1, to prevent electric shock: The power of power transformers generally comes through overhead lines, but it is vulnerable to lightning overhead lines, transformers and burned due to insulation breakdown.
2, short circuit protection to be reliable: transformer coil or load short circuit occurs, the transformer will be subjected to considerable short-circuit current, if the protection system failure or protect the value is too large, it may burn down transformer. To this end, a reliable short-circuit protection device must be installed.
3, to maintain a good grounding: use protection for low-voltage systems access to zero, the transformer low-voltage side of the neutral point to be grounded directly when the three-phase unbalanced load, the zero line will appear current. When the current is too large and the contact resistance and large, the ground will be hot, ignite surrounding combustible materials.
4, to prevent over-temperature: transformer operation should monitor temperature changes. If the transformer coil wire is A-class insulation, its insulator in paper and cotton-based, high and low temperature greatly affect the service life of the insulation and the temperature is increased by 8 ℃, insulation life to be reduced by about 50%. Transformer at normal temperature (90 ℃) operation life of about 20 years; if the temperature is raised to 105 ℃, the life of 7 years 5 temperature rose to 120 ℃, life expectancy was only two years. So transformer operation, be sure to maintain good ventilation and cooling, forced ventilation can be taken when necessary, in order to achieve the purpose of reducing the transformer temperature rise.