ABB RELION REX640 Technical Manual page 1394

Condition monitoring functions
Figure 792: Variation of insulation ageing factor with hot-spot temperature (Graph
produced using values from Table 11 of IEEE Std. C57.91-1995)
The variation of insulation life with respect to the hot-spot temperature depends
upon the type of insulation paper used. Thermally upgraded insulation paper
neutralizes the production of acids caused by the hydrolysis of the material over
the lifetime of the transformer and slows down insulation ageing when compared to
the normal insulation paper (IEC 60076-7). The proper selection of insulation paper
type is needed for better accuracy of loss of life calculation.
In certain cases, it is necessary to monitor the loading of the transformer over a
defined time period. For example, during a planned overloading of a transformer for
a period of one month. In such cases it is important to know the ageing rate during
that period of overload rather than the overall loss of life transformer. Hence, an
additional output on average ageing rate over a settable average ageing period is
provided in the function.
The function can be applied for new transformers and also for transformers already
in service using the
7.3.7 Signals
7.3.7.1 HSARSPTR Input signals
Table 1325: HSARSPTR Input signals
Name
I3P
TOIL_TEMP
AMB_TEMP
Table continues on the next page
1394
Initial loss of life setting.
Type
SIGNAL
FLOAT32
FLOAT32
Default Description
- Three-phase currents
0 Measured top oil tem-
perature
0 Measured ambient
temperature
1MRS759142 F
REX640
Technical Manual