means for opening the breaker in {HEAD ~ response} to {TAIL ~ the output signal} of the OR gate, thereby opening the breaker in response to either one of the power supply interrupting signal and the breaker opening command 
to
means for opening the breaker in { HEAD ~ response } to { TAIL ~ the output signal } of the OR gate , thereby opening the breaker in response to either one of the power supply interrupting signal and the breaker opening command
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH