Insulation Resistance – Temperature Correction Factors (to 20 °C)

Resistances

Insulation Resistance – Temperature Correction Factors (to 20 °C)

The following table provides temperature correction factors used to convert measured insulation resistance values of oil-immersed transformers to the reference temperature of 20 °C. The correction factor depends on the winding temperature at the time of measurement.

Temperature Correction Factors for Oil-Immersed Transformers
(To convert insulation resistance to 20 °C)
Temperature
(°C)		 Temperature
(°F)		 Correction Factor
(to 20 °C)
0 32 0.25
5 41 0.36
10 50 0.50
15 60 0.74
20 68 1.00
25 77 1.40
30 86 1.98
35 95 2.80
40 104 3.95
45 113 5.60
50 122 7.85
55 131 11.20
60 140 15.85
65 149 22.40
70 158 31.75
75 167 44.70
Note: The measured insulation resistance value must be multiplied by the correction factor corresponding to the winding temperature to obtain the equivalent value at 20 °C.
Example: A measured value of 1200 MΩ at 35 °C becomes:
1200 × 2.80 = 3360 MΩ (corrected to 20 °C)

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DATSAN Transformer manufactures oil-immersed distribution and power transformers for industrial, utility, and infrastructure projects worldwide.

Established in 1992, DATSAN combines over 30 years of engineering experience with modern manufacturing and testing capabilities. Our products are designed in accordance with IEC 60076, ANSI C57 and relevant international standards, with Ecodesign-compliant options available upon request.

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Datsan Elk. İnş. San. ve Tic. Ltd. Şti.

Address: Kızıltepe Mardin Karayolu 6.km
Kızıltepe, 47400 Mardin / TÜRKİYE

Phone : +90 (482) 215 3188
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