Sweep Frequency Response (SFRA) | Detailed introduction of technical principles

The Sweep Frequency Response Analyzer (SFRA) is used for frequency response analysis of transformer windings. Its sweep frequency range is 10Hz-2MHz. This analyzer is also used to test the winding deformation of power transformers with voltage levels of 66kV and above, as well as other special-purpose transformers.

During operation or transportation, power transformers inevitably suffer from the impact of various fault short-circuit currents or physical impacts. Under the powerful electrodynamic force generated by the short-circuit current, the transformer windings may lose stability, leading to permanent deformation phenomena such as local twisting, bulging, or displacement. This will seriously affect the safe operation of the transformer.

The frequency response analysis method is used to measure transformer winding deformation according to the national power industry standard DL/T911-2016 and the international electrotechnical standard IEC60076-18. This method detects the amplitude-frequency response characteristics of each winding and compares the results longitudinally or laterally. Based on the degree of change in the amplitude-frequency response characteristics, the potential deformation of the transformer windings can be determined.

1. Employs a frequency sweep method to measure transformer winding characteristics. Without removing the transformer cover or disassembling it, it accurately measures the torsion, bulging, or displacement of windings in 66kV and above transformers by detecting the amplitude-frequency response characteristics of each winding.

2. Fast measurement speed: Measurement time for a single winding is 1-2 minutes.

3. Extremely high frequency accuracy: Frequency accuracy is 0.1%.

4. Employs digital frequency synthesis, resulting in higher frequency stability.

5. Uses 5000V voltage isolation and charge protection for computer safety during testing.

6. The instrument has an oscilloscope function for convenient real-time monitoring of test conditions.

7. Can simultaneously load 9 curves. Relevant parameters for each curve are automatically calculated, and the deformation of the windings is automatically diagnosed, providing diagnostic reference conclusions.

1. Measurement speed: 1-2 minutes for single-phase winding

2. Output voltage: Vpp-25V, automatically adjusted during testing

3. Output impedance: 50Ω

4. Input impedance: 1MΩ (50Ω matching resistor built into the response channel)

5. Sweep range: 10Hz-2MHz

6. Frequency accuracy: 0.1%

7. Sweep mode: Linear or logarithmic; sweep frequency and number of points can be arbitrarily set

8. Curve display: Amplitude-frequency curve

9. Wide dynamic range: -100dB-20dB

10. Power supply voltage: AC220V±10% (external power adapter); main unit power supply: DC12V

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