The MSU (Mission Switching Unit) main function is to distribute main AC wild frequency power at the 80 KVA level from the aircraft main generators, the APU generator and the external power source to the mission loads.  The MSU utilizes a flexible software control block to route the power to the the mission Buses based on the customer's requirements. Another important function of the MSU is to monitor the power quality of the External power source and to provide a 28 VDC to interlock the external power to the mission loads.