Sundstrand has been investigating 270-Vdc/hybrid 115-Vac electrical power generating systems (EPGS) technology in preparation for meeting the electrical power generating system (EPGS) requirements for future aircraft (1). Systems such as the one being investigated are likely to be suitable for the More-Electric Aircraft (MEA) concepts presently under industry and military study. The present Sundstrand single-channel testbed is being further expanded to better understand the electrical system performance characteristics and power quality requirements of an MEA in which traditional mechanical subsystems are replaced by those of a “more-electric” nature.This paper presents the most recent Sundstrand 270-Vdc system transient performance data, and describes the modifications being made to the 270-Vdc/hybrid 115-Vac testbed. These modifications will allow more in-depth study of power generation, control and distribution issues and enable development of MEA subsystem and component technologies. The testbed is being expanded to include: 1) two power generation and distribution channels, each rated at 120 kW; 2) two 115-Vac, 400 Hz inverters, each rated at approximately 40 kVA; 3) a Sundstrand-designed environmental control system demonstrator with a 30 kW variable speed, electrically driven centrifugal compressor and a non-azeotropic refrigerant mixture; 4) a Sundstrand-designed 5 hp electromechanical actuator (EMA); 5) a 250 kW 270-Vdc resistive loadbank; and 6) a PC-based generator/system control unit (G/SCU).