Winding Deformation Tester
The Transformer Winding Deformation Tester (Frequency Response Analysis, FRA) is a core device for diagnosing the health of the transformer's "heart." It is mainly used to detect whether the windings of power transformers of 6kV and above have undergone mechanical deformation such as twisting, bulging, or displacement after short-circuit impacts or transportation collisions, enabling rapid judgment without removing the tank.
The following is a practical procurement guide combined with the latest 2026 industry standards:
I. Core Selection Parameters: 6 Hard Indicators That Must Be Checked
1. Frequency Sweep Range and Frequency Accuracy
Frequency sweep range: Should cover 1kHz–2MHz, with high-end models extending to 10Hz–10MHz. The wider the range, the better it can capture deformation characteristics in different frequency bands (low frequency reflects overall deformation, mid frequency reflects local bulging, high frequency reflects inter-turn/lead displacement).
Frequency accuracy: Requires ≤0.01% (some high-end models reach 0.001%), which is the basis for ensuring curve repeatability and comparison validity.
2. Dynamic Range and Amplitude Accuracy
Dynamic range: Recommended ≥-100dB to +20dB, with high-end models reaching -120dB to +20dB. The larger the dynamic range, the better it can capture weak signal changes to identify minor deformation.
Amplitude accuracy: Should be controlled within ±0.5dB (some reach 0.1dB), reducing the interference of system errors on diagnostic conclusions.
3. Test Repeatability
For multiple measurements of the same winding, curve coincidence should be ≥99.5% (high-end models reach 99.9%). High repeatability is the prerequisite for eliminating external interference such as wiring and grounding and confirming true deformation.
4. Impedance Matching
Output impedance: Must be 50Ω (matching the characteristic impedance of power cables)
Input impedance: ≥1MΩ (the response channel has a built-in 50Ω matching resistor)
5. Dual Test Modes — A Bonus Feature
Prefer a comprehensive tester that supports both Frequency Response Analysis (FRA) + Low Voltage Impedance method. The frequency response method has high sensitivity but requires baseline comparison, while the impedance method can be quantitative but has lower sensitivity. Their complementarity can greatly improve diagnostic accuracy.
6. Compliance Certification
Must comply with DL/T 911-2016 (frequency response method) and DL/T 1093-2008 (impedance method) standards, and should be accompanied by third-party verification/calibration certificates from metrology institutes or electric science research institutes at or above the provincial level.
II. Recommended Mainstream Brands and Models
High-quality Domestic Brands (mainly in the Wuhan/Jiangsu industrial belts)
Brand Representative Model Core Advantages Application Scenarios
Wuhan Huayi Electric Power RBX Series Dual-method integration (FRA + impedance), 20Hz-10MHz wideband, -120dB dynamic range, IP54 protection Preventive testing for State Grid substations
Wuhan Sanxin Electric Power — Complete product line, cooperation with Huazhong University of Science and Technology, providing one-stop comprehensive transformer testing solutions Factory acceptance testing for transformer manufacturers
Wuhan UHV — 1kHz-2MHz frequency band, 1Hz resolution, built-in 100+ winding parameter templates, strong anti-interference Operation and maintenance of box-type substations at new energy stations
Wuhan Zhongneng Xinyi ZNRZ-II Dual-channel synchronous sampling, built-in 128 FRA template libraries, verified for 3+ years at 32 220kV stations Provincial electric science research institutes/large power generation groups
Wuhan Huaneng Lianchuang HNLC-801 Whole machine 7.3kg, IP54, Bluetooth 5.0 mobile APP control, LVI one-key impedance calculation High-frequency routine inspections for county-level power supply companies
Wuhan Hezhong Electric — Supports segmented sweep + linear sweep dual modes, compliant with DL/T 911-2016 Routine preventive testing/fault diagnosis
Local and Surrounding Manufacturers in Yangzhou
Considering your location in Yangzhou, the following enterprises are worth attention:
Yangzhou Sudian Electric Co., Ltd.: A professional manufacturer of power testing equipment local to Yangzhou. The transformer winding deformation tester is one of its core product lines, covering the frequency response method and low-voltage pulse method. Its products have been applied in State Grid, China Southern Power Grid, Kailuan Group, Tiangang, Shanghai Metro, etc., with sales and service networks in seven major regions nationwide.
Yangzhou Top Electric Technology Co., Ltd.: Provides the TP-ZWBB101 winding deformation tester, with a sweep range of 10Hz-2MHz, frequency accuracy of 0.001%, dynamic range of -120dB to +20dB, compliant with DL/T911-2016 and IEC60076-18 standards.
Yangzhou Bohao Electric Co., Ltd.: Focuses on supporting equipment for installation, repair, and testing. Its products have all functional modules required for Level 3 installation (repair, testing), including automatic wiring identification and enhanced anti-50Hz harmonic interference algorithms, and have been deployed in batches by 17 certified testing units in East China.
Nanjing Puyuan Electric Co., Ltd.: Located in Luhe, Nanjing, a national high-tech enterprise. Its transformer comprehensive testing system integrates a winding deformation analysis module and has been applied in major projects such as UHV substations and new energy power stations.
III. Key Points of On-Site Operation Specifications
Pre-Test Preparation
Remove external leads: All external connection leads on the bushing side of the transformer under test must be removed to eliminate external circuit interference.
Reliable grounding: The tester, transformer shell, and core should all be connected to a common grounding point using short and direct dedicated grounding wires.
Fix the tap changer: Each test must fix the on-load tap changer at the same position (usually at the highest tap position), otherwise the validity of longitudinal comparison will be compromised.
Data Analysis Criteria (According to DL/T 911-2016)
Deformation Degree Correlation Coefficient (Longitudinal Comparison) Correlation Coefficient (Lateral Comparison)
Normal >0.99 >0.98
Mild deformation 0.97–0.99 —
Moderate deformation 0.95–0.97 —
Severe deformation <0.95 —
IV. Procurement Decision Recommendations
Requirement Scenario Recommended Configuration Reference Direction
County-level power supply company/distribution network operation and maintenance Basic frequency response method, 1kHz-2MHz, portable type Local Yangzhou manufacturers (Sudian/Bohao), high cost-effectiveness, fast after-sales response
110kV-220kV substation preventive testing FRA + impedance dual method, -120dB dynamic range Wuhan Huayi/Sanxin/UHV
Provincial electric science research institute/large power generation group Wideband (20Hz-10MHz), high precision, rich template library Wuhan Zhongneng Xinyi ZNRZ-II
New energy station box-type substation inspection Portable type (≤7kg), IP54 protection, strong anti-interference Wuhan Huaneng Lianchuang HNLC-801
Transformer manufacturer factory quality inspection High degree of automation, one-key report generation
