NR Electric PCS-9611, Instruction Manual

Page: 66 / 300

3 Operation Theory
PCS-9611 Feeder Relay
3-30
Date: 2014-04-08
The sensitive earth fault relay characteristic angle (SEF-RCA) is configurable through the setting
[50/51SEF.RCA]. A directional check is performed based on the following criteria:

Directional forward
-90° < (angle(U
0
) - angle(I
0S
) - SEF-RCA) < 90°

Directional reverse
-90° > (angle(U
0
) - angle(I
0S
) - SEF-RCA) > 90°
Forward
Reverse
O
U
0
I
0S
SEF-RCA
Figure 3.6-3 Operation characteristic of the SEF directional element
The setting [50/51SEFx.Opt_Dir] (x: 1~4) is used to select the directional mode for the stage x (x:
1~4) sensitive earth fault protection respectively.
Setting Value 0 1 2
Directional Mode Non-directional Forward directional Reverse directional
When the element is selected as directional, a VTS block option is available. When the relevant
setting is set as
“1”, operation of the voltage transformer supervision (VTS) will block the stage if
the relevant directional element is in service. When the relevant setting is set as
“0”, the stage will
revert to non-directional upon operation of the VTS.
The detailed logic diagram of the directional element of the stage 1 sensitive earth fault protection
is shown as below.
[VTS.En]
[50/51SEF.En_VTS_Blk]
[VTS.Alm]
I
0S
(present measure)
U
0
(present measure)
[50/51SEF1.Opt_Dir] ≠ 0
SEF
Direction Check
&
50/51SEF1.Dir
[ BI_En_VT ]
Figure 3.6-4 Logic diagram of the directional element for the stage 1 SEF protection
Where:
[50/51SEF1.Opt_Dir] is the setting which is used to select the directional mode
(non-directional, forward, reverse) of the directional element for the stage 1 SEF protection;