The Transformer Winding Deformation Tester is a specialized precision instrument used to detect whether the mechanical structure of power transformer internal windings has deformed. It mainly uses Frequency Response Analysis (FRA) or low-voltage impedance method to non-destructively determine whether the winding has faults such as distortion, bulging, displacement, or inter-turn short circuits without disassembling the transformer.
Below is a summary of core information about this instrument:
1. Working Principle
Frequency Response Analysis (FRA): This is currently the most mainstream method. The instrument injects a sinusoidal sweep signal (typically ranging from 10Hz to 10MHz) into the transformer winding and measures its response signal. Since the inductance, capacitance, and resistance of the transformer winding form a complex distributed parameter network, its frequency response characteristics (amplitude-frequency curve and phase-frequency curve) are closely related to the geometric structure of the winding.
If the winding deforms, its distributed parameters change, causing the frequency response curve to shift.
By comparing the test curve with the original factory data (longitudinal comparison) or data from other phases of the same winding/similar transformers (horizontal comparison), the degree of deformation can be determined.
Low-Voltage Impedance Method: This method assists judgment by measuring the impedance change of the winding under low voltage, often used as a supplement to FRA (according to standard DL/T 1093).
2. Main Application Scenarios
Detection after Sudden Short Circuit: After the transformer is subjected to the impact of an outgoing short-circuit current, the enormous electromagnetic force may cause winding deformation.
Transportation and Installation Inspection: After the transformer experiences severe vibration or impact during long-distance transportation or hoisting.
Periodic Preventive Tests: As part of condition-based maintenance, monitor the health status of the winding to prevent inter-turn short circuits or main insulation breakdown accidents.
Applicable Range: Typically suitable for power transformers from 63kV to 500kV and above.
3. Key Technical Indicators (Reference for 2025-2026 Mainstream Models)
According to the latest market product information, modern winding deformation testers usually have the following performance:
Sweep Frequency Range: 10Hz to 10MHz (covering low, medium, and high frequency bands).
Measurement Accuracy: Amplitude resolution can reach 0.1dB or higher, with a wide dynamic range (-120dB to +20dB).
Sampling Speed: Single-phase winding test typically takes 1-2 minutes, using high-speed A/D conversion (14-bit or 16-bit).
Anti-Interference Capability: Equipped with powerful digital filtering functions to adapt to complex on-site electromagnetic environments.
Connection Methods: Supports USB and Bluetooth wireless communication, used with laptops or tablets for analysis.
Analysis Software: Built-in intelligent diagnostic algorithms automatically calculate correlation coefficients (R), standard deviation, and other indicators, generating three-dimensional spectra.
4. Common Fault Judgment Types
Through waveform comparison, the following faults can be identified:
Axial Deformation: Compression or stretching of the winding along the core direction.
Radial Deformation: Inward depression or outward bulging of the winding.
Torsional Deformation: Spiral twisting of the entire winding.
Inter-turn Short Circuit: Short circuit caused by insulation damage of some turns.
Lead Displacement: Loosening or position change of internal leads.
5. Implementation Standards
In China, the testing and judgment of such instruments mainly follow the following power industry standards:
DL/T 911-2016 "Frequency Response Analysis Method for Power Transformer Winding Deformation"
DL/T 1093-2008 "Guide for Detection and Judgment of Power Transformer Winding Deformation by Reactance Method"
6. Mainstream Manufacturers (Reference)
There are many mature power test equipment manufacturers in China providing such instruments, for example:
Wuhan Huading Electric (HDRZ series)
Yangzhou Tuopu Electric (TP-ZKB/TP-NDBX series)
Wuhan Dingsheng Electric (DCBX series)
Wuhan Moen Intelligent (MOEORW series)
Wuhan Weian Electric (UABX series)
Usage Suggestions:
The analysis of test results highly depends on baseline data (i.e., the initial fingerprint data of the transformer after factory or overhaul). Without original data for comparison, it is difficult to make accurate judgments based on a single test. In such cases, it is usually necessary to combine horizontal comparison with transformers of the same model or mutual comparison among three phases for comprehensive evaluation.
