a plurality of relays adapted for controlling power levels by means of controlling level combinations of said contactors, {HEAD ~ said relays} operated by {TAIL ~ means} of logic gates operating upon desired and actual power levels 
operated by
a plurality of relays adapted for controlling power levels by means of controlling level combinations of said contactors , { HEAD ~ said relays } operated by { TAIL ~ means } of logic gates operating upon desired and actual power levels
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH