Wattmetric-Based Earth-Fault Protection Wpwde - ABB RELION REC615 Technical Manual

Protection functions
Characteristic
Reset ratio
Operate time accuracy in definite time mode
Operate time accuracy in IDMT mode .
Suppression of harmonics
4.2.6

Wattmetric-based earth-fault protection WPWDE

4.2.6.1 Identification
Function description
Wattmetric-based earth-fault pro-
tection
4.2.6.2 Function block
Figure 186: Function block
4.2.6.3 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.
3 Start value = 2.5 × I
Maximum
376
Value
Typically 0.96
±1.0% of the set value or ±20 ms
3
±5.0% of the set value or ±20 ms
-50 dB at f = f
-3 dB at f = 13 × f
IEC 61850
identification
WPWDE
Start value multiples in range of 2...20
,
n
n
n
IEC 60617
identification
Po> ->
1MRS758755 C
ANSI/IEEE C37.2
device number
32N
REC615 & RER615
Technical Manual