Four Step Directional Negative Phase Sequence Overcurrent Protection Ns4Ptoc (46I2) - ABB RELION RET670 Applications Manual

1MRK 504 163-UUS A
9.5
9.5.1
9.5.2
Transformer protection RET670 2.2 ANSI
Application manual
can be chosen very low. As it is required to detect ground faults in the transformer
winding, close to the neutral point, values down to the minimum setting possibilities
can be chosen. However, one must consider zero-sequence currents that can occur
during normal operation of the power system. Such currents can be due to un-
transposed lines.
In case to protection of transformer windings not feeding residual current at external
ground faults, a fast low current step can be acceptable.
Four step directional negative phase sequence
overcurrent protection NS4PTOC (46I2)
Identification
Function description
Four step negative sequence
overcurrent protection
Application
Four step negative sequence overcurrent protection NS4PTOC (4612) is used in
several applications in the power system. Some applications are:
• Ground-fault and phase-phase short circuit protection of feeders in effectively
grounded distribution and subtransmission systems. Normally these feeders have
radial structure.
• Back-up ground-fault and phase-phase short circuit protection of transmission
lines.
• Sensitive ground-fault protection of transmission lines. NS4PTOC (4612) can
have better sensitivity to detect resistive phase-to-ground-faults compared to
distance protection.
• Back-up ground-fault and phase-phase short circuit protection of power
transformers.
• Ground-fault and phase-phase short circuit protection of different kinds of
equipment connected to the power system such as shunt capacitor banks, shunt
reactors and others.
IEC 61850 IEC 60617
identification identification
NS4PTOC
I2
4
alt
4
IEC10000053 V1 EN-US
Section 9
Current protection
GUID-E8CF8AA2-AF54-4FD1-A379-3E55DCA2FA3A v1
GUID-E1720ADA-7F80-4F2C-82A1-EF2C9EF6A4B4 v1
ANSI/IEEE C37.2
device number
46I2
GUID-343023F8-AFE3-41C2-8440-1779DD7F5621 v2
549