Power Transformer Winding Deformation Tester
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Product Introduction
◆ The acquisition control adopts a high-speed, highly integrated microprocessor.
◆ USB communication interface between PC and instrument.
◆ The hardware core uses DDS dedicated digital high-speed frequency sweep technology (USA). Through testing, it can accurately diagnose faults such as winding distortion, bulging, displacement, tilting, inter-turn short circuit deformation, and phase-to-phase short circuit.
◆ High-resolution dB value measurement, dual-channel 16-bit A/D (changing the tap changer during field test results in obvious output changes).
◆ The signal output amplitude can be adjusted by software, with a maximum amplitude of ±10V.
◆ The computer generates an electronic document (WORD) of the test results.
◆ Using precision, high-stability components, repeated tests on the same phase yield a measurement repeatability rate of over 99.5%.
◆ The finished circuit board has a special surface treatment, resistant to water and harmful gas pollution.
◆ The laptop and measuring instrument are powered by isolated power supplies to eliminate external interference.
◆ The instrument has dual measurement system functions: linear frequency sweep measurement and segmented frequency sweep measurement, compatible with the two current domestic technical schools of measurement modes.
◆ The amplitude-frequency characteristics meet the national technical indicators for amplitude-frequency characteristic testers. The horizontal axis (frequency) has both linear and logarithmic scales, so the printed curve can be either linear or logarithmic, depending on user needs.
◆ Automatic analysis system for test data, horizontal comparison of winding similarity among phases A, B, and C, with results: ①Very good consistency ②Good consistency ③Poor consistency ④Very poor consistency. Vertical comparison of A-A, B-B, C-C by retrieving original data and comparing with current data for the same phase to assess winding deformation, with results: ①Normal winding ②Mild deformation ③Moderate deformation ④Severe deformation.
◆ Automatically generates Word electronic documents for storage and printing.
◆ Fully meets the technical conditions of the power standard DL/T911-2004 "Frequency Response Analysis Method for Power Transformer Winding Deformation".
Scanning modes: (The instrument has dual measurement systems: linear frequency sweep and segmented frequency sweep)
(1) Linear sweep distribution
Sweep frequency range: (1kHz)-(2MHz), 2000 sweep points, resolution 1kHz
(2) Segmented sweep distribution
Sweep frequency range: (0.5kHz)-(1MHz), 2000 sweep points;
(0.5kHz)-(10kHz), resolution 0.02kHz
(10kHz)-(100kHz), resolution 0.2kHz
(100kHz)-(500kHz), resolution 1kHz
(500kHz)-(1000kHz), resolution 1kHz
Other technical parameters:
◆ Amplitude measurement range: (-100dB) to (+20dB)
◆ Amplitude measurement accuracy: 0.1dB
◆ Sweep frequency accuracy: less than 0.01%
◆ Signal input impedance: 1MΩ
◆ Signal output impedance: 50Ω
◆ Same-phase test repeatability: 99.5%
◆ Measuring instrument dimensions (length×width×height): 345×250×120 (mm)
◆ Instrument aluminum alloy case dimensions (length×width×height): 425×335×215 (mm)
◆ Instrument accessory aluminum case dimensions (length×width×height): 425×335×150 (mm)
◆ Total weight: 10Kg
Detailed Introduction
The power transformer winding deformation tester, based on the measurement of internal winding characteristic parameters of the transformer, adopts the internal fault frequency response analysis (FRA) method currently being developed and perfected in developed countries, enabling accurate judgment of internal transformer faults.
After the transformer design and manufacturing are completed, its coils and internal structure are determined. Therefore, for a multi-winding transformer coil, if the voltage levels are the same and the winding method is the same, the corresponding parameters (Ci, Li) of each coil should be determined. Thus, the frequency domain characteristic response of each coil is also determined, and the frequency spectra of the corresponding three-phase coils have a certain comparability.
During the test, if inter-turn or phase-to-phase short circuits occur, or if the transformer suffers impact during transportation causing coil displacement, or if electromagnetic forces during short circuits and fault conditions cause coil deformation during operation, the distributed parameters of the transformer winding will change. This in turn affects and alters the original frequency domain characteristics of the transformer, i.e., changes in amplitude and resonance frequency shifts in the frequency response. The HX021 transformer winding frequency response tester, developed based on the response analysis method, is a novel non-destructive testing device for internal transformer faults. It is suitable for detecting internal structural faults in 63kV to 500kV power transformers.
The transformer winding deformation frequency response tester quantifies the response changes of internal winding parameters in different frequency domains. Based on the magnitude of change, the amplitude and region of frequency response change, and the trend of frequency response change, it determines the degree of internal winding deformation. This allows judgment of whether the transformer has been severely damaged and whether major repair is needed.
For transformers in operation, even if no previous frequency domain characteristic graphs are saved, the degree of fault can be judged by comparing the characteristic spectra of the faulty transformer coils. Of course, if a set of original winding characteristic graphs is available, it provides a stronger basis for analyzing the transformer's operating condition, post-accident analysis, and maintenance.
The transformer winding deformation frequency response tester consists of a laptop and a microcontroller forming a high-precision measurement system. It is compact, easy to operate, and has relatively complete testing and analysis functions. It can be operated by following the user manual or after short-term training.
