This SAE Aerospace Information Report defines the characteristics of a Ground Fault Protection System to be used in conjunction with 400-cycle ground power units for servicing civil aircraft. This suggested system is intended to acquaint the airlines with one system which will eliminate possible shock hazards to operating personnel.
SAE AIR769-1964 history
1973SAE AIR769-1973 Ground Fault Protection on 400-Cycle Ground Power Unit
1964SAE AIR769-1964 GROUND FAULT PROTECTION ON 400-CYCLE GROUND POWER UNITS