Transformer Winding Deformation Tester — Guardian of Safe Operation in Power Systems

The Transformer Winding Deformation Tester is a high-precision, intelligent testing device specifically designed for the detection of deformation in power transformer windings. Utilizing advanced Frequency Response Analysis (FRA) and Low-Voltage Short-Circuit Impedance methods, this instrument enables the rapid and accurate detection of defects—such as deformation, displacement, and inter-turn short circuits—that may occur in transformer windings during transportation, installation, or operation due to factors such as mechanical stress or electromagnetic forces. It serves as an indispensable piece of condition monitoring equipment within power systems.

Transformers are core components of any power system, and their operational status directly impacts the safety and stability of the power grid. Statistics indicate that approximately 35% of transformer failures are linked to winding deformation; if such deformation goes undetected in a timely manner, it can lead to severe consequences, including insulation breakdown, inter-turn short circuits, or even transformer explosions. This specialized testing equipment was developed precisely to address this critical issue.

Frequency Response Analysis is an internationally recognized method—and one of the most effective—for detecting deformation in transformer windings. Its fundamental principles are as follows:

1. Signal Injection: A sinusoidal swept-frequency signal (ranging from 10 Hz to 10 MHz) is injected into the transformer winding.
2. Response Acquisition: The amplitude and phase of the response signal at the winding's output terminal are measured.
3. Spectrum Analysis: A frequency response curve is plotted, and the distribution of resonance points is analyzed.
4. Comparative Diagnosis: The results are compared against historical data, data from corresponding phases, and factory test data.

• Low-Frequency Range (10 Hz – 10 kHz): Reflects changes in the overall winding structure, such as axial displacement or overall compression.
• Mid-Frequency Range (10 kHz – 500 kHz): Reflects localized winding deformation, such as displacement between winding discs or radial deformation.
• High-Frequency Range (500 kHz – 10 MHz): Reflects minute structural details within the winding, such as inter-turn short circuits or loose lead connections.

The low-voltage short-circuit impedance method assesses the condition of transformer windings by measuring changes in the transformer's short-circuit impedance:

1. A low-voltage AC signal is applied to the windings on one side of the transformer.
2. The windings on the other side are short-circuited.
3. Parameters such as voltage, current, and power are measured.
4. The short-circuit impedance is calculated and compared with historical data.

• Impedance change < 2%: Normal
• Impedance change 2%–3%: Caution
• Impedance change > 3%: Abnormal; requires further investigation

These two methods are complementary; they can be utilized independently or combined for testing, thereby significantly enhancing diagnostic accuracy.

• Supports simultaneous or independent testing of A, B, and C phase windings.
• Automatically identifies transformer connection groups (Y/Y, Y/△, △/Y, △/△, Z-type, etc.).
• All test items can be completed with a single set of connections.
• Features an automatic phase-switching function, eliminating the need for manual rewiring.

• Built-in database containing actual test data from over 5,000 transformers.
• Automatically compares historical data against current three-phase data.
• Automatically calculates the correlation coefficient (R-value).
• Graded assessment of deformation severity: R ≥ 0.95 (Normal); 0.90–0.95 (Slight Deformation); 0.85–0.90 (Moderate Deformation); < 0.85 (Severe Deformation).

• Power Transformer Factory Testing: Inspection of winding manufacturing quality; acquisition of baseline data prior to transport.
• Commissioning Tests for Newly Installed Transformers: Verification of winding condition post-installation; establishment of an initial condition baseline.
• Condition-Based Maintenance for In-Service Transformers: Periodic preventive testing; rapid diagnostics following short-circuit events.
• Pre- and Post-Overhaul Comparison: Assessment of overhaul effectiveness; verification of winding repair quality.

• High-Precision Measurement: 24-bit high-speed ADC sampling; FPGA-based digital signal processing.
• Intelligent Operation: One-touch automatic testing; voice prompts; automatic report generation.
• Standardization Compliance: Compliant with DL/T 911-2016, GB 1094.1, and IEC 60076-18 standards.
• Convenient Data Management: Cloud synchronization; trend analysis; support for integration with PMS (Power Management System).
• Comprehensive After-Sales Service: 3-year warranty; 24-hour technical support; free annual calibration.

• Background: Transformer Model SFSZ11-180000/220; short circuit occurred at the 10kV side outlet; short-circuit current: 35kA.
• Inspection Results: Phase B correlation coefficient was 0.78; assessed as having moderate deformation.
• Recommended Action: Lifted the tank cover for inspection; discovered localized bulging in the low-voltage winding; successfully returned to service after repairs.

• Background: Transport distance: 1,200 km; maximum shock acceleration experienced: 3.2g.
• Inspection Results: Correlation coefficients for all three phases were >0.95; impedance deviation was <1%.
• Conclusion: No winding deformation detected; meets the conditions for commissioning.

• Standard Configuration: Main unit, test clamps, connection cables, power cord, communication cable, ground cable, aluminum alloy carrying case, user manual.
• Optional Accessories: Extended test cables, dedicated printer, lifting platform, spare battery.