The HMG will supply DC power to the hot batt bus in one of two ways, dependant on the aircraft config and type of HMG installed.
The 5 KVA HMG incorporates a combined AC/DC generator which will supply the hot batt bus directly via a DC power relay which is controlled by the HMG GCU.
The 10 KVA HMG has an AC generator only and a dedicated TRU is installed to convert the nominal AC into DC before powering the hot batt bus.
AC buses which are supplied under HMG operation are L & R transfer and capt's instrument transfer.