This Small Business Innovation Research Phase I project will demonstrate the feasibility of developing a successful state estimation based system for fault detection, fault isolation, and service restoration in power distribution networks. Electric utilities will use the products to reduce M&O costs due to faster and more efficient responses to system outages, increase revenues and equipment utilization due to faster service restoration, and defer of capital investment due to improved reliability. The major component of the system is the three-phase Distribution System State Estimator (DSSE) which will use real-time telemetered data, forecasted data, and off-line planning data to estimate distribution system voltage magnitudes and angles, feeder flows, transformer loadings, and service load injections. The results from DSSE will provide the best estimate for the purposes of fault detection, fault isolation, and also service restoration. State-of-the-art technologies in the power system computer applications and statistics will be used in the deviation of the DSSE. The three end-use functions, fault detection, fault isolation and service restoration, will also be developed using analytical and rule-based algorithms. A special purpose measurement placement algorithm will also be developed to ensure the quality of the real-time DSSE solutions.