Thorough analysis of the causes of spontaneous combustion of power transformers
Thorough analysis of the causes of spontaneous combustion of Power Transformers
1. There is no insurance on both sides of the distribution transformer high and low voltage. Although some have been equipped with drop fuses and horn safety, the fuses are mostly replaced by aluminum or copper wire, so that when the low voltage is short-circuited or overloaded, the fuse cannot be blown normally and the transformer is burned. The high and low fuses of the distribution transformer are not properly configured. The fuse on the transformer is generally over-configured, causing the transformer to burn out when the distribution transformer is severely overloaded.
Second, due to the large number of rural lighting lines, most of them use single-phase power supply, coupled with the randomness and management of the jumper during construction, resulting in the partial phase operation of the distribution load. Long-term use causes the insulation of a phase coil to age and burn the transformer.
Third, the tap changer.
1. Adjust the tap changer privately. Due to the large difference in power load between winter and summer, the voltage changes greatly. Therefore, some rural and enterprise electricians adjust the tap changer without the test adjustment of the power repair department, causing the distribution switch to be out of position, and the contact is poor and burned.
2. The quality of the tap-changer is poor, the structure is unreasonable, the pressure is not enough, the contact is unreliable, the position of the external character wheel is not completely consistent with the actual internal position, causing the position of the star-shaped moving contact to be incomplete contact, and the misaligned moving and static contacts make The insulation distance between the two taps becomes smaller, and a short circuit or a discharge to the ground is caused by the potential between the two taps, and the short-circuit current will quickly burn the tap wire and even cause the entire winding to be damaged.
Fourth, oil seepage is the most common abnormal appearance of transformers. Since the transformer body is filled with oil, there are beads and pads at each joint to prevent oil leakage. After a long period of operation, some rubber beads and rubber pads in the transformer will be cracked and cause oil leakage, which will lead to performance degradation after the insulation is wet, short circuit and burned the transformer.
5. Most of the high and low voltage lines of the distribution transformer are introduced by overhead lines. Because the arrester is not put into operation in time or the 10kV arrester is not installed, the transformer is burned when lightning strikes.
Sixth, some distribution transformers are not equipped with first-class protection, or are equipped with a first-level protection, but their operation and reliability are extremely low, and some even cannot operate at all.