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Failure Analysis Of Transformer In Power System
- Nov 09, 2017 -

Transformer is a device, using the principle of electromagnetic induction to change the current transformer in the power system has a very wide range of USES, through experiment and investigation confirmed that the transformer caused by short circuit fault has been seriously affects the safety and stability of the power transmission, so in order to reduce the fault probability of power system, you need to focus on analysis of transformer short circuit capacity study.


The reasons for the short-circuit accident of transformer are analyzed.

1. Defect of transformer structure design

Due to the defects in the structure design, the transformer has been directly determined by its weak anti-short-circuit capability.Transformer in our country at present stage, manufacturers use static theory for transformer mechanical force calculation, calculated by the static theory shows copper wires transformer if wire stress is less than 1600 kg/cm2, but in actual use process, transformer internal dynamics is a complex and changeful process, the common theoretical value was not intuitive reflect the actual operation condition of transformer, so it is difficult to meet the needs of anti-short circuit ability.From the current relatively common transformer model analysis, low loss transformer is still the mainstream product.But how to realize the low loss of transformer, different manufacturers have not formed a consensus.In addition, in the large capacity transformer low-voltage fuses in design link, if the fuse protection leads to the formation of a low-pressure lead cantilever beam are not fully considered, once encountered the impact of short-circuit current, and the result will be a short circuit fault.


2. The material quality is not passed

Transformer insulation press, laminated wood processing quality and mechanical strength do not meet the standard requirements, also can cause short-circuit fault frequent phenomenon.Some transformer manufacturers, in order to maximize reduce the wastage of the winding eddy current, and processing difficulty and reduce production costs, often in the design process, use the thickness of thin wires or ordinary cheap transposed conductor mechanical properties rather than the stronger half hard wire, although these ordinary cheap materials can help enterprises to reduce production costs, but is limited by the performance of the material itself, can't satisfy the anti-short circuit ability of transformer winding.Moreover due to the different levels of the current domestic production manufacturers, production technology and some advanced foreign technology there is a big gap, so that the density of insulation board is not enough, lead to shrinking natural phenomena are likely to cause a transformer short-circuit fault.


3. There are serious structural problems

Transformer can also cause serious problems in terms of structure, fault, due to the transformer from the manufacturing factory to be put into use after a series of transportation, assembly and disassembly, and therefore will inevitably be some impact.If the internal structure of the transformer is not strong, the structure of the winding displacement and insulation damage will be caused by the impact of the impact, which will be a huge safety hazard for future operation.


4. The problem of transformer running in 220kv environment

For the 220kv large-capacity transformer, the connection condition of inner ring is also an important determinant of short circuit fault.Although the inner ring with tapping can provide a lot of convenience for the operation of the large capacity transformer, but if the tap design is not reasonable, lead to tap the local electric field disturbance, lead the transformer partial discharge.


5. Problems in process and equipment

The manufacturing process and equipment of the transformer can also cause the failure of the resistance to short circuit when the coil is tight, tight and tight.And the insulating pad of the transformer is not sealed, or the processing work is not in place. It is possible that the electric power generated by the short circuit will cause the conductor to be broken through the insulation damage.


In winding of transformer coil, wire tension is not enough or is limited by technology and equipment, coil winding will form a dangling loose phenomenon, reduce the transformer anti-short circuit ability, coil s place tie close enough strong and easy to cause short circuit fault of transformer.If the clearance of the coil is too large, the inner support of the coil is not enough to cause the winding coils to deform or collapse, thus posing a great safety hazard to the future operation.Another transformer core clamping force is not enough, in the core after overstow no effective measurement as well as to an appropriate adjustment of the pressure, also can cause core clamping imprecise, prone to displacement of the transportation collision, transformer internal stress non-uniform cause serious consequences.