7 Operation
Maschinenfabrik Reinhausen GmbH 2019
188
5163667/06 EN
ETOS
®
IM
7.12.2 Hot-spot forecast (optional)
You can use the optional hot-spot forecast to calculate the hot-spot tempera-
ture based on load profile and ambient temperature for a 24 hour time pe-
riod. The calculation can either be made in accordance with IEC 60076-7 or
IEEE Std C57.91 (Clause 7 model). The diagram also shows you the load
factor and the relative aging rate of the transformer.
Figure 139: Hot-spot forecast
For the hot-spot forecast calculation, you must enter the desired values for
load factor and ambient temperature for every hour. The device uses the
currently measured values as the starting values. The remaining values are
prepopulated with the measured values from the previous day. If no mea-
sured values are available, the device uses the factory setting.
If you call up the visualization using a PC, you can export the calculated val-
ues as a csv file.
To be able to use the hot-spot forecast, you must first set the parameters for
the following functions:
– Calculation method
– Hot-spot factor (only with IEC 60076-7 calculation method)
– Gradient (only with IEC 60076-7 calculation method)
– Winding exponent (only with IEC 60076-7 calculation method)
– Oil time constant (only with IEC 60076-7 calculation method)
– k21 (only with IEC 60076-7 calculation method)
– k22 (only with IEC 60076-7 calculation method)
– Gradient (only with IEEE Std C57.91 calculation method)
– Exponent (only with IEEE Std C57.91 calculation method)
– Winding time constant (with IEC 60076-7 and IEEE Std C57.91 calcula-
tion methods)
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