Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 57 / 706

2.17
Date Code 20070117
Instruction Manual SEL-351-5, -6, -7 Relay
Installation
Making Rear-Panel Connections
To verify the correct polarity on voltage input
VS
, perform the following test
on the primary side of one of the PTs connected in broken-delta secondary
(refer to
Figure 2.8 ) and observe the resultant voltage phase angle differences.
Open circuit the primary side of the PT connected to power system phase
A. With the resultant collapse of secondary voltage V
A
(V
A
= 0) in the
broken-delta secondary circuit, the voltage at voltage input
VS
is:
V
S
= 3V
0
= V
A
+ V
B
+ V
C
= V
B
+ V
C
Figure 2.9 shows the resultant voltage V
S
, with respect to the delta-
connected power system voltages connected to the voltage inputs
VA
,
VB
,
VC
(ABC rotation used in this example). For this scenario of the collapse
of secondary voltage V
A
(V
A
= 0) in the broken-delta secondary, note that
voltage V
S
is 150 degrees out-of-phase with voltage V
AB
(from voltage
input
VA
).
Use the METER command (via serial port or front panel) to compare
these voltage phase angles. If the phase angle difference between V
S
and
V
A
is 150 degrees (within a few degrees), then the polarity of voltage
input
VS
is deemed correct. If the phase angle difference between V
S
and
V
A
is 30 degrees (again, within a few degrees), then the secondary wires
from the broken-delta secondary in Figure 2.8 need to be swapped in
connection to terminals VS-NS .
The relay will use voltage V
AB
as the phase angle reference (zero
degrees) when a sufficient voltage signal is present. The phasors in
Figure 2.9 could have been drawn rotated clockwise by 30 degrees.
Figure 2.9 Resultant Voltage V
S
from the Collapse of Voltage V
A
in the
Broken-Delta Secondary (Compared to the Delta-Connected Power System
Voltages)
Serial Ports
Refer to Table 10.1 for information on the serial ports available on the
different SEL-351 models. All ports are independent—you can communicate
to any combination simultaneously.
SERIAL PORT 1
on all the SEL-351 models is an EIA-485 port (4-wire). The
SERIAL PORT 1
plug-in connector accepts wire size AWG 24 to 12. Strip the
wires 0.31 inches (8 mm) and install with a small slotted-tip screwdriver. For
models 0351
x 0, 0351 x 1, and 0351 x Y, the SERIAL PORT 1 connector has extra
positions for IRIG-B time-code signal input (see Table 10.3 ; see following
discussion on IRIG-B time code input).
All EIA-232 ports accept 9-pin D-subminiature male connectors. PORT 2 on all
the SEL-351 models includes the IRIG-B time-code signal input (see
Table 10.2 ; see following discussion on IRIG-B time code input).
The pin definitions for all the ports are given on the relay rear panel and
detailed in
Table 10.2 – Table 10.4 .
Refer to Table 2.1 for a list of cables available from SEL for various
communication applications. Refer to Section 10: Serial Port
Communications and Commands for detailed cable diagrams for selected
cables (cable diagrams precede Table 10.4 ).
V
CA
V
BC
V
AB
V
S
NOTE:
When the relay is connected
to open-delta PTs and Global setting
PTCONN = DELTA, there is no “3V0”
value in the
METER command (via serial
port or front panel).
NOTE:
Listing of devices not
manufactured by SEL in Table 2.1 is for
the convenience of our customers.
SEL does not specifically endorse or
recommend such products, nor does
SEL guarantee proper operation of
those products, or the correctness of
connections, over which SEL has no
control.