What is transformer winding deformation?
Transformer winding deformation refers to the irreversible change in the size and shape of the winding under the action of mechanical and electrical forces. It includes changes in axial and radial dimensions, body displacement, winding twist, bulging and inter-turn shorts, etc. The reason is that the transformer is unavoidable to withstand various short-circuit shocks during operation, and the short-circuit at the outlet is particularly harmful to the transformer.
Although the circuit breaker can quickly remove the short-circuit fault from the circuit, the automatic device often does not operate for some reason, so that the transformer coil is deformed in a very short time under the action of the short-circuit current heat and electric power, and even serious It will lead to short circuit between phases and burning of windings; at the same time, the transformer may also be subjected to collision and impact during transportation and installation, resulting in distortion, broken strands, shifting, loosening and other phenomena.
What is the purpose of the transformer winding deformation test?
Answer: Winding deformation is a major hidden danger to the safe operation of power systems. In recent years, with the growth of the power system capacity, the short-circuit capacity is also increasing, and the number of winding damage accidents caused by the outlet short-circuit is also on the rise.
After the transformer winding is deformed, first, the insulation distance changes or the insulating paper is damaged. When encountering overvoltage, the winding will have inter-cake or inter-turn breakdown, or under the action of long-term working voltage, the insulation damage will gradually expand, eventually leading to the transformer. Damage: Second, after the winding is deformed, the mechanical properties decline. When the short circuit accident occurs again, an immediate damage accident will occur because it cannot withstand the huge impact force, and it can still run for a period of time.
Transformer winding deformation is one of the important reasons for transformer damage. Conventional electrical tests such as resistance measurement, transformation ratio measurement and capacitance measurement are difficult to find winding deformation, which will seriously threaten the safe operation of the power grid. For this reason, it is very necessary to test and diagnose the winding deformation of the transformer that has been subjected to mechanical force and electrodynamic force.