Igumbi lokushisa eliphansi lomswakama ophezulu lifakwe isistimu yesiqandisi, isistimu yokufudumeza, isistimu yomswakama kanye nesistimu yokujikeleza.Umgomo wokusebenza uwukusebenzisa izinga lokushisa eliphansi kanye nomoya womswakama ophezulu ukuze ushaye imikhiqizo ngokufanayo.Izinga lokushisa lokuncibilika, umswakama kanye nesikhathi kulawulwa ngezigaba ngohlelo lokulawula lwe-PLC, okwenza imikhiqizo incibilikiswe ngaphansi kwemvelo ngezinga lokushisa elifanele kanye nomswakama.Igumbi lokushisa eliphansi elinomswakama ophezulu lisetshenziselwa kakhulu ukuncibilikisa inyama eyiqhwa eqinile.Uma kuqhathaniswa nezinye izindlela zokuncibilikisa, izinga lokushisa eliphansi legumbi lokuncibilikisa linokungcola okulinganayo kanye nezinga eliphansi lokulahlekelwa kwamanzi.