DUAL-UTILITY SYSTEM (LINEAR).
The figure shows a typical dual-utility system in linear configuration. If there is a loss of only one of the utility feeds, the system can be programmed to place that side on generator power, transfer all the loads to the remaining good utility or transfer the entire system to generator power. When the utility returns, the transfer back to utility can be open, closed or soft.
If the system is on generator power because both utilities fail and only one utility returns, the system can be programmed to return that side to utility power, return all loads to the one good utility or wait until both utilities return before automatically returning to utility power.