SFRA is a comparative method, meaning an evaluation of the transformer condition is done by comparing an actual set of SFRA results to reference results.

A valuable tool for transformer diagnostics is sweep frequency response analysis (SFRA), which consists of measuring the impedance of transformer windings over a wide range of frequencies. Faults, which change either the winding capacitances or the winding inductances, are detectable. Fault simulation programs have indicated that the following faults are detectable using SFRA:

l Additional turns on yoke or limbs

l Shorted turns

l Open windings

l Faulty core grounds

l Winding collapse

l Broken or loosened clamps

l Mechanical damage to windings

l Mechanical damage to core

l Loose turns

l “Normal” ageing

1.Introduction: 

l The structure and reference of the transformer is fixed after been made, Therefor, the frequency response of each winding will be almost the same normally.

l Some case such as cut off between circles or phases in experience, cut off or winding moved for the pull of power in running, winding moved for hit in transportation, could change the reference of the transformer ,of which the frequency response will be changed, we could detect the deformation according to the frequency response curve.

l Our company has designed the winding deformation tester base on the idea and the advanced technique.

l GDRZ-902 Transformer SFRA Sweep Frequency Response Analyzer could draw the frequency response curve accurately. Then we compare the curves horizontally or vertically to detect the deformation of the transformer.

l GDRZ-902 Transformer SFRA Sweep Frequency Response Analyzer is conformed to the standard of DL/T911 2004.

 

2.Technique characteristics

l Using the advanced technical of DDS;

l Using the high speed and advanced microprocessor to design;

l Using double channels of AD chip of 16 bits;

l With seven inch LCD touch screen of which the brightness can be adjusted;

l With thermal printer of which the print thick can be adjusted;

l It could store one hundred and twenty groups of data, which could be read to current screen or upload to the PC;

l With PC software using which we could upload data ,test, analyze data, print data, or create word document;

l Using USB2.0 to connect to the device;