System Analysis and Application Concerning with Single Phase Spot Network (SNW)

Household use of microcomputer-based equipment now requires that the power supply to dwellings be highly reliable without momentary failures. Three-phase power supply networks have previously been used to distribute single-phase loads to dwellings. Single-phase networks have a better cost performance compared with the three-phase network system. However, due to the complicated current analysis in the case of faults and to the difficulty in developing relays based on the analytical results, single-phase networks have not yet been put into practical use. We have now succeeded in developing a single-phase network using the following five processes: (1) System analysis (2) Verification using a simulated circuit (3) Determination of the relay characteristics based on the analytical results (4) Development of a static single-phase network relay to satisfy with the complicated voltage-current relationship (5) Actual field test This system has been operating since 1983.