However, when {HEAD ~ the number} of primary windings of the main transformer is increased to form {TAIL ~ two parallel primary windings}, for example, two inverter output cables for each round trip, that is, a total of four cables are required 
is increased to form
However , when { HEAD ~ the number } of primary windings of the main transformer is increased to form { TAIL ~ two parallel primary windings } , for example , two inverter output cables for each round trip , that is , a total of four cables are required
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL 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