Winding Deformation Tester
The transformer winding deformation tester (also known as the Frequency Response Analysis (FRA) tester) is the core equipment 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 being subjected to short-circuit impacts or transportation collisions, enabling rapid judgment without the need to lift the tank.
The following is a practical procurement guide based on the latest 2026 industry standards:
I. Core Selection Parameters: 6 Hard Indicators That Must Be Verified
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 (the low-frequency band reflects overall deformation, the mid-frequency band reflects local bulging, and the high-frequency band 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～+20dB, with high-end models reaching -120dB～+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, the curve coincidence degree 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
Priority should be given to comprehensive testers that support both the Frequency Response Analysis (FRA) method + Low Voltage Short-Circuit 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 power research institutes at or above the provincial level.
II. Recommended Mainstream Brands and Models
High-Quality Domestic Brands (mainly from the Wuhan/Jiangsu industrial belts)
Brand Representative Model Core Advantages Applicable Scenarios
RBX Series Dual-method fusion (FRA + impedance), 20Hz-10MHz wide frequency, -120dB dynamic range, IP54 protection Preventive testing for State Grid substations
Complete product line, cooperation with Huazhong University of Science and Technology, providing one-stop comprehensive transformer testing solutions Factory acceptance testing for transformer manufacturers
ZNRZ-II Dual-channel synchronous sampling, built-in 128 sets of FRA template libraries, verified for 3+ years at 32 220kV stations Provincial electric power 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 inspection for county-level power supply companies
Supports dual modes of segmented frequency sweep + linear frequency sweep, 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:
The transformer winding deformation tester is one of the core product lines, covering the frequency response method and the low-voltage pulse method. The 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.
Provides the TP-ZWBB101 winding deformation tester, with a frequency sweep range of 10Hz-2MHz, frequency accuracy of 0.001%, dynamic range of -120dB～+20dB, compliant with DL/T911-2016 and IEC60076-18 standards.
Focuses on supporting equipment for installation, repair, and testing. The 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.
Located in Luhe, Nanjing, a national-level high-tech enterprise. Its comprehensive transformer testing system integrates a winding deformation analysis module and has been applied in major projects such as ultra-high-voltage 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.
Fixing 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 (based on 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/Baihao), high cost-performance, fast after-sales response
110kV-220kV substation preventive testing FRA + impedance dual method, -120dB dynamic range Wuhan Huayi/Sanxin/Ultra-high-voltage
Provincial electric power research institute/large power generation group Wide frequency (20Hz-10MHz), high precision, rich template library Wuhan Zhongneng Xinyi ZNRZ-II
New energy station box transformer 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
