ABB Relion REC670 - Four Step Residual Overcurrent Protection, (Zero Sequence or Negative Sequence Directionality) EF4 PTOC; Identification; Application

I m in M A X I
fA
I
fB
I
M
, ,( )³
EQUATION287 V1 EN-US (Equation 36)
Where:
I
fA
and I
fB
have been described for the single line case.
Considering the safety margins mentioned previously, the minimum setting (Is) is:
I
s
= 1.3 × I
min
EQUATION288 V3 EN-US (Equation 37)
Transformer inrush current shall be considered.
The setting of the protection is set as a percentage of the base current (
IBase ).
Operation : set the protection to On or Off .
IN>> : Set operate current in % of IBase .
StValMult : The operate current can be changed by activation of the binary input ENMULT to
the set factor
StValMult .
7.4 Four step residual overcurrent protection, (Zero
sequence or negative sequence directionality)
EF4PTOC
IP14509-1 v6
7.4.1 Identification
M14881-1 v5
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Four step residual overcurrent
protection
EF4PTOC
4(IN>)
4
alt
4
TEF-REVA V2 EN-US
51N_67N
7.4.2 Application
M12509-12 v9
The four step residual overcurrent protection EF4PTOC is used in several applications in the
power system. Some applications are:
• Earth-fault protection of feeders in effectively earthed distribution and subtransmission
systems. Normally these feeders have radial structure.
• Back-up earth-fault protection of transmission lines.
• Sensitive earth-fault protection of transmission lines. EF4PTOC can have better sensitivity
to detect resistive phase-to-earth-faults compared to distance protection.
• Back-up earth-fault protection of power transformers.
• Earth-fault protection of different kinds of equipment connected to the power system
such as shunt capacitor banks, shunt reactors and others.
1MRK 511 358-UEN A Section 7
Current protection
117
Application manual