Common faults of power transformers: iron core faults and gas protection faults

Writer： Hengfeng you electric Time：2023-04-18 views：times

Power transformer is a static power equipment that changes the magnitude of AC voltage, and is one of the core equipment in the power system. In the process of energy transmission and distribution, power transformer is the core of energy conversion and transmission, and is a necessary path for various industries and households in the national economy to source energy.
 
 
 
01 Iron core fault
 
 
① The insulation between silicon steel sheets is damaged, causing local overheating and melting of the iron core;
 
② The insulation of the through bolt clamping the iron core is damaged, causing a short circuit between the silicon steel sheet of the iron core and the through bolt;
 
③ Residual welding slag forms a two-point grounding of the iron core;
 
④ The top and middle of the transformer oil tank, and between the upper casing flange, barrel skin and casing of the oil tank. Internal iron cores, winding clamps, and other components generate heat due to local magnetic leakage, causing insulation damage.
 
 
After the transformer malfunctions during operation, if it is determined that it is a winding or iron core fault, the core should be suspended for inspection. Firstly, measure the DC resistance of each phase winding and compare it. If the difference is significant, it indicates a winding fault. Then conduct an appearance inspection of the iron core, and measure the insulation resistance between the pieces using the DC voltage and ammeter method. If the damage is not significant, paint the damaged area.
 
02 Gas protection fault
 
Gas protection is the main protection of transformers, with light gas acting on signals and heavy gas acting on tripping. The following is an analysis of the causes and handling methods of gas protection actions:
 
 
① The reason for the gas protection action may be that the oil filtering, refueling, and cooling systems are not tight, causing air to enter the transformer;
 
② Slow decrease in oil level due to temperature drop and oil leakage; Or a small amount of gas is generated due to transformer failure;
 
③ Caused by a transient short circuit fault;
 
④ Due to secondary circuit failure of the protection device.
 
 
After the light gas protection action, a signal is issued. The reason is that there is a slight fault inside the transformer; There is air inside the transformer; Secondary circuit failure, etc. The operating personnel should immediately inspect, and if no abnormalities are found, gas sampling analysis should be conducted. When the gas protection action trips.
 
There may be serious internal faults in the transformer, causing oil to decompose into a large amount of gas, or secondary circuit faults. In case of gas protection action tripping, the backup transformer should be put into operation first, and then external inspection should be conducted. Check the explosion-proof door of the oil conservator, whether each welding joint is cracked, and whether the transformer shell is deformed; Finally, check the flammability of the gas.
 
Hengfengyou is a professional electrical company specializing in the production, manufacturing and sales of electrical distribution products, mainly engaged in the production and global sales of distribution transformers, rectifier transformers, electric furnace transformers, etc. We have provided OEM / ODM services for customers in Europe, America and the Middle East for 20 years. It can provide customized production of transformer core, transformer coil and transformer shell. Hengfengyou Electric will provide you with the best electrical product solutions. https://www.hengfengyou.com  ； info@hengfengyou.com   WhatsApp：+86158 5325 2696（Jack）    +86158 5326 5269（Alisa）