Protection of dry - type transformers

According to the use of environmental characteristics and protection requirements, 3 phase step up transformer can choose a different shell. Usually IP20 protective shell, to prevent the solid foreign body greater than 12mm in diameter and rats, snakes, cats, birds and other small animals to enter, resulting in a short-circuit power failure and other malignant failure, to provide security for the live part of the barrier. If you need to install the transformer in the outdoors, you can choose IP23 protective shell, in addition to the IP20 protection, but also to prevent the vertical line into a 60 ° angle within the water droplets into. But the IP23 shell will reduce the cooling capacity of the transformer, the choice should pay attention to its operating capacity to reduce.

A thorough analysis of the cause of spontaneous combustion of power

First, the prefabricated compact transformer high and low voltage on both sides without insurance. Although some have been fitted with drop-out fuse and claw insurance, but its fuse is used more aluminum or copper wire instead, resulting in low-voltage short-circuit or overload, the fuse can not fuse and burn the transformer. Distribution transformer high and low fuse configuration properly. Transformer fuses on the widespread configuration of the phenomenon is too large, resulting in a serious overload distribution transformer when the transformer burned.
Second, the rural lighting lines are more, most of them are using single-phase power supply, coupled with the construction of the jumpers in the random and management is not in place, resulting in a partial load shifting phase of operation. Long-term use, resulting in a phase coil insulation burned the aging transformer.
Third, the tap.
1, privately adjust the tap. As the winter and summer load differences in electricity consumption, the voltage level of change. Thus some rural and corporate electrician without electric repair department to adjust the trial and adjust the tap changer privately, resulting in distribution transformer tap-changer is not in place, bad contact and burned.
2, the tap switch poor quality, irrational structure, the pressure is not enough, contact is not reliable, the external character wheel position and the actual position is not exactly the same, causing the star moving contact position is not fully contact, dislocation of the dynamic and static contact The insulation distance between the two taps becomes small and short-circuit or ground discharge occurs under the action of the potential between the two taps. The short-circuit current will soon burn the taps and even damage the whole winding.
Fourth, oil leakage is the transformer most common appearance anomalies. As the transformer body filled with oil, the connection parts are rubber beads, pads to prevent oil leakage. After a long period of operation, will make some of the rubber beads in the transformer, rubber pad aging caused by oil seepage cracks, resulting in decreased performance after damp insulation, discharge short circuit, burn the transformer.
Fifth, the single phase pole mounted transformers high and low voltage lines are mostly introduced by the overhead lines, lightning arrester is not put into operation in time or without the installation of 10kV surge arresters, resulting in lightning destroyed the transformer.
6, some of the distribution transformer is not configured a protection, or is configured with a protection, but its action, reliability is very low, and some can not even action.