and the torque produced by the pmg 101 one embodiment of a pmg 101 is a general dynamics gd part number 1209 pmg the gd part number 1209 pmg 101 is a brushless and bearingless machine further the part number 1209 pmg 101 is designed in accordance with the fault tolerant architecture described herein and is constructed with windings that are electrically isolated from machine structure and from the other windings of the pmg 101 one embodiment of a pcu 102 is a general dynamics gd part number 1208 pcu and is described below the gd part number 1208 pcu 102 includes three converter modules 104 105 106 each converter module is connected a single phase of the pmg 101 through a single pair of wires the converter modules each include a transformer which is connected to an output filter 107 the output filter 107 attenuates high frequency components of the voltage that leaves the pcu 102 and is provided to the aircraft loads the voltage that leaves the part number 1208 pcu 102 is regulated to 28 5 vdc but other generator mode output voltages are possible the part number 1208 pcu 102 also includes a connection for the 28 5vdc output return current that is isolated from the pcu 102 chassis the converter modules each operate as a bidirectional converter and each provide an electrically isolated interface to the pmg 101 when the starter generator subsystem is operated as a generator the converter modules 104 105 106 convert the ac voltage from the pmg 101 to a dc voltage of the desired form when the starter generator subsystem is operated as a starter the converter.