameters of capacitor and inductor in BDF can be adjusted, so that the frequency where the negative electrical damping of generator reaches minimum can be away from the frequency range of low frequency oscillation mode and typical frequencies of each torsional mode; the parameter of damping resistor in BDF can be further adjusted so that the minimum value of negative electrical damping is in reasonable range. The application of BDF with parameters tuned by the present invention contributes to the suppression of both the torsional interaction effect and the transient torque amplification effect.

The present invention discloses a parameter tuning approach for bypass damping filter to suppress subsynchronous resonance in power systems, namely determining the parameters of capacitor, inductor and damping resistor in BDF. Using this approach, the parameters of capacitor and inductor in BDF can be adjusted, so that the frequency where the negative electrical damping of generator reaches minimum can be away from the frequency range of low frequency oscillation mode and typical frequencies of each torsional mode; the parameter of damping resistor in BDF can be further adjusted so that the minimum value of negative electrical damping is in reasonable range. The application of BDF with parameters tuned by the present invention contributes to the suppression of both the torsional interaction effect and the transient torque amplification effect.

Novel system and methodology for adjusting a current limit threshold in a Power over Ethernet (PoE) system in accordance with requirements of a Powered Device (PD). A system for supplying power to a PD over a communications link has a requirement determining circuit for determining a PD's requirement, and a control circuit for setting a parameter restricting an output signal of the PSE in accordance with the determined PD's requirement. The control circuit may set a current limit threshold of the PSE and/or the PD in accordance with the determined PD's requirement, such as a power requirement.

Techniques are provided for non-volatile detection of an overvoltage condition in a circuit of interest. A circuit implementing the techniques according to an embodiment includes a fuse configured to provide a non-volatile indication of an overvoltage event, the indication associated with an open state of the fuse. The circuit also includes a voltage controlled current switch coupled in series to the fuse. The voltage controlled current switch is configured to enable current flow through the fuse in response to a supply voltage exceeding a threshold value associated with the overvoltage event. The current causes the fuse to switch from a closed state to an open state providing a non-volatile record of the overvoltage event. In some embodiments, the voltage controlled current switch can be a Zener diode with a breakdown voltage based on the threshold value, or a transistor configured to switch into conducting mode at the threshold value.

An electrical circuit includes a contact with a pair of switchable electrodes, the contact configured to cycle through make and break transitions while conducting current. The electrical circuit further includes an arc suppressor, at least one sensor, and a controller circuit. The arc suppressor is coupled across the pair of switchable electrodes and is to extinguish an arc formed across the pair of switchable electrodes during the make and break transitions of the contact. The at least one sensor is coupled to the pair of switchable electrodes and is configured to generate sensor data. The controller circuit includes a plurality of registers and is configured to detect a fault condition associated with the contact based on the sensor data. The controller circuit further sequences contact opening of the contact based on the detected fault condition and a timing value stored in at least one register of the plurality of registers.