operating microscopereasons:selection ofpoweris not complete,a smallhorse-drawn carts, operating microscopemotoroverloadlongrun, the motortemperature is too high; operating microscopestartstoo frequently,a fixedshort-termorintermittentworkas asystem ofcontinuousmotor.operating microscopeshould be limited tothe number of starts,the correct selection ofthermal protection, according to themotorfixedon thecalibrationused.