ABB REQ650 User Manual

6.5 Instantaneous residual overcurrent protection
EFPIOC
6.5.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Instantaneous residual overcurrent
protection
EFPIOC
IN>>
IEF V1 EN
50N
6.5.2 Application
In many applications, when fault current is limited to a defined value by the object
impedance, an instantaneous earth-fault protection can provide fast and selective
tripping.
The Instantaneous residual overcurrent EFPIOC, which can operate in 15 ms (50 Hz
nominal system frequency) for faults characterized by very high currents, is included
in the IED.
6.5.3 Setting guidelines
The parameters for the Instantaneous residual overcurrent protection EFPIOC are set
via the local HMI or PCM600.
Some guidelines for the choice of setting parameter for EFPIOC is given.
GlobalBaseSel: Selects the global base value group used by the function to define
(IBase), (UBase) and (SBase).
The setting of the function is limited to the operate residual current to the protection
(IN>>).
The basic requirement is to assure selectivity, that is EFPIOC shall not be allowed to
operate for faults at other objects than the protected object (line).
For a normal line in a meshed system single phase-to-earth faults and phase-to-phase-
to-earth faults shall be calculated as shown in figure
56 and figure 57. The residual
currents (3I
0
) to the protection are calculated. For a fault at the remote line end this
fault current is I
fB
. In this calculation the operational state with high source impedance
Z
A
and low source impedance Z
B
should be used. For the fault at the home busbar this
fault current is I
fA
. In this calculation the operational state with low source impedance
Z
A
and high source impedance Z
B
should be used.
1MRK 505 291-UEN A Section 6
Current protection
113
Application manual

ABB REQ650 Specifications

General

Brand	ABB
Model	REQ650
Category	Protection Device
Language	English