Winding Deformation Tester is a device for power transformers.
Winding Deformation Tester
Winding Deformation Tester (Transformer Winding Deformation Tester) is the "orthopedic doctor" or "CT scanner" of power transformers.
Its main function is to detect whether the transformer winding (coil) has mechanical deformation, such as twisting, bulging, displacement, or inter-turn short circuit. This deformation is usually caused by transformer outlet short circuit, transportation collision, or long-term operation vibration. If not detected in time, the deformed winding may experience insulation breakdown during operation, leading to transformer explosion.
This instrument operates based on the power industry standard DL/T 911 (2004 or 2016 edition) and uses the Frequency Response Analysis (FRA) method.
⚙️ Core Working Principle: Frequency Response Analysis (FRA)
Under high-frequency signals, the transformer winding can be regarded as a complex network composed of countless resistors, inductors (L), and capacitors (C).
Fingerprint Characteristics: Each normal winding has its unique "fingerprint" — the amplitude-frequency response curve.
Deformation Means Change: When mechanical deformation (such as compression or stretching) occurs in the winding, the distributed inductance (L) and capacitance to ground (C) inside the winding change.
Detection Process:
The instrument inputs a sinusoidal sweep signal (usually from 1kHz to 2MHz) to the winding.
Measure the response voltage at the output end.
Calculate the transfer function
Plot the amplitude-frequency characteristic curve. If the positions or amplitudes of peaks and valleys on the curve significantly deviate from the original data (or among three phases), it indicates winding deformation.
Main Functions and Test Methods
The winding deformation tester mainly diagnoses faults through two comparison methods:
Table
Comparison Method Name Operation Method Applicable Scenario
Longitudinal Comparison Historical Data Comparison Overlay and compare the currently measured curve with the original curve from factory or previous test. Most accurate. Used to determine whether the same transformer has changed.
Lateral Comparison Three-Phase Comparison Compare the curve of the faulty phase (e.g., phase A) with that of a normal phase of the same type (e.g., phase B, phase C). When no original data is available. Suitable for newly commissioned transformers or those with lost archives.
