Schweitzer Engineering Laboratories SEL-351-5, Инструкция по эксплуатации, Страница: 162 / 706

4.18
SEL-351-5, -6, -7 Relay Instruction Manual
Date Code 20070117
Loss-of-Potential, Load Encroachment, and Directional Element Logic
Directional Control for Neutral Ground and Residual Ground Overcurrent Elements
In most communications-assisted trip schemes, the levels are set as follows
(see
Figure 5.4 ):
➤
Level 1 overcurrent elements set direction forward (DIR1 = F)
➤
Level 2 overcurrent elements set direction forward (DIR2 = F)
➤
Level 3 overcurrent elements set direction reverse (DIR3 = R)
If a level direction setting (e.g., DIR1) is set:
DIR1 =
N
(nondirectional)
then the corresponding Level 1 directional control outputs in Figure 4.17 and
Figure 4.18 assert to logical 1. The referenced Level 1 overcurrent elements in
Figure 4.17 and Figure 4.18 are then not controlled by the directional control
logic.
See the beginning of Directional Control Settings on page 4.38 for discussion
of the operation of level direction settings DIR1 through DIR4 when the
directional control enable setting E32 is set to E32 = N.
In some applications, level direction settings DIR1 through DIR4 are not
flexible enough in assigning the desired direction for certain overcurrent
elements.
Directional Control Provided by Torque Control Settings on
page 4.57 describes how to avoid this limitation for special cases.
q From Figure 4.1 ; w from Figure 4.7 ; e to Figure 4.9 and Figure 4.20 ; r to
Figure 4.20 and Figure 4.21 ; t to Figure 4.9 , Table 4.1 , and Table 4.2 .
Figure 4.6 Internal Enables (32QE and 32QGE) Logic for Negative-Sequence
Voltage-Polarized Directional Elements
|3I
2
|
|I
2
|
a2 • |I
1
|
k2 • |I
0
|
|I
2
|
Setting
Settings
50QFP
50QRP
50QR
50QF
32VE
32IE
Setting
e
32QE
(Internal Enable)
r
"Q" Listed in
Setting ORDER
Setting Enable
t
32QGE
(Internal Enable)
(I
0
= I
G/3
)
q
w
LOP
ELOP = Y or Y1
Loss-of-Potential
Setting
VNOM = OFF
Relay
Word
Bits
Relay
Word
Bit
Relay
Word
Bits