During power transformer working, the quality of transformer part will be decline because of electromagnetic vibration, mechanical wear, oxidize, electric corrosion, heat aging, electromagnetic power from short-circuit, breakdown from over higher voltage and other reasons from outside surroundings, even will effect the safety working of power transformer, so we need to test and maintenance transformer regularly, the time and type of maintenance will be decided by fault level, working situation and outside surroundings of power transformer, some of company making testing and maintenance work every year, some of company need temporary testing and checking, some of company just need protection maintenance for outside of power transformer, some of unite need take steel cord out of power transformer, even exchange winding line and steel cord, so the purpose of transformer checking and maintenance is to eliminate the fault, to make sure transformer in a safe and reliable working environment.
The maintenance class and period:
The maintenance of power transformer has two classes, one is big maintenance another is small maintenance, big type means to remove the steel cord out of transformer, to checking and processing of transformer body, the period of big maintenance should be in 5 years, because after transformer working for some time, the insulating parts and fixing part always loosen, after big maintenance the checking period could extend to 10years. Small type maintenance means just checking and maintenance for oil cabinet and outside accessory. Normally one time each year, the period of small maintenance should be shorten if the working environment was poor and bad.