Four Step Directional Negative Phase Sequence Overcurrent Protection Ns4Ptoc (46I2); Identification; Application - ABB Relion 670 Series Applications Manual

1MRK 511 358-UUS A
7.5 Four step directional negative phase sequence
overcurrent protection NS4PTOC (46I2)
7.5.1

Identification

Function description
Four step negative sequence
overcurrent protection
7.5.2

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.
In many applications several steps with different current pickup levels and time delays are needed.
NS4PTOC (4612) can have up to four, individual settable steps. The flexibility of each step of
NS4PTOC (4612) function is great. The following options are possible:
Non-directional/Directional function: In some applications the non-directional functionality is
used. This is mostly the case when no fault current can be fed from the protected object itself. In
order to achieve both selectivity and fast fault clearance, the directional function can be
necessary. This can be the case for unsymmetrical fault protection in meshed and effectively
grounded transmission systems. The directional negative sequence overcurrent protection is also
well suited to operate in teleprotection communication schemes, which enables fast clearance of
unsymmetrical faults on transmission lines. The directional function uses the voltage polarizing
quantity.
Choice of time characteristics: There are several types of time characteristics available such as
definite time delay and different types of inverse time characteristics. The selectivity between
different overcurrent protections is normally enabled by co-ordination between the operating
time of the different protections. To enable optimal co-ordination all overcurrent relays, to be co-
ordinated against each other, should have the same time characteristic. Therefore a wide range of
standardized inverse time characteristics are available: IEC and ANSI.
Application manual
IEC 61850 IEC 60617
identification identification
NS4PTOC
I2
4
alt
4
IEC10000053 V1 EN-US
Section 7
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
149