Wattmetric-Based Earth-Fault Protection Wpwde - ABB RELION 620 Series Technical Manual

Protection functions
4.2.7

Wattmetric-based earth-fault protection WPWDE

4.2.7.1 Identification
Function description
Wattmetric-based earth-fault pro-
tection
4.2.7.2 Function block
Figure 238: Function block
4.2.7.3 Functionality
The wattmetric-based earth-fault protection function WPWDE can be used to
detect earth faults in unearthed networks, compensated networks (Petersen coil-
earthed networks) or networks with a high-impedance earthing. It can be used
as an alternative solution to the traditional residual current-based earth-fault
protection functions, for example, the IoCos mode in the directional earth-fault
protection function DEFxPDEF.
WPWDE measures the earth-fault power 3UoIoCosφ and gives an operating signal
when the residual current Io, residual voltage Uo and the earth-fault power exceed
the set limits and the angle (φ) between the residual current and the residual
voltage is inside the set operating sector, that is, forward or backward sector. The
operating time characteristic can be selected to be either definite time (DT) or a
special wattmetric-type inverse definite minimum type (wattmetric type IDMT).
The wattmetric-based earth-fault protection is very sensitive to current transformer
errors and it is recommended that a core balance CT is used for measuring the
residual current.
The function contains a blocking functionality. It is possible to block function
outputs, timers or the function itself, if desired.
4.2.7.4 Operation principle
The function can be enabled and disabled with the
corresponding parameter values are "On" and "Off".
468
For WPWDE, certain notations and definitions are used.
Residual voltage Uo = (UA+UB+UC)/3 = U
voltage
Residual current Io = -(IA+IB+IC) = 3×- I
current
IEC 61850 IEC 60617
identification identification
WPWDE Po> ->
Operation setting. The
, where U
0
, where I
0
1MRS757644 H
ANSI/IEEE C37.2
device number
32N
= zero-sequence
0
= zero-sequence
0
620 series
Technical Manual