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 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 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: 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: In a digital protective relay system for protecting an electric power system, a first digital operation device receives digital data on the electrical quantities of the power system and performs an operation on the digital data to produce an intermediate result, which is then stored in a memory unit. A second digital operation device reads the intermediate result from the memory unit and performs an operation on the intermediate result to produce a final result. The memory unit is so connected as to permit writing by the first operation device only, and to permit reading by the second operation device only.