ABB Relion 670 Series Applications Manual page 135

1MRK 511 401-UUS F
Section 8
8.1 Instantaneous phase overcurrent protection PHPIOC (50)
8.1.1 Identification
Function description
Instantaneous phase overcurrent
protection
8.1.2 Application
Long transmission lines often transfer great quantities of electric power from generation 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 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 PHPIOC (50) can operate in 10 ms for faults
characterized by very high currents.
8.1.3 Setting guidelines
The parameters for instantaneous phase overcurrent protection PHPIOC (50) are set via the local
HMI or PCM600.
Bay control REC670
Application manual
Current protection
IEC 61850
identification
PHPIOC
© Copyright 2017 ABB. All rights reserved
IEC 60617 ANSI/IEEE C37.2
identification device number
50
3I>>
SYMBOL-Z V1 EN-US
Section 8
Current protection
IP14506-1 v6
M14880-1 v5
M12911-3 v6
IP14979-1 v1
M12915-4 v9
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