Apparatus for interrupting {HEAD ~ supply} of power from power system to portion of consumer load in {TAIL ~ response} to control signal from power system 
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Apparatus for interrupting { HEAD ~ supply } of power from power system to portion of consumer load in { TAIL ~ response } to control signal from power system
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH