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Appendix 1: The relationship between the correlation coefficient and the degree of
transformer winding deformation
The transformer winding deformation tester of our company strictly follows the power
industry standard DL/T911-2016 "Frequency Response Analysis Method of Power
Transformer Winding Deformation" to analyze the degree of transformer winding
deformation. The relationship between the specific correlation coefficient and the degree
of transformer winding deformation is shown in the following table :
Table A.1 The relationship between correlation coefficient and transformer winding
deformation (for reference only)
Deformation degree of winding
Correlation coefficient R
Hard deformation
R
LF
＜
0.6
Obvious deformation
1.0
＞
R
LF
≥0.6 or R
MF
＜
0.6
Slight deformation
2.0
＞
R
LF
≥1.0 or 0.6 ≤ R
MF
＜
1.0
Normal winding
R
LF
≥ 2.0 and R
MF
≥1.0 andR
H F
≥0.6
Note: R
LF
is the correlation coefficient of the curve in the low frequency band
(1kHz
～
100kHz);
R
MF
is the correlation coefficient of the curve in the middle frequency band
(100kHz
～
600kHz);
R
HF
is the correlation coefficient of the curve in the high frequency range
(600kHz
～
1000kHz).
