ABB RELION 620 Series Technical Manual page 389

1MAC504801-IB E
620 series ANSI
Technical Manual
the share of the steep part of the heating curve. When Weighting factor p =1, only Short-
time constant is used. When Weighting factor p = 0, only Long time constant is used.
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Figure 176: Effect of the Weighting factor p factor and the difference between the two
time constants and one time constant models
The actual temperature of the transformer is calculated by adding the ambient temperature
to the calculated temperature.
Θ = ∆ + Θ Θ
amb
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Θ temperature in transformer (°C)
ΔΘ calculated temperature rise (°C) in transformer
Env temperature Set setting or measured ambient temperature
Θ set value of the
amb
The ambient temperature can be measured with RTD measurement. The measured
temperature value is connected, for example, from the RTD/mA output of the X130
(RTD) function to the AMB_TEMP input of 49T.
The Env temperature Set setting is used to define the ambient temperature if the ambient
temperature measurement value is not connected to the AMB_TEMP input. The Env
Section 4
Protection functions
(Equation 26)
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