in the EPFR80 Frequency Response and Impedance Method ?

General Information:

The EPFR80 SFRA transformer sweep frequency response analyzer, also called transformer winding deformation analyzer, adopting the sweep frequency response analysis (SFRA) method that is being developed and perfected by developed countries in the world, the transformer winding deformation analyzer can accurately judge the internal faults of transformer based on the measurement of the characteristic parameters of transformer windings.
The coils and internal structure are determined after the transformer is designed and manufactured. If the coils of a multi-winding transformer have the same voltage level, but different winding methods, the corresponding parameters (Ci, Li) of each coil should be certain. Therefore, the frequency domain characteristic response of each coil will also be determined depending on the corresponding parameters, and the frequency spectrum between the corresponding three-phase coils is comparable.
The distribution parameters of the transformer winding will change if turn-to-turn short circuit and short circuit between phases occur during the test, or the relative displacement of coils is caused by the collision in the transport process, and the coils lose their shape due to electromagnetic tension in the states of short circuit and fault during operation. Further, the original frequency domain characteristics of the transformer will be affected and changed, that is, the frequency response will vary considerably and the resonance frequency point will shift. The transformer winding analyzer developed based on the response analysis method is such a novel non-destructive testing equipment for internal faults of transformer. It applies to the testing of internal structure faults of 63kV-500kV power transformers.

The EPFR80 SFRA analyzer will quantify the response changes of internal winding parameters in different frequency domains, and then determine the degree of change of internal windings according to the variables, the amplitude of frequency response change, the area and the trend of frequency response change. Thus, it can judge whether the transformer has been severely damaged and needs to be overhauled according to the measurement results.

The analyzer can judge the degree of fault of the transformer under operating conditions by comparing the difference in the characteristic spectrum between the faulty transformer coils whether the frequency domain characteristic spectrum was saved or not in the past. Of course, it will be easier to provide an accurate and powerful basis for the operation status, post-accident analysis and maintenance and repair of the transformer if there is a set of original winding characteristic spectrum.

The SFRA transformer sweep frequency response analyser, also called winding deformation analyzer is equipped with a high-precision measurement system composed of a laptop and a single-chip microcomputer. It is simple to operate with a compact structure and a perfect test analysis function. The operators who have read the instruction manual or have accepted short-term training can operate and use the analyzer themselves.

Main Technical Parameters of Frequency Response Method

Sweep mode
1.Distribution of linear sweep
Sweep measurement range: (10Hz)-(10MHz) 40000 sweep points; resolution of 0.25kHz, 0.5kHz and 1kHz.
2.Distribution of segmented sweep measurement
Sweep measurement range: (0.5kHz)-(1MHz) 2000 sweep points;

Amplitude measurement range

(-120dB) -(+20dB)

Amplitude measurement accuracy


Accuracy of sweep frequency


Signal input impedance


Signal output impedance


Signal output amplitude


In-phase test repetition rate


Dimension of measuring instrument

(Length, width and height): 370X300X170(mm)

Dimension of aluminum alloy cable box

(Length, width and height): 420X300X300(mm)

Total weight


Operating temperature

-10- +40

Storage temperature

-20- +70;

Relative humidity

<90%, noncondensing

More details on EPFR series SFRA transformer sweep frequency response analyser, transformer winding deformation analyzer, please contact Wuhan EP Hipot Electric