Table 105:
TRPTTR (49) Non group settings (basic)
Name
Values (Range)
Unit
Step
Default
Description
GlobalBaseSel
1 - 6
-
1
1
Selection of one of the Global Base Value
groups
8.4.6
Monitored data
Table 106:
TRPTTR (49) Monitored data
Name
Type
Values (Range)
Unit
Description
TTRIP
REAL
-
-
Estimated time to trip (in min)
TTRIPCAL
INTEGER
-
-
Calculated time status to trip:
not active/long time/active
TRESCAL
INTEGER
-
-
Calculated time status to
reset: not active/long time/
active
TRESLO
REAL
-
-
Estimated time to reset of the
function (in min)
HEATCONT
REAL
-
%
Percentage of the heat
content of the transformer
I-MEASUR
REAL
-
%
Current measured by the
function in % of the rated
current
8.4.7
Operation principle
The sampled analog phase currents are pre-processed and for each phase current the true
RMS value of each phase current is derived. These phase current values are fed to the
Thermal overload protection, two time constants (TRPTTR, 49).
From the largest of the three phase currents a relative final temperature (heat content) is
calculated according to the expression:
2
final
ref
I
I
æ
ö
Q
= ç
÷
ç
÷
è
ø
EQUATION1171 V1 EN
(Equation 56)
where:
I
is the largest phase current
I
ref
is a given reference current
1MRK 502 048-UUS A
Section 8
Current protection
237
Technical manual
