For troubleshooting, check the contents of this chapter and also the preprocessing
blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
7.3.5
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "on" and "off".
The operation of HSARSPTR can be described with a module diagram. All modules in
the diagram are explained in the next sections.
Load factor
calculation
and
parameter
selection
Hotspot
temp
calculation
TOIL_TEMP
ALARM
WARNING
BLOCK
AMB_TEMP
Top oil
temp
calculation
Level
detector 1
Ageing
and
loss of life
calculation
RESET
I3P
I_A
I_B
I_C
Level
detector 2
ALM_AGE_RATE
RST_AVGAGING
TOPOIL_TEMP
HOTSPOT_TEMP
Figure 789: Functional module diagram
7.3.5.1
Load factor calculation and parameter selection
The transformer top oil and hot-spot temperatures are dependent on the load
factor, the winding conductor properties and the cooling oil properties of the
transformer. This module calculates the load factor based on the measured phase
currents and selects the transformer parameters based on user defined settings.
Load factor calculation
Load factor is a ratio of the load current to the rated current. Since the thermal
content of all the three phase currents influence the temperature inside the
transformer, the load factor is calculated as a ratio of the root of sum of squared
phase currents to three times the rated current.
K
I
A
I
B
I
C
I
rated
=
+
+
⋅
_
_
_
2
2
2
2
3
(Equation 321)
Where
Condition monitoring functions
1MRS759142 F
1384
REX640
Technical Manual