MAIN DC GENERATION D/O (3)GENERALThe DC main and ESSential generation consists of four identical andinterchangeable Transformer Rectifiers (TRs) and their relatedcontactors.TR1, supplied by AC BUS 1, and TR2, supplied by AC BUS 2, composethe DC main generation. These TRs respectively supply DC BUS 1 andDC BUS 2.The APU TR, supplied by AC BUS 2, is used to charge the APU BATteryand to start the APU.DC ESS network is supplied by ESS TR, which is supplied by:- AC BUS 1 in normal condition,- AC BUS 2 in abnormal condition,- EMERgency GENerator in emergency condition.Each TR contains:- a transformer part,- a rectifier part,- a monitoring card.