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Sweep frequency response analysis (SFRA) is a method to evaluate the mechanical integrity of core, windings, and clamping structures within power transformers by measuring their electrical transfer functions over a wide frequency range.
FRA500 injects a sine wave signal with constant amplitude and variable frequency (user-selectable voltage from 0,2 Vpp to 24 Vpp and frequency from 0,1 Hz to 32 MHz) to one side of a transformer winding. These amplitudes and phase angle values of the reference (output) signal are then compared with the corresponding values of the measured signal (from the second side of the winding). The ratio of the measured signal and reference signal magnitude is graphically displayed in dB through the full sweep frequency.
The response voltage measurement is made across an impedance of 50 Ω. Any coaxial lead connected between the test object terminal and the voltage measuring instrument shall have a matched impedance. To make an accurate ratio measurement, the technical parameters of the reference and response channels of the measuring instrument and any measurement leads shall be identical.
Mechanical or electrical changes in a transformer are detected by comparing their frequency response measurement fingerprints. This comparison can be used to detect power transformer problems such as:
A typical test sweep time, with frequency ranging from 20 Hz to 2 MHz, using FRA500 is less than 20 seconds. In addition, there is a “Quick Sweep” feature that allows the user to verify the cable connection integrity and earthing in 10 seconds.
Each FRA500 is delivered with Windows-based Sweep Frequency Analysis (DV FRA) software that can be used to conduct tests and capture data. The software can graphically compare test results as a magnitude vs. frequency graph, in-phase vs. frequency graph, or display both graphs at the same time. The software also provides an analytical tool that can perform correlation coefficients between two traces per the IEEE C57.149 – 2012 or DL/T 911-2004 standard.
DV FRA Software can directly import and playback Doble, Megger, and Omicron SFRA test records allowing the user to compare the FRA500 test records against other devices on the market.
To eliminate the use of long cables FRA500 can be battery-operated (optional) and has a Bluetooth communication feature.
The FRA500 is designed for Sweep Frequency Response Analysis (SFRA) testing of power transformers. It evaluates the mechanical and electrical integrity of transformer windings, core, and clamping structures by measuring their frequency response over a wide frequency range.
Sweep Frequency Response Analysis (SFRA) is a diagnostic method used to detect mechanical and electrical changes inside power transformers. It works by comparing the transformer’s frequency response fingerprint with previous measurements or reference results.
SFRA testing helps identify hidden transformer defects that may not be detected by routine electrical tests. It is one of the most sensitive methods for detecting winding movement, deformation, core displacement, and mechanical damage.
The FRA500 can help detect winding deformation, winding displacement, shorted turns, open windings, core movement, broken clamping structures, winding connection problems, and other mechanical changes within the transformer.
SFRA testing is commonly performed during transformer commissioning, after transportation, after short-circuit events, after repairs, during condition assessments, and as part of preventive maintenance programs.
The FRA500 injects a sinusoidal signal with variable frequency into a transformer winding and compares the reference signal with the measured response. The resulting frequency response curve is used to assess transformer condition.
The FRA500 provides a user-selectable frequency range from 0.1 Hz up to 32 MHz, allowing detailed analysis of transformer mechanical and electrical characteristics.
The FRA500 can complete a typical sweep from 20 Hz to 2 MHz in less than 20 seconds, significantly reducing transformer testing time compared to many conventional SFRA instruments.
Quick Sweep is a fast verification test that checks cable connections and grounding integrity before a full SFRA measurement. This feature helps users confirm proper test setup in only a few seconds.
Yes. One of the most common applications of SFRA testing is verifying transformer mechanical integrity after transportation or relocation to ensure no internal movement occurred during transit.
Yes. The FRA500 software allows comparison of measured traces with historical fingerprints, sister units, or reference measurements, helping engineers identify changes in transformer condition.
Yes. The FRA500 is designed in accordance with recognized SFRA standards and guidelines, including DL/T 911, IEC 60076-18 and IEEE C57.149.
DV-FRA software provides automated trace comparison, advanced short-circuit analysis, support for IEEE and DL/T comparison methods, report generation, and the ability to import SFRA files from other manufacturers.
Winding resistance testing evaluates the electrical resistance of transformer windings and connections, while SFRA testing evaluates the mechanical condition of transformer windings, core, and internal structures. Both tests provide complementary diagnostic information.
The FRA500 combines a wide frequency range, extremely fast measurement speed, advanced analysis software, Quick Sweep verification, and compliance with international standards, making it a powerful solution for transformer mechanical integrity assessment.
