Sweep frequency response analyzer

Data records

• The test is comparative: the measured trace is judged against a reference fingerprint of the same transformer, and the position along the frequency range at which the traces deviate indicates which kind of mechanical change has occurred. Source: OMICRON product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.baseline-comparison
• Deviations in the frequency response reveal winding deformation and displacement, hoop buckling, shorted or open windings, loose or broken clamping structures, core movement and core connection problems. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.detects
• The analyzer is verified in the field by sweeping a standard test object supplied with it, together with short-circuit and open-circuit self-tests of the leads, because there is otherwise no intuitive way to tell that a field trace is correct. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.instrument-verification
• Reproducibility depends on the connection technique: clamps with firm contact on the bushing terminals, the shortest possible braided ground from each clamp to the bushing flange, and a ground loop check before each sweep, because poor grounding shows up as a changed response at the highest frequencies. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.leads-and-grounding
• A sweep frequency response analyzer injects a low-voltage signal into one end of a transformer winding and measures the output at the other end across a wide range of frequencies, giving the electrical transfer function of the winding as a magnitude and phase trace. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.method
• For a valid comparison the tap changer positions, bushings and oil level must match the reference measurement, the transformer must be isolated from the bus, and the sweep is made before any DC winding resistance test or after demagnetization, because a magnetized core shifts the low-frequency response. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.test-conditions
• Four configurations are used: open-circuit self admittance, short-circuit self admittance with the other winding shorted, capacitive inter-winding and inductive inter-winding, which together separate the influence of the core from that of the windings. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.test-configurations
• The test is run after short-circuit or through-fault events, before and after transportation, after seismic activity, and when gas analysis or a protective trip suggests mechanical damage. Source: OMICRON product page, web page edition. Verified 2026-10-27. Record instr.sweep-frequency-response-analyzer.when-tested