Abstract: According to one embodiment, a current input converter includes a first metal plate having a solid shape, which has one end attached to the terminal table and one other end attached to one end of a primary-side coil of the transformer, and connects the terminal table and the one end of the primary-side coil of the transformer to each other, and a second metal plate having a solid shape, which has one end attached to the terminal table and one other end attached to one other end of the primary-side coil of the transformer, and connects the terminal table and the other end of the primary-side coil of the transformer to each other.

Abstract: According to one embodiment, there is provided a protection relay. The protection relay includes an input circuit that detects a state of an external device according to whether or not an external input voltage is larger than a preset threshold voltage. The input circuit includes switching unit that is made conductive by a divided voltage obtained by voltage-dividing resistors that divide the external input voltage when the external input voltage is higher than or equal to the threshold voltage, and a photocoupler that is operated by a constant current of a constant current output circuit supplying a constant current and outputs an operation signal to the operation unit when the switching unit is made conductive.

Abstract: According to one embodiment, a current input converter includes a first metal plate having a solid shape, which has one end attached to the terminal table and one other end attached to one end of a primary-side coil of the transformer, and connects the terminal table and the one end of the primary-side coil of the transformer to each other, and a second metal plate having a solid shape, which has one end attached to the terminal table and one other end attached to one other end of the primary-side coil of the transformer, and connects the terminal table and the other end of the primary-side coil of the transformer to each other.

Abstract: According to one embodiment, there is provided a protection relay. The protection relay includes an input circuit that detects a state of an external device according to whether or not an external input voltage is larger than a preset threshold voltage. The input circuit includes switching unit that is made conductive by a divided voltage obtained by voltage-dividing resistors that divide the external input voltage when the external input voltage is higher than or equal to the threshold voltage, and a photocoupler that is operated by a constant current of a constant current output circuit supplying a constant current and outputs an operation signal to the operation unit when the switching unit is made conductive.

Abstract: A current differential relay device is described. The device has two transmission parts provided in parallel and communicating with an other end of a power transmission line through two transmission paths and transmitting and receiving a quantity data of electricity of each of the terminals to and from an other end in the form of the digital data obtained through analog/digital conversion. Two current differential operation parts are connected to each of the two transmission parts and perform a current differential operation independently for each of the transmission paths by using the digital data of the quantity data of electricity of the one end of the power transmission line and of the other end of the power transmission line. A signal generation part generates a trip signal from the current differential operation result of the two current differential operation parts.

Abstract: Two current differential relay devices 1 are installed at each terminal 3 of a two-terminal power transmission line 2, and connected to each other via two transmission paths 5 and 6, and perform current differential operations by transmitting and receiving the quantity data of electricity to each other. In the current differential relay device 1, two transmission means 14 normally each perform communications with the current differential relay device 1 of the other end of the power transmission line in parallel through the two transmission paths 5 and 6. Two current differential operation means 14 are connected to the two transmission means 14 respectively and perform independently two-series of current differential operations independently for each series associated with each of the transmission paths 5 and 6.

Abstract: In a digital protection relay with a time sync function, the sampling timing of which is specified based on a reference timing transmitted from a time signal generator to a time sync unit, with a determination value. The time sync unit includes a reception circuit that receives a discrimination code and time data transmitted from the time signal generator, a code discrimination circuit that discriminates the reference timing on condition that the received discrimination code coincides with a desired code, a time calculation circuit that calculates the sampling timing on the basis of the discriminated reference timing and the time data, and a sampling sync circuit that specifies the sampling timing of a digital quantity of electricity on the basis of the calculated sampling timing.

Abstract: A time synchronization system comprises a GPS (Global Positioning System) receiver for receiving a time signal from a Global Positioning System (GPS), and outputting a UTC (Universal Time Coordinated) synchronization reference signal synchronizing with UTC and a UTC synchronization absolute time signal, and a time signal distributor for generating a reference time signal synchronizing with UTC from the synchronization reference signal and the absolute time signal, and transmits this reference time signal in distribution to a plurality of distributed control oriented terminal devices. The time synchronization between the plurality of distributed control oriented terminal devices can be thereby taken.

Abstract: In transmitting signals to an opposing terminal by introducing a system current from a terminal of this side, a dummy bit interpolator (105) is provided for inserting dummy bits among the fixed frame lengths of the transmission signals to adjust the length of the transmission data by using dummy bits in order to maintain synchronism in the sampling timings even when there does not hold a multiple relationship between the sampling frequency and the rate of transmission.

Abstract: In a digital protection relay with a time sync function, the sampling timing of which is specified based on a reference timing transmitted from a time signal generator to time sync means, with a determination value, the time sync means includes a reception circuit that receives a discrimination code and time data transmitted from the time signal generator, a code discrimination circuit that discriminates the reference timing on condition that the received discrimination code coincides with a desired code, a time calculation circuit that calculates the sampling timing on the basis of the discriminated reference timing and the time data, and a sampling sync circuit that specifies the sampling timing of a digital quantity of electricity on the basis of the calculated sampling timing.

Abstract: A digital protective relay comprises a protective relay arithmetic processing unit for judging, based on a relay judgement quantity obtained by converting a system electric quantity into a digital value, whether in an operating state or in a non-operating state, and a time synchronizing unit for inputting a time reference signal from outside and synchronizing an internal timer of the digital protective relay with an external reference time. The time synchronizing unit includes an A/D converting unit for A/D converting the time reference signal inputted from outside with a resolution of at least 2 bits, and a decoding unit for decoding a time code signal by making a judgement as to a magnitude of the time reference signal with respect to a digital value obtained by the A/D converting unit.

Abstract: A digital protective relay system is capable of making sampling timing the same among plural protective relay device which operate independent from each other by using a signal from a GPS satellite. The sampling timing is made the same regardless of the time lag from which it is sent downstream with the concomitant transmission delay time in the case of data communications, or regardless of the time lag from which it is sent upstream.

Abstract: A short-circuit distance relay has a short-circuit distance relay element that calculates a fault impedance from voltage and current which are introduced from a power system and that compares the fault impedance with a set impedance and uses the fault impedance comparison result within its protection zone. It calculates the amplitudes of the phase-to-phase differences of these voltage amplitudes and a sensitivity constant Vk.

Abstract: A digital protective relay system is capable of making sampling timing the same among plural protective relay device which operate independent from each other by using a signal from a GPS satellite. The sampling timing is made the same regardless of the time lag from which it is sent downstream with the concomitant transmission delay time in the case of data communications, or regardless of the time lag from which it is sent upstream.

Abstract: A time synchronization system comprises a GPS (Global Positioning System) receiver for receiving a time signal from a Global Positioning System (GPS), and outputting a UTC (Universal Time Coordinated) synchronization reference signal synchronizing with UTC and a UTC synchronization absolute time signal, and a time signal distributor for generating a reference time signal synchronizing with UTC from the synchronization reference signal and the absolute time signal, and transmits this reference time signal in distribution to a plurality of distributed control oriented terminal devices. The time synchronization between the plurality of distributed control oriented terminal devices can be thereby taken.