Schweitzer Engineering Laboratories, Inc. SEL-787-3, -4 Data Sheet
19
Additional Features
MIRRORED BITS Relay-to-Relay
Communications
The SEL-patented MIRRORED BITS
®
communications
technology provides bidirectional relay-to-relay digital
communication. M
IRRORED BITS communications can
operate independently on as many as two EIA-232 rear
serial ports and one fiber-optic rear serial port on a single
SEL-787.
This bidirectional digital communication creates eight
additional virtual outputs (transmitted M
IRRORED BITS)
and eight additional virtual inputs (received M
IRRORED
BITS) for each serial port operating in the MIRRORED
BITS mode (see Figure 16). Use these MIRRORED BITS to
transmit/receive information between upstream relays
and a downstream relay to enhance coordination and
achieve faster tripping for downstream faults. M
IRRORED
BITS technology also helps reduce total scheme
operating time by eliminating the need to assert output
contacts to transmit information.
Figure 16 MIRRORED BITS Transmit and Receive Bits
Status and Trip Target LEDs
The SEL-787 includes 24 tricolor status and trip target
LEDs on the front panel. When shipped from the factory,
all LEDs are predefined and fixed in settings. You can
reprogram these LEDs for specific applications. This
combination of targets is explained and shown in
Figure 18. Some front-panel relabeling of LEDs may be
needed if you reprogram them for unique or specific
applications—see Configurable Labels.
Event Messenger Points
The SEL-787, when used with the SEL-3010 Event
Messenger, can allow for ASCII-to-voice translation of
as many as 32 user-defined messages, along with analog
data that has been measured or calculated by the relay.
This combination allows you to receive voice message
alerts (on any phone) regarding Relay Word bit transi-
tions in the relay.
Verbal notification of breaker openings, fuse failures,
RTD alarms, etc. can now be sent directly to your cell
phone through the use of your SEL-787 and SEL-3010
(must be connected to an analog telephone line). In
addition, messages can include an analog value such as
current, voltage, or power measurements made by the
SEL-787.
Configurable Labels
Use the configurable labels to relabel the operator con-
trols and LEDs (shown in Figure 18) to suit the installa-
tion requirements. This feature includes preprinted labels
(with factory-default text), blank label media, and a Mic-
rosoft
®
Word template on CD-ROM. This allows quick,
professional-looking labels for the SEL-787. Labels may
also be customized without the use of a PC by writing the
new label on the blank stock provided. The ability to cus-
tomize the control and indication features allows specific
utility or industry procedures to be implemented without
the need for adhesive labels.
Additional Ordering Options
The following options can be ordered for the SEL-787
model (see the SEL-787-3,-4 Model Option Table for
details).
➤ Single or dual port Ethernet 10/100BASE-T or
100BASE-FX, Modbus TCP, SNTP, DNP3 Serial,
DNP3 LAN/WAN, FTP, Telnet, IEC 61850,
IEC 60870-5-103
➤ EIA-232 or EIA-485 communications
➤ Additional EIA-232 or EIA-485 port
➤ Analog I/O (4 AI/4 AO)
➤ Digital I/O (4 DI/4 DO, 8 DI, 8 DO, 3 DI/4 DO/1 AO,
4 DI/3 DO)
➤ Voltage input for synchronism check/station DC bat-
tery monitor
➤ 10 RTDs
➤ Conformal coating for chemically harsh and high-
moisture environments
➤ The relay supports the Spanish language as an order-
ing option.
SEL-787
Transmit
Receive
Transmit
Receive
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Relay 2
0
0
0
1
0
0
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1
0
0
0
0
0
TMB1
TMB2
TMB8
RMB1
RMB2
RMB8 RMB8
TMB1
TMB2
TMB8
.
.
.
.
.
.
RMB1
RMB2
.
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