ABB Relion 670 series, Руководство по применению, Страница: 222 / 760

RFFwPE Z
load
≤ ⋅ 1 6 .
IEC13000275 V1 EN-US
(Equation 165)
Equation 165 is applicable only when the loop characteristic angle for the phase-to-phase
faults is more than three times as large as the maximum expected load-impedance angle. More
accurate calculations are necessary according to equation 166 .
RFFwPP Z
R
X
load
≤ ⋅ ⋅ ∂ − ⋅ ∂






1 6
1
1
. cos sin
min
IEC13000276 V1 EN-US
(Equation 166)
Set the fault resistance coverage RFRwPP and RFRwPE to the same value as in forward
direction, if that suits the application. All this is applicable for all measuring zones when no
Power swing detection function ZMRPSB is activated in the IED. Use an additional safety
margin of approximately 20% in cases when a ZMRPSB function is activated in the IED, refer to
the description of Power swing detection function ZMRPSB.
7.3.3.8 Load impedance limitation, with Phase selection with load
encroachment, quadrilateral characteristic function activated
SEMOD55087-138 v5
The parameters for shaping of the load encroachment characteristic are found in the
description of Phase selection with load encroachment, quadrilateral characteristic function
(FDPSPDIS).
7.3.3.9 Setting of minimum operating currents
SEMOD55087-141 v5
The operation of Distance protection zone, quadrilateral characteristic (ZMQPDIS) can be
blocked if the magnitude of the currents is below the set value of the parameter
IMinOpPP and
IMinOpPE.
The default setting of
IMinOpPP and IMinOpPE is 20% of IBase where IBase is the chosen
current for the analogue input channels. The value has been proven in practice to be suitable in
most of the applications. However, there might be applications where it is necessary to
increase the sensitivity by reducing the minimum operating current down to 10% of IBase. This
happens especially in cases, when the IED serves as a remote back-up protection on series of
very long transmission lines.
Setting
IMinOpIN blocks the phase-to-earth loop if 3I
0
<
IMinOpIN. The default setting of
IMinOpIN is 5% of IBase.
The minimum operating fault current is automatically reduced to 75% of its set value, if the
distance protection zone has been set for the operation in reverse direction.
7.3.3.10 Directional impedance element for quadrilateral characteristics
M16923-139 v6
The evaluation of the directionality takes place in Directional impedance quadrilateral function
ZDRDIR. Equation 167 and equation 168 are used to classify that the fault is in forward
direction for phase-to-earth fault and phase-to-phase fault.
1 1
1
0.8 1 0.2 1
arg Re L L M
L
U U
ArgDir ArgNeg s
I
× + ×
- < <
EQUATION725 V2 EN-US
(Equation 167)
For the L1-L2 element, the equation in forward direction is according to.
Section 7 1MRK 505 343-UEN B
Impedance protection
216
Application manual