The Rocketdyne Division of Rockwell International Corporation is currently researching and evaluating the use of Artificial Intelligence and in particular Expert System technologies for the monitoring of large space-based electric power systems such as NASA's Space Station Freedom (SSF).Power System Security of space borne and lunar based electrical power systems provide unique challenges to power system software design engineers. The major responsibility of Power System Security is the monitoring of the state of health of the Power Distribution System. The role of system security is to ensure that uninterrupted electrical power of high quality is distributed to all the load centers . Voltage, current, power source reliability, and power quality are main components that describe the integrity of an electrical power system and fall into the area of security control. Because of the nature of space based power systems, their remote locations and limited power generating capability, security control becomes a major issue. One area of practical research is the use of knowledge base technologies to filter incoming telemetry data in ground support centers. Ground support personnel are dependent on telemetry data as their only window into the performance of the power system at any given time. Extracting useful information from incoming sensor data is of prime importance. Based on an already existing experience base with terrestrial power facilities, methodologies for performing non-routine procedures such as health monitoring can be applied to these space and lunar based power systems. One health monitoring procedure vital to earth based power systems is the analysis of analog measurement discrepancies. Analog measurement discrepancies occur in power distribution networks as a result of several factors including; leakage currents due to grounding faults, instrumentation drifts and failures due to faulty transducers and short circuits.This paper reports on the work Rocketdyne is performing in the area of Power System Security Monitoring. A description of IPAC (Integrated Power Advisory Controller) which represents a portion of a ground based system security monitor is presented along with a discussion of the simulation environment used for developing and testing the system.