ABB Relion REQ650, Applications Manual

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6.2 Instantaneous phase overcurrent protection phase
segregated output SPTPIOC
6.2.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Instantaneous phase overcurrent
protection, phase segregated output
SPTPIOC
3I>>
SYMBOL-Z V1 EN
50
6.2.2 Application
Long transmission lines often transfer great quantities of electric power from
production to consumption areas. The unbalance of the produced and consumed
electric power at each end of the transmission line is very large. This means that a fault
on the line can easily endanger the stability of a complete system. The transient
stability of a power system depends mostly on three parameters (at constant amount
of transmitted electric power):
• The type of the fault. Three-phase faults are the most dangerous, because no
power can be transmitted through the fault point during fault conditions.
• The magnitude of the fault current. A high fault current indicates that the decrease
of transmitted power is high.
• The total fault clearing time. The phase angles between the Electro motive forces
(EMFs) of the generators on both sides of the transmission line increase over the
permitted stability limits if the total fault clearing time, which consists of the
protection operating time and the breaker opening time, is too long.
The fault current on long transmission lines depends mostly on the fault position and
decreases with the distance from the generation point. For this reason the protection
must operate very quickly for faults very close to the generation (and relay) point, for
which very high fault currents are characteristic.
The instantaneous phase overcurrent protection phase segregated output SPTPIOC
can operate in 10 ms for faults characterized by very high currents.
6.2.3 Setting guidelines
The parameters for Instantaneous phase overcurrent protection phase segregated
output SPTPIOC are set via the local HMI or Protection and Control Manager
(PCM600). This protection function must operate only in a selective way. So check all
system and transient conditions that could cause its unwanted operation.
Section 6
1MRK 505 291-UEN A
Current protection
90
Application manual