ABB RELION REX640 Technical Manual page 1043

1MRS759142 F
Ng Seq impedance Fw can be set to 50% of the Z
•
which equals in primary ohms 60.4/2 = 30.2.
Ng Seq impedance Rv can be set to 50% of the Z
•
Setting is for reverse fault in parallel line and therefore magnitude is negative.
Thus setting value is in primary ohms -60.4/2 = -30.2.
• If
angle setting can be calculated as below.
Characteristic angle = arctan(X/R)
The setting
in the power system network. In this case 10% unbalance is allowed in the given
example system, hence the
Fault simulation
The phase to ground faults are simulated in the given example shown in
the relay is located at the sending end of the line1 and the output is captured for
forward and reverse direction fault.
The phase A to ground fault is applied on the line1 in the forward direction, the Z
value is positive as well as exceeds the
hence the START output issued, FAULT_DIR indicates the fault in the forward
direction and the OPERATE output will be issued after the
setting has passed as shown in below
Figure 581: Phase A to ground fault on forward direction
The phase A to ground fault is applied on the line2 in the reverse direction, the
calculated Z
threshold, hence the START output issued, FAULT_DIR indicates the fault in the
reverse direction and the OPERATE output will be issued after the
time setting has passed as shown in below
REX640
Technical Manual
Characteristic angle mode is set to "Fixed", then the value for Characteristic
= arctan(60.1/12.6)
= 78.3 deg
Restrain factor is set based on the minimum unbalance loading allowed
value is negative as well as lower the
2
Restrain factor is set to 0.1.
Ng seq impedance Fw setting threshold,
Figure 581
.
Figure 582
Protection functions
tot magnitude of the line 1
1
tot magnitude of the line 2.
1
(Equation 280)
Operate delay time
Ng seq impedance Rv setting
Operate delay
.
Figure 580
,
2
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