Four Step Residual Overcurrent Protection, Zero, Negative Sequence Direction Ef4Ptoc (51N/67N) - ABB REC650 ANSI Technical Manual

Section 6
Current protection
6.4
6.4.1
6.4.2
98
Four step residual overcurrent protection, zero,
negative sequence direction EF4PTOC (51N/67N)
Identification
Function description
Four step residual overcurrent
protection, zero or negative sequence
direction
Functionality
The four step residual overcurrent protection, zero or negative sequence direction
(EF4PTOC, 51N/67N) has independent inverse time delay settings for step 1 and 4. Step
2 and 3 are always definite time delayed.
All IEC and ANSI inverse time characteristics are available.
EF4PTOC (51N/67N) can be set directional or non-directional independently for each of
the steps.
The directional part of the function can be set to operate on following combinations:
• Directional current (I3PDir) versus Polarizing voltage (V3PPol)
• Directional current (I3PDir) versus Polarizing current (I3PPol)
• Directional current (I3PDir) versus Dual polarizing (VPol+ZPol x IPol) where ZPol
= RPol + jXPol
IDir, VPol and IPol can be independently selected to be either zero sequence or negative
sequence.
Other setting combinations are possible, but not recommended.
Second harmonic blocking level can be set for the function and can be used to block each
step individually.
EF4PTOC (51N/67N) can be used as main protection for phase-to-ground faults.
IEC 61850 IEC 60617
identification identification
EF4PTOC
2
IEC11000263 V1 EN
1MRK 511 287-UUS A
ANSI/IEEE C37.2
device number
51N/67N
Technical manual