A current differential relay apparatus includes a first relay and a second relay. The first relay calculates a first differential current and a first suppression current, using a first current and a second current, and performs a ratio differential relay operation based on the first differential current and the first suppression current. The second relay calculates a maximum of results of add operations of the first current and the second current as a second differential current, calculates an add operation of the maximum of the first current and a maximum of the second current as a second suppression current, and performs a ratio differential relay operation based on the second differential current and the second suppression current. The current differential relay apparatus includes an output controller that outputs an operation signal based on results of operations performed by the first and second relays.

A current differential protection method for a self-adaptive half-wavelength line based on a time-difference method. Since an electrical distance of half-wavelength power transmission is long, after a fault occurs, there is an obvious time difference between the actuation times for protecting starting elements at two sides of a line. According to the principles of wave propagation, the position of a fault point can be determined by means of a difference between the actuation times for protecting the starting elements at the two sides of the line. By means of taking the fault point as a differential point, a current value at the differential point can be obtained according to a long line equation by means of the voltage and current at protection-mounted positions at the two sides of the line, and a differential current is then calculated.

A control method allows the control of an installation for transmitting electricity comprising a DC transmission network including a group of electricity transmission lines that are linked to one another. The method allows the opening of at least one N-1 safety system, for each safety system being opened, the contribution to the flow of current through the group of transmission lines, originating from the converter station associated with the safety system that is opened, is removed. Furthermore, the method also allows a search for the short-circuit fault in order to identify the faulty transmission line, and an operation, implemented after identification of the faulty transmission line by the search step, of isolating the faulty transmission line by opening the line circuit breakers of the faulty transmission line.

A method detects a fault on a line of an electrical power supply system, in which current values are measured at the line ends of the line and the current values are used to check whether there is a fault on the line. In order to perform monitoring of the line such that faults can be detected comparatively quickly and sensitively, it is proposed that voltage values are also measured at the line ends. The respective measured current and voltage values are used to ascertain respective comparison current values indicating the current flowing at a comparison location on the line and the respective comparison current values are used to check for the presence of a fault on the line, and a fault signal is generated if the check has resulted in a fault present on the line being detected.

In a protective relay device, a current differential relay computation unit determines whether or not a fault has occurred within a protected section based on an operating quantity and a restraint quantity. A disconnection detection unit computes a first amount of difference by subtracting the operating quantity a certain time period ago from the operating quantity at a present point in time, computes a second amount of difference by subtracting the restraint quantity the certain time period ago from the restraint quantity at the present point in time, and determines that a disconnection has occurred at one of first and second current transformers when a first determination condition that an absolute value of a sum of the first amount of difference and the second amount of difference is equal to or smaller than a first set value is satisfied.

A squib driver circuit for deployment of an active safety restraint in a vehicle. The squib driver circuit may include a high side protection circuit. The high side protection circuit may include a comparator circuit to compare the input voltage to a reference voltage and activate a timer in response to the input voltage exceeding the reference voltage, the timer generating a disable signal to disable the high side driver after a predetermined period of time The high side protection circuit may disable the high side driver after a short is detected and elapse of the predetermined period of time. The squib driver circuit may be formed on a single chip.

A squib driver circuit for deployment of an active safety restraint in a vehicle. The squib driver circuit may include a high side protection circuit. The high side protection circuit may include a comparator circuit to compare a voltage at a high side feed terminal to a reference voltage and activate a timer in response to the voltage at the high side feed terminal exceeding the reference voltage, the timer generating a disable signal to disable the high side driver after a predetermined period of time. The high side protection circuit may disable the high side driver after the short is detected and elapse of the predetermined period of time. The squib driver circuit may be formed on a single chip.

An over-current protection apparatus constituted of: a transistor disposed on a substrate; a first thermal sense device arranged to sense a temperature reflective of a junction temperature of the transistor; a second thermal sense device arranged to sense a temperature reflective of a temperature of a casing surrounding the substrate; and a control circuitry, arranged to alternately: responsive to the sensed temperature by the first thermal sense device and the sensed temperature of the second thermal sense device being indicative that the temperature difference between the transistor junction and the substrate casing is greater than a predetermined value, switch off the transistor; and responsive to the sensed temperature by the first thermal sense device and the sensed temperature by the second thermal sense device being indicative that the temperature difference between the transistor junction and the substrate casing is not greater than the predetermined value, switch on the transistor.

There is provided mechanisms for phase selection using multi-terminal measurements of a transmission line of a power system. A method comprises obtaining, using measurements from at least two terminals of the transmission line, delta differential current values I.sub.diffA(t), I.sub.diffB(t), I.sub.diffC(t) at time t between pre-fault differential current measurements and post-fault differential current measurements from all phases A, B, C of the transmission line. The method comprises determining the phase A, B, or C to be faulty when the absolute value of the corresponding delta differential current value is larger than k times the minimum of all the absolute values |I.sub.diffA(t)|, |I.sub.diffB(t)|, |I.sub.diffC(t)| of the delta differential current values, where k>1 is a scale factor.

A photovoltaic power generation system includes a plurality of photovoltaic arrays, a plurality of shutdown units and an inverter. The shutdown unit is adjacent to the corresponding photovoltaic array, connected in parallel with the corresponding photovoltaic array, and electrically connected to the inverter via high voltage wires; the photovoltaic power generation system further includes a control unit configured to receive a detection signal indicating a state of the AC side of the inverter, monitor whether the AC side of the inverter is in a power-off state according to the detection signal, and generate a first power-off signal when the AC side of the inverter is in the power-off state; and the shutdown units are configured to receive the first power-off signal, and stop a power transmission from the photovoltaic arrays to the inverter according to the first power-off signal.