PFRS-25 Transformer Frequency Response Analyzer

The PFRS-25 is a power transformer frequency sweep response analyzer designed to confirm the mechanical integrity of a power transformer by measuring the frequency response per the IEEE C57.149-2012 and IEC 60076-18 standards. The included test and analysis software can be used to perform tests automatically and to graphically compare test results and provide correlation analysis per the IEEE C57.149-2012 and DL/T 911-2004 standards. The software can be used to quickly assess the mechanical and electrical integrity of the transformer under test.

The PFRS-25 can confirm the mechanical integrity of a transformer by comparing the frequency response of the transformer with the previous known results. Every transformer has a unique frequency response system which changes if the mechanical geometry of the transformer is changed. These changes can occur due to physical movement or transportation. The physical geometry can also change if the transformer experiences high fault current due to internal or external fault. The fingerprint comparison of the frequency response system can be used to detect power transformer problems such as:

  • Core movements
  • Shorted turns or open windings 
  • Winding displacements or deformations
  • Winding connection problems
  • Broken clamping structures



Ambient Temperature
Operating -20°C to +55°C (-4°F to +131°F)
Storage -20°C to 70°C (-4°F to +158°F)
Humidity < 95% RH, non-condensing


EMC 2004/108/EC
LVD 2006/95/EC


AC power supply 90 – 264 V AC, 47 – 63 Hz
Internal battery 3.2 Ah, 38 Watts
Dimensions 13'' x 11'' x 6'' (34 cm x 29 cm x 15 cm)
Weight 10.0 lbs. (4.5 Kg) Includes the field rugged ABS Enclosure
Transportation Case (optional) 24.5” x 19.37” x 12.22” / 62.33 cm x 49.2 cm x 31.04 cm


Frequency Range 0.1 Hz – 25 MHz, user selectable
Frequency Resolution 0.01% OR 0.001Hz
Frequency Accuracy 0.01% (measurement error)
Level Resolution 0.0005 dB
Number of Points Default 1046, Up to 32,000 points (user selectable)
Measurement Time <20 S, fast setting 6 s (20 Hz – 2 MHz)
Points Spacing Log, linear, or both
Sweep Settings 20 Hz to 2 MHz
Internal Noise Level (average) >140 dB
Dynamic Range >150 dB
Accuracy ±0.1 dB from +10 to -40 dB and ±0.3 dB (min) below -40 dB
IF Bandwidth User selectable; default <10%
PC Communication USB and Bluetooth
Software Windows-compatible
Standards/Guides Fulfills requirements in IEC 60076-18, IEEE C57.149-2012, CIGRE Technical Brochure 342, DL/T 911-2004, as well as other international standards and recommendations


Channels 1
Compliance Voltage 0.2 – 24 V p-p
Measurement voltage at 50 Ω 0.1 – 12 V P-P
Channel Protection Short-circuit and over-voltage protection
Sweep Direction Low to high or high to low
Frequency Range 0.1 Hz – 25 MHz, user selectable


Channels 2
Sampling Simultaneous
Frequency Range 0.1 Hz – 25 MHz
Input Impedance 50 Ω
Sampling Rate 100 MS/s

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