This cannot be permitted since it is necessary to apply {HEAD ~ a voltage} of opposite polarity to {TAIL ~ the transformer T1} to achieve demagnetization 
to
This can not be permitted since it is necessary to apply { HEAD ~ a voltage } of opposite polarity to { TAIL ~ the transformer T1 } to achieve demagnetization
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH