ABB RELION REX640 Technical Manual page 1040

Protection functions
Impedance calculation
This module receives positive sequence voltage (U
(U ) which are calculated from fundamental frequency three phase voltages.
2
Also positive sequence current (I
respectively calculated from fundamental frequency three phase currents.
Once activated the negative sequence impedance (Z
negative sequence current, the negative sequence voltage and Relay characteristic
angle (RCA) using the below equation.
The RCA in the above equation can be obtained from
The Z
Table 972: Direction value for monitored data view
Criterion for direction information
Default (low level blocking active)
Z > 0
2
Z < 0
2
Fault direction detector
This module checks if the value of Z
forward direction can be achieved by setting the
forward fault is detected if the value of Z
setting. Respectively operation to only reverse direction can be activated by setting
Direction mode is set to "Reverse". Reverse fault is detected if the value of Z
below the setting
"Non-directional", operation is allowed if condition for forward or reverse direction
is fulfilled.
FAULT_DIR gives the direction information during fault, if operation criteria is
satisfied. that is, when the START output is active. The fault direction (FAULT_DIR) is
available in monitored data and as function block output. FAULT_DIR values are the
same as for DIRECTION output given in the
0 = unknown after the START output is deactivated.
Figure 579
impedance level as shown in the vertical line.
1040
value in primary ohms is available as Z2_VALUE in monitored data.
2
Ng Seq impedance Rv setting. In case Direction mode is set to
Ng Seq impedance Fw setting and Ng Seq impedance Rv settings are
The
set in primary ohms.
illustrates the directional operating characteristics on negative sequence
) and negative sequence voltage
1
) and negative sequence current (I
1
) is calculated from the
2
Characteristic angle setting.
The value for DIRECTION
0 = unknown
1 = forward
2 = backward
meets the operation criteria. Detection to only
2
Direction mode to "Forward". Thus,
is higher than the
2
Table 972
. The FAULT_DIR is set to value
1MRS759142 F
) which are
2
(Equation 278)
Ng Seq impedance Fw
is
2
REX640
Technical Manual