The reason why {TAIL ~ the maximum supply power} is different between summer and {HEAD ~ winter} is that a periodic test for the power stations is carried out in winter with less power demand in preparation for summer with more power demand 
The reason why { TAIL ~ the maximum supply power } is different between summer and { HEAD ~ winter } is that a periodic test for the power stations is carried out in winter with less power demand in preparation for summer with more power demand
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD 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