tVN
is the definite time delay for the trip function of the residual voltage protection,
given in s.
8.7
Thermal overload protection, one time constant
Fahrenheit/Celsius LFPTTR/LCPTTR (26)
IP14512-1 v7
8.7.1
Identification
8.8
Thermal overload protection, two time constants
TRPTTR (49)
IP14513-1 v4
8.8.1
Identification
M14877-1 v2
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Thermal overload protection, two time
constants
TRPTTR
SYMBOL-A V1 EN-US
49
8.8.2
Application
M15341-3 v5
Transformers in the power system are designed for a certain maximum load current
(power) level. If the current exceeds this level the losses will be higher than expected.
As a consequence the temperature of the transformer will increase. If the temperature
of the transformer reaches too high a value, the equipment might be damaged;
•
The insulation within the transformer experiences forced ageing. As a
consequence of this, the risk of internal phase-to-phase or phase-to-ground faults
increases.
•
There might be hot spots within the transformer, which degrades the paper
insulation. It might also cause bubbling in the transformer oil.
In stressed situations in the power system it can be required to overload transformers
for a limited time. This should be done without the above mentioned risks. The thermal
Section 8
1MRK 511 401-UUS A
Current protection
202
Bay control REC670 2.2 ANSI
Application manual
Summary of Contents for Relion REC670
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