Doble M5400 Sweep Frequency Response Analyzer (SFRA)
The Doble M5400 sweep frequency response analyzer for detecting hidden mechanical faults in transformers reactors, and other winding-based equipment. It sends an excitation signal into the winding and measures the returning signals across a wide frequency range. Comparing the response to a baseline or to results from similar units shows deviations that point to internal mechanical problems. Doble pioneered the sweep approach which it describes as the industry standard for frequency domain measurements. The M5400 uses a user supplied PC to run its software.
Key Features
- Wide frequency range: 10 Hz to 25 MHz with Doble recommending a default setting of 20 Hz to 2 MHz for most transformer work
- Fine resolution: frequency response measured at logarithmically spaced intervals of 1.2%
- High dynamic range and accuracy: auto scales each frequency measurement for an overall dynamic range of 80 dB with ±1 dB accuracy which Doble says is the best combination available
- Constant excitation level: a steady signal at each frequency for highly repeatable results
- Excitation source: one channel, 20 V peak to peak into 50 ohms short circuit protected with a 50 ohm source impedance
- Fast, high-quality sampling: a maximum sampling rate of 100 MS/s with 50 ohm input and output impedance
- Non-intrusive test technique: can be used any time a problem is suspected as well as for routine baseline tests
- Simple, robust test leads: meet IEC standards
- Windows-based SFRA software: compares and analyzes measurements and includes preconfigured templates to guide field test setup
- Field-ready design: built for high quality measurements in the field with a 3 year calibration interval according to Doble literature
- Expert support: backed by Doble client service engineers
Typical Applications
- Detecting core movement and winding deformation or displacement
- Finding faulty core grounds, partial winding collapse, and hoop buckling
- Identifying broken or loosened clamping structures
- Detecting shorted turns and open windings
- Baseline testing at the factory, and after transportation, crane delivery, or system faults
- Deciding whether a transformer can go back in service after a fault
Why Choose It
The Doble M5400 Sweep gives solid evidence of mechanical integrity so owners can catch damage early and avoid costly failures. Repeatable high dynamic range measurements make comparisons with baselines and sister units reliable.
