Method for detecting and evaluating deformation of power transformer windings

The detection and evaluation methods for deformation of power transformer windings mainly include the following:

1. * * Frequency response analysis method * *:

-Principle: By scanning a generator, a set of sine wave voltages of different frequencies are applied to one end of the transformer winding, and then the voltage signals at both ends of the winding are measured and recorded. Based on these signals, the transfer function of the tested transformer winding can be obtained, and then the frequency response characteristic curve can be drawn. When the transformer winding undergoes deformation, its frequency response characteristic curve will change. By comparing and analyzing these changes, it can be determined whether the winding has undergone deformation.

-Characteristics: This method has high sensitivity and accuracy, but requires professional testing equipment and some experience.

2. * * Low voltage pulse method * *:

-Principle: The waveform changes caused by small variations in the distributed parameters within each small unit in an equivalent circuit are used to reflect changes in the winding structure. When the applied pulse wave has sufficient steepness, i.e. contains sufficient high-frequency components, these changes can be clearly reflected.

-Characteristics: This method can sensitively and accurately reflect the axial and radial deformation faults of windings, but it requires high requirements for testing instruments and equipment.

3. * * Short circuit impedance method * *:

-Principle: By measuring the short-circuit impedance of the power transformer winding and comparing it with the original impedance value, the deformation and degree of deformation of the winding can be determined based on its changes.

-Characteristics: This method has a simple testing program, good repeatability, and high reliability in evaluating deformation. However, it may not be able to detect some minor deformations.

4. * * Capacitive method * *:

-Principle: Determine whether the winding has deformed by measuring the capacitance changes between the windings of the transformer. For example, the concentrated capacitance of the low-voltage winding to ground and the capacitance between the high and low voltage windings can be measured.

-Characteristics: This method can to some extent reflect the deformation of the winding, but may be affected by other factors such as temperature, humidity, etc.

When conducting deformation detection and evaluation of power transformer windings, appropriate methods should be selected based on the actual situation. At the same time, in order to improve the accuracy and reliability of detection, multiple methods can be combined for detection and evaluation. In addition, regular preventive tests and inspections are also important measures to ensure the safe operation of power transformers.

Please note that the above methods are for reference only and not all methods are applicable to all situations. In practical applications, the most suitable method should be selected according to the specific situation, and relevant safety regulations and operating guidelines should be followed.