The thermal overload protection estimates the internal heat content of the transformer/
generator (temperature) continuously. This estimation is made by using a thermal model
of the transformer/generator with two time constants, which is based on current
measurement.
Two warning pickup levels are available. This enables actions in the power system to be
done before dangerous temperatures are reached. If the temperature continues to increase
to the trip value, the protection initiates a trip of the protected transformer/generator.
Estimated time to trip before operation is presented.
8.4.3
Function block
ANSI08000037-1-en.vsd
TRPTTR (49)
I3P*
BLOCK
COOLING
RESET
TRIP
PICKUP
ALARM1
ALARM2
LOCKOUT
WARNING
ANSI08000037 V1 EN
Figure 106:
TRPTTR (49) function block
8.4.4
Signals
TRPTTR is not provided with external temperature sensor in first release
of 650 series. The only input that influences the temperature measurement
is the binary input COOLING.
Table 102:
TRPTTR (49) Input signals
Name
Type
Default
Description
I3P
GROUP
SIGNAL
-
Three phase group signal for current input
BLOCK
BOOLEAN
0
Block of function
COOLING
BOOLEAN
0
Cooling input changes IBase setting and time constant
RESET
BOOLEAN
0
Reset of function
1MRK 502 048-UUS A
Section 8
Current protection
235
Technical manual
