ABB RELION REX640 Technical Manual page 1296

Protection related functions
Figure 735: Functional module diagram
Impedance calculation
The impedance calculation is enabled if the negative sequence current stays below
the
Min Ps Seq voltage setting.
The positive sequence impedance phasor

Z =
1
where
phasor.
The calculated positive sequence impedance amplitude
and angle
The calculated impedance is converted to primary ohms as the operating
characteristics are defined with settings in primary ohms.
Load impedance zone check
The forward and reverse load blinder sectors are defined separately. The load
blinder forward area, or load-out region, or load exporting is limited with the
impedance angle and Min impedance angle . Similarly, these two setting parameters
are also as limitations for the load blinder reverse area, or load-in region, or load
importing. the
area.
Characteristics are shown
1296
I_A
I_B
I_C
I3P
I1
I2
U_A_AB
U_B_BC
U3P
U_C_CA
U1
BLOCK
Max Ng Seq current setting and the positive sequence voltage stays above the

U
1

I
1

U
is positive sequence voltage phasor and
1
Z1_ANGLE (degrees) are available in monitored data view.
Resistive reach Fw is maximum resistive load on forward load blinder
Resistive reach Rv is maximum resistive load on reverse load blinder area.
Impedance
impedance
calculation
zone check

Z
is calculated according to:
1
Figure 736
.
1MRS759142 F
LB_FORWARD
Load
LB_REVERSE
(Equation 312)

I
is positive sequence current
1
Z1_AMPL (primary ohms)
Technical Manual
Max
REX640