97
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Consumed Life
The 509ITM
calculates relative “life consumption” according to IEEE standards. These
standards are based on the Arrhenius formulas for deterioration of organic insulation
material with time and temperature. Each 6 - 8 degree increase in temperature
approximately doubles the rate of life decay. Based on the cumulative exponential affects of
temperature over time, the life consumption metering helps to prioritize maintenance
activities between transformers. It also helps to equalize the load between transformers to
maximize system life and minimize maintenance.
includes the fields described below.
Life
Consumption
Formula
Variables
Depending on the application, allows you to select different Unity Hot
Spot Temperatures by entering the corresponding constants. Unity Hot
Spot Temperature is defined as the value of the winding temperature at
which exactly one hour of consumed life has occurred.
The 509ITM uses the IEEE Std C57.91-1995 and CEI/IEC 354:1991 for
calculating the transformer loss of life in its life-consumption equations.
Both standards use Montsinger
’s rule of thermal degradation, which is a
simplified version of Arrhenius
’ Law of General Chemical/Thermal
Degradation.
See the following table for recommended values.
A
B
Unity Hot Spot
Notes
Temperature (° C)
-11.269 6328.8
110
Recommended for 65° C insulation
-11.968 6328.8
95
Recommended for 55° C insulation
-11.804 6328.8
98
IEC 354:1991 specification
-13.391 6972.15
101
Summary of Contents for 509ITM Series
Page 26: ...26 www qualitrolcorp com Current Input Wiring...
Page 55: ...55 www qualitrolcorp com 3 Continue with the setup procedure...
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Page 144: ...144 www qualitrolcorp com The following window will appear...
Page 167: ...167 www qualitrolcorp com The Customer Setup window displays 4 Click Load Tap Changer...
Page 178: ...178 www qualitrolcorp com Appendix...
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