{HEAD ~ The power circuit} can be configured to engage {TAIL ~ a battery power supply} or an alternating current supply 
{ HEAD ~ The power circuit } can be configured to engage { TAIL ~ a battery power supply } or an alternating current supply
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH