Transformer winding deformation refers to the irreversible change of the size and shape of the winding due to mechanical force and electromotive force. It includes changes in axial and radial dimensions, valve body displacement, winding distortion, bulging and inter turn short circuit. The reason is that the transformer will inevitably bear various short-circuit shocks during operation, and the outlet short-circuit is particularly harmful to the transformer.
Although the circuit breaker can quickly eliminate the short-circuit fault in the circuit, the automatic device often does not act for some reason, so that the transformer coil will deform in a short time under the action of short-circuit current heat and electromotive force, and even more serious, it will cause phase to phase short circuit and burn out the winding. At the same time, the transformer may also be impacted during transportation and installation, resulting in deformation, strand breakage, migration and loosening.
What is the purpose of transformer winding deformation test?
Winding deformation is a hidden danger for the safe operation of power system. In recent years, with the increase of power system capacity, the short-circuit capacity also increases, and the winding damage accidents after outlet short-circuit also increase.
After the transformer winding is deformed, the first is the change of insulation distance or the damage of insulating paper. In case of overvoltage, the winding will break down between cakes or turns, or the insulation damage will gradually expand under the action of long-term working voltage, resulting in Transformer Damage: second, the winding will be deformed and the mechanical properties will decline. When the short-circuit accident occurs again, it will be damaged immediately because it can not bear the huge impact, and it can run for a period of time more often.
Transformer winding deformation is one of the important causes of transformer damage accidents. It is difficult to find winding deformation in conventional electrical tests such as resistance measurement, transformation ratio measurement and capacitance measurement, which will seriously threaten the safe operation of power grid. Therefore, it is very necessary to detect and diagnose the deformation of transformer winding subjected to mechanical force and electric force.
