By this, unnecessary frequent swiveling of {HEAD ~ the nacelle} is avoided and also a large amount of electricity for swiveling {TAIL ~ the nacelle} is saved 
By this , unnecessary frequent swiveling of { HEAD ~ the nacelle } is avoided and also a large amount of electricity for swiveling { TAIL ~ the nacelle } is saved
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH