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Basic description of the Transformer Monitor
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The following equation can be derived in common logarithms from equation (1) with Θ
hN
=
98°C.
(2)
This relationship is shown in the below table:
Θ
h
in °C
Relative service life consumption
80
0.125
86
0.25
92
0.5
98
1.0
104
2.0
110
4.0
116
8.0
122
16.0
128
32.0
134
64.0
140
128.0
Example:
10 hours at 104°C and 14 hours at 86°C consume (10 h x 2) + (14 h x 0.25) = 23.5 hours dur-
ing an operation period of 24 hours.
Note that the service life consumption is negligible below 80°C.
When the load and ambient temperature are constant, the relative service life consumption
is calculated with the relationship V x t. 't' is the time under load and V is the relative ser-
vice life consumption from equation (1).
More commonly, when the operating conditions are not constant, the transformer's service
life consumption is calculated according to the following equation:
∫
or
∑
n : Number of a time interval
N : Total number of the same time intervals
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