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, 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: A digital protection and control device is so configured that at least parts of a digital data merging unit coupled to sensor units by a transmission medium, a protection and control unit, a communication unit for component control devices coupled to component control devices by a transmission medium, and a process bus communication unit are coupled by a parallel transmission medium, and at least a part of data exchange is based on a multimaster mode. Transmission based on the multimaster mode enables each unit to transmit/receive data independently and enables the reduction in unbalanced communication load. As a result, such a risk can be reduced that time responsiveness of operation is lowered as the entire digital protection and control device due to unbalanced concentration of data bus processing in a particular unit.

Abstract: The present invention relates to a system for protecting and controlling main-circuit components of an electricity transmission substation. The system includes devices for digital data output, protection-and-controlling, component controlling-and-monitoring, and communication. The digital data output devices input analogue AC electric values and output digital data. The protection-and-controlling devices input the data from the digital data output devices, and further control, monitor, and protect the substation main-circuit components. The component controlling-and-monitoring devices receive commands from the protection-and-controlling devices or from the substation controlling-and-monitoring equipment, and further control and monitor the substation main-circuit components. The devices for digital data output, the protection-and-controlling, and component controlling-and-monitoring are disposed near or within their corresponding substation main-circuit components.

Abstract: A digital protection and control device is so configured that at least parts of a digital data merging unit coupled to sensor units by a transmission medium, a protection and control unit, a communication unit for component control devices coupled to component control devices by a transmission medium, and a process bus communication unit are coupled by a parallel transmission medium, and at least a part of data exchange is based on a multimaster mode. Transmission based on the multimaster mode enables each unit to transmit/receive data independently and enables the reduction in unbalanced communication load. As a result, such a risk can be reduced that time responsiveness of operation is lowered as the entire digital protection and control device due to unbalanced concentration of data bus processing in a particular unit.

Abstract: A system for protecting and controlling substation main-circuit components. The system comprises: digital data output means for inputting analogue AC electric values and outputting digital data; protection-and-controlling means for inputting the data from the digital data output means, and for controlling, monitoring and protecting the substation main-circuit components; component controlling-and-monitoring means for receiving commands from the protection-and-controlling means or the substation controlling-and-monitoring equipment, and for controlling and monitoring the substation main-circuit components; and communication means. The digital data output means, the protection-and-controlling means and the component controlling-and-monitoring means are built in their corresponding substation main-circuit components.

Abstract: In differential function calculation processing, a value of differential function f(d) is calculated using differences between a plurality of predetermined number p of differential current data Dd sampled at different sampling times. The differential current data is data obtained from differential current Id or a sum of data Dj (j=1 to n where n is the number of the respective terminal currents) obtained from respective terminal currents Ipj. In restraint data calculation processing, restraint data Dr is calculated using respective terminal current data Dj sampled at the same sampling time. In restraint function calculation processing, a value of restraint function f(r) is calculated using differences between a plurality of predetermined number p of restraint data Dr sampled at different sampling times. Then, in comparison processing, the value of differential function f(d) is compared with the value of restraint function f(r).

Abstract: A protective relaying system is disclosed which detects a fault in an electric power system having a circuit breaker by using a current and a voltage of the electric power system. The protective relaying system includes an input conversion/unit adapted to receive a first and a second input signals corresponding to said current and voltage, for converting the magnitude and/or the phase of the first and second input signals to produce least two electrical quantities a first electrical quantity and a third electrical quantity, and for outputting the second input signal without conversion as a second electrical quantity.The protective relaying system also includes a comparing unit connected to receive first, second and third electrical quantities from the input conversion unit for comparing the first and second electrical quantities to produce a first logical state and comparing the third and fourth electrical quantities to produce a second logical state signal cyclically.

Abstract: A digital frequency relay for use in protecting an electrical power transmission line in the event of frequency deviations indicative of a fault condition, including an input device for receiving AC electric signals, and an oscillator for generating a reference frequency, which are connected to respective first and second counters which respectively count the number of output pulses from the oscillator during the AC electric signal positive half-cycle, and during the AC electric signal negative half-cycle. The resultant output from the first and second counters is added and compared with a set value to produce a trip signal for the frequency relay.