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