ABB RELION REX640 - Page 1296

Impedance
calculation
LB_FORWARD
I3P
I_A
I_B
I_C
U3P
U_A_AB
U_B_BC
U_C_CA
BLOCK
I1
Load
impedance
zone check
LB_REVERSE
I2
U1
Figure 735: Functional module diagram
Impedance calculation
The impedance calculation is enabled if the negative sequence current stays below
the Max Ng Seq current setting and the positive sequence voltage stays above the
Min Ps Seq voltage setting.
The positive sequence impedance phasor
1
Z
-
is calculated according to:
1
1
1
U
Z =
I
-
-
-
(Equation 312)
where
1
U
-
is positive sequence voltage phasor and
1
I
-
is positive sequence current
phasor.
The calculated positive sequence impedance amplitude Z1_AMPL (primary ohms)
and angle Z1_ANGLE (degrees) are available in monitored data view.
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 Max
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 Resistive reach Fw is maximum resistive load on forward load blinder
area. Resistive reach Rv is maximum resistive load on reverse load blinder area.
Characteristics are shown Figure 736 .
Protection related functions
1MRS759142 F
1296 REX640
Technical Manual