Diode protection 512, e.g., crossed diodes connected in parallel with one another and with {HEAD ~ a resistor element} may be connected across {TAIL ~ pairs} of conductors in each circuit 
Diode protection 512 , e.g. , crossed diodes connected in parallel with one another and with { HEAD ~ a resistor element } may be connected across { TAIL ~ pairs } of conductors in each circuit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH