![Schweitzer Engineering Laboratories SEL-421-4 Скачать руководство пользователя страница 445](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_1216726445.webp)
6.109
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Applications Examples
EHV Parallel 230 kV Underground Cables Example
The technical paper
Underground/Submarine Cable Protection Using a Sequence
Directional Comparison Scheme
(see selinc.com for a copy of this paper) pro-
Equation 6.68
to calculate the apparent negative-sequence
impedance during unbalanced faults:
Equation 6.69
yields a more conservative result for the negative-sequence imped-
ance when the parallel cable is out of service:
|Z2S| = 2.97
is greater than the default setting for Z2R;
Z2R = (Z2F + 1/(2 • I
NOM
). (See
Ground Directional Elements on page 1.18
for
more information.)
Figure 6.27
Reverse Unbalanced Fault on Cable Circuit (Shunt Admittance)
Z1L1
Z1R
Z1S
S
R
Z1L1
R
Z1R
Z1S
I2
I2
I2S
I2R
I2
V2
S
Y1L1
2
Y1L1
2
Impedance Diagram
Negative-Sequence Network
SEL-421
Z
2S
V
2S
–
I
2S
-------------
=
4 Z
1L1
2
+
Y
1L1
Z
1L1
Z
1R
4
+
Z
1R
• •
•
• •
4 4 Y
1L1
Z
1R
2
+
Y
1L1
Z
1L1
Y
2
1L1
+
Z
1L1
Z
1R
• •
• •
• •
+
----------------------------------------------------------------------------------------------------------------------------------------------------------
=
3.86
=
z2
Re V
2
I
2
Z1ANG
•
•
*
I
2
2
----------------------------------------------------------------------
=
Содержание SEL-421-4
Страница 6: ...This page intentionally left blank ...
Страница 14: ...This page intentionally left blank ...
Страница 30: ...This page intentionally left blank ...
Страница 104: ...This page intentionally left blank ...
Страница 128: ...This page intentionally left blank ...
Страница 536: ...This page intentionally left blank ...
Страница 584: ...This page intentionally left blank ...
Страница 616: ...This page intentionally left blank ...
Страница 696: ...This page intentionally left blank ...
Страница 750: ...This page intentionally left blank ...
Страница 755: ...Instruction Manual PM400 01 NB SEL 400 Series Relays Instruction Manual 20171006 ...
Страница 776: ...This page intentionally left blank ...
Страница 932: ...This page intentionally left blank ...
Страница 976: ...This page intentionally left blank ...
Страница 1024: ...This page intentionally left blank ...
Страница 1038: ...This page intentionally left blank ...
Страница 1064: ...This page intentionally left blank ...
Страница 1128: ...This page intentionally left blank ...
Страница 1206: ...This page intentionally left blank ...
Страница 1316: ...This page intentionally left blank ...
Страница 1350: ...This page intentionally left blank ...
Страница 1464: ...This page intentionally left blank ...
Страница 1468: ...This page intentionally left blank ...
Страница 1492: ...This page intentionally left blank ...
Страница 1518: ...This page intentionally left blank ...