Signals - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.1.4.7
364
• The sag of overhead lines can reach an unacceptable value.
• If the temperature of conductors, for example aluminium conductors, becomes
too high, the material will be destroyed.
• In cables the insulation can be damaged as a consequence of overtemperature,
and therefore phase-to-phase or phase-to-earth faults can occur.
In stressed situations in the power system, the lines and cables may be required to be
overloaded for a limited time. This should be done without any risk for the above-
mentioned risks.
The thermal overload protection provides information that makes temporary
overloading of cables and lines possible. The thermal overload protection estimates
the conductor temperature continuously. This estimation is made by using a thermal
model of the line/cable that is based on the current measurement.
If the temperature of the protected object reaches a set warning level, a signal is given
to the operator. This enables actions in the power system to be done before dangerous
temperatures are reached. If the temperature continues to increase to the maximum
allowed temperature value, the protection initiates a trip of the protected line.

Signals

Table 399: T1PTTR Input signals
Name Type
I3P SIGNAL
BLK_OPR BOOLEAN
ENA_MULT BOOLEAN
AMB_TEMP FLOAT32
Table 400: T1PTTR Output signals
Name Type
OPERATE BOOLEAN
START BOOLEAN
ALARM BOOLEAN
BLK_CLOSE BOOLEAN
Default Description
- Three-phase currents
0=False Block signal for operate outputs
0=False Enable Current multiplier
0 The ambient temperature used in the calculation
Description
Operate
Start
Thermal Alarm
Thermal overload indicator. To inhibite reclose.
1MRS759142 C
REX640
Technical Manual