A system for conditioning electric power supplied from a three-phase alternating current electric power supply, including three phase lines, to a load, including the phase lines and an electric ground line, includes a plurality of first surge arresters, a plurality of second surge arresters, a plurality of third surge arresters, a three-phase surge suppressor, and a plurality of capacitors. The surge arresters minimize the amount by which the voltage between two phases and the ground line exceeds a rated value. The three-phase surge suppressor minimizes the amount by which the voltage between any of the three phases and the ground line exceeds a rated value. The capacitors minimize the amount by which the voltage between two phases falls below a rated value.

A surge protective device includes a first electrode terminal and a second electrode terminal; n gap units, connected in series between the first electrode terminal and the second electrode terminal sequentially, where a common terminal is formed between adjacent gap units; k first trigger circuits, the k first trigger circuits each include a first terminal connected to one of the common terminals, and a second terminal connected to the second electrode terminal; and m second trigger circuits, the m second trigger circuits each include a first terminal connected to one of the common terminals, and a second terminal connected to the first electrode terminal, where any one of the common terminals is connected only to either the first terminal of one of the first trigger circuits or the first terminal of one of the second trigger circuits.

A surge protective device includes a first electrode terminal and a second electrode terminal; n gap units, connected in series between the first electrode terminal and the second electrode terminal sequentially, where a common terminal is formed between adjacent gap units; k first trigger circuits, the k first trigger circuits each include a first terminal connected to one of the common terminals, and a second terminal connected to the second electrode terminal; and m second trigger circuits, the m second trigger circuits each include a first terminal connected to one of the common terminals, and a second terminal connected to the first electrode terminal, where any one of the common terminals is connected only to either the first terminal of one of the first trigger circuits or the first terminal of one of the second trigger circuits.

A method and apparatus for controlling a neutral point voltage of a three-phase resonant-earthed electric network, the apparatus including determining means configured to determine a target value for the neutral point voltage of the three-phase resonant-earthed electric network, calculating means configured to calculate at least one phase-specific control admittance or a neutral point specific control admittance required for controlling the neutral point voltage of the three-phase resonant-earthed electric network from a prevailing value to the determined target value, and admittance means configured to add the calculated at least one phase-specific control admittance between a ground and a respective phase of the three-phase resonant-earthed electric network or the calculated neutral point specific control admittance between the ground and a neutral point of the three-phase resonant-earthed electric network.

A clamping circuit employs a filter comprising two series branches of surge arresting circuits to clamp voltage spikes on equipment in series with a power transmission line. Clamping of these voltage spikes protects insulators, semiconductors, and other sensitive components within the series equipment from transient grid events. By using a predetermined frequency to control the response, the filter does not interfere with normal operation of the power system nor the operation of a power flow control module series-coupled to the transmission line through the filter. The clamping circuit employs hysteresis and imposes a shared voltage ratio between the two circuit branches, the ratio depending on frequency and voltage of the transient asserted on the transmission line, in order to provide a very sharp protection response to events within the target frequency range.

A clamping circuit employs a filter comprising two series branches of surge arresting circuits to clamp voltage spikes on equipment in series with a power transmission line. Clamping of these voltage spikes protects insulators, semiconductors, and other sensitive components within the series equipment from transient grid events. By using a predetermined frequency to control the response, the filter does not interfere with normal operation of the power system nor the operation of a power flow control module series-coupled to the transmission line through the filter. The clamping circuit employs hysteresis and imposes a shared voltage ratio between the two circuit branches, the ratio depending on frequency and voltage of the transient asserted on the transmission line, in order to provide a very sharp protection response to events within the target frequency range.

In one embodiment, and apparatus includes an electrical socket for connection with an electrical plug, a sensor for identifying a secure connection between the electrical socket and the electrical plug, and an electronic controller electrically coupled to the electrical socket and comprising a power input for receiving power. The electronic controller is operable to transmit power to the electrical socket upon receiving a signal from the sensor identifying the secure connection between the electrical socket and the electrical plug and shut off or turn on power to the electrical socket upon receiving an external input to the electronic controller. A method is also disclosed herein. The apparatus and method provide an electronic controlled power switch or circuit breaker safety device.

In one aspect, the application provides an electrical system including a conductor, a ground, an arrester electrically connected to the conductor, and a disconnector assembly electrically connected between the arrester and the ground. The disconnector assembly includes an isolator configured to perform an operating function in response to the occurrence of an event and a housing configured to surround the isolator. The isolator includes a first terminal electrically connected to the arrester by a first wire and a second terminal electrically connected to the ground by a second wire. The housing includes a first opening through which the first terminal extends, a second opening through which the second terminal extends, and a retention mechanism configured to hold the isolator in place relative to the arrester.

An apparatus includes a surge protection device, a current sensor configured to sense a current through the surge protection device, and a surge discriminator circuit coupled to the current sensor and configured to discriminate among a plurality of surge levels for the surge protective device responsive to the sensed current. The current sensor may include a current transformer configured to generate a secondary current responsive to the sensed current and the surge discriminator circuit may be configured to discriminate among a plurality of surge levels responsive to the generated secondary current.

Methods and apparatus provide for a primary side circuit including one or more voltage nodes; and a monitoring circuit operating to monitor one or more parameters of the primary side circuit, and including at least one sensing circuit and at least one processing circuit within a secondary side circuit, where the sensing circuit includes a resistor network having an input for receiving a first sensed voltage from a first of the voltage nodes of the primary side circuit, traversing an isolation boundary between the primary side circuit and the secondary side circuit while adhering to a safety specification, which includes a primary-secondary isolation requirement, and having an output for providing a first modified sensed voltage to the processing circuit.