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