ABB Relion 670 series - Page 351

The calculated R
calc
and X
calc
are compared with the non-directional phase-to-phase quadrilateral
characteristics defined by the reactance reaches ( X1FwPPZx and X1RvPPZx , where x = 1 to 5 or RV),
resistance reaches ( R1FwPPZx , where x = 1 to 5 or RV) for the zones, as well as the fault resistance
reach setting for phase-to-phase loops (( RFPPZx , where x = 1, 2 or RV), ( RFFwPPZx and RFRvPPZx ,
where
x = 3 to 5 or RV)), as shown in Figure 174. If is inside the non-directional phase-to-phase
characteristic, the STNDZx output is set to TRUE.
For phase-to-ground faults (Figure 175, upper part), the ground return compensation applies
according to Equation 98 (example for a phase L1 to ground fault).


11 0
31
LLN F
UIKIpZIRF
IECEQUATION18007 V1 EN-US (Equation 98)
Where,
p is the fault location and RF is the calculated fault resistance. p and RF are unknown and needs to
be solved.
is the zero-sequence current.
is the ground compensation factor and it is defined as:
01
31
00 0
11 1
N
ZZ
K
Z
Z
R FwPEZx j X FwPEZx
Z
R FwPEZx j X FwPEZx





IECEQUATION18020 V1 EN-US
Where,
is the set complex zero sequence impedance of the line in Ω/phase.
is the set complex positive sequence impedance of the line in Ω/phase.
R1FwPEZx is the positive sequence resistive reach of the line in Ω/phase for phase-to-ground fault
in zone direction for zone x ( x = 1 to 5 or RV).
X1FwPEZx is the positive sequence reactance reach of the line in Ω/phase for phase-to-ground
fault in zone direction for zone x ( x = 1 to 5 or RV).
R0FwPEZx is the zero sequence resistive reach of the line in Ω/phase for phase-to-ground fault in
zone direction for zone x ( x = 1 to 5 or RV).
X0FwPEZx is the zero sequence reactance reach of the line in Ω/phase for phase-to-ground fault in
zone direction for zone x ( x = 1 to 5 or RV).
is the fault current. It is chosen among phase, zero or negative sequence currents automatically
by the built-in adaptive load compensation algorithm.
The calculated impedances from the relay to the fault

calc calc calc
Z
RjX
can be represented as:
1
1
calc
calc
X p X FwPEZx
R
p R FwPEZx RF

 
IECEQUATION18021 V1 EN-US
1MRK 502 066-UUS B Section 7
Impedance protection
345
Technical manual