2.19
Date Code 20150130 Instruction Manual SEL-787 Relay
Installation
Rear-Panel Connections
Figure 2.11 DeviceNet, Fast Hybrid 4 DI/4 DO, and Current/Voltage Option
Power Connections
The POWER terminals on the rear panel (A01 (+/H) and A02 (—/N)) must connect
to 110–240 Vac, 110–250 Vdc, or 24–48 Vdc (see Power Supply on page 1.9
for complete power input specifications). The POWER terminals are isolated
from chassis ground. Use 14 AWG (2.1 mm
2
) to 16 AWG (1.3 mm
2
) size wire
to connect to the POWER terminals.
For compliance with IEC 60947-1 and IEC 60947-3, place a suitable external
switch or circuit breaker in the power leads for the SEL-787; this device
should interrupt both the hot (+/H) and neutral (-/N) power leads. The
maximum current rating for the power disconnect circuit breaker or optional
overcurrent device (fuse) should be 20 A.
Operational power is internally fused by a power supply fuse. See Field
Serviceability on page 2.31 for details. Be sure to use fuses that comply with
IEC 60127-2.
Grounding (Earthing)
Connections
You must connect the ground terminal labeled GND on the rear panel to a rack
frame or switchgear ground for proper safety and performance. Use 14 AWG
(2.1 mm
2
) wire less than 2 m (6.6 feet) in length for the ground connection.
Serial Ports
Because all ports (F, 2, 3, and 4) are independent, you can communicate to any
combination simultaneously. Although serial Port 4 on the optional
communications card consists of an EIA-485 (4A) and an EIA-232 (4C) port,
only one port is available at a time. Use the Port 4 communications interface
COMMINF setting to select between EIA-485 and EIA-232.
The serial port EIA-485 plug-in connector accepts wire size AWG 24 through
AWG 12. Strip the wires 8 mm (0.31 inches) and install with a small slotted-
tip screwdriver. All EIA-232 ports accept 9-pin D-subminiature male
connectors.
For connecting devices at distances over 100 feet, where metallic cable is not
appropriate, SEL offers fiber-optic transceivers or the SEL-2812 compatible
PORT 2
TX RX
1
9
PORT 3
PORT 1A PORT 1B
(A) Rear-Panel Layout (B) Side-Panel Input and Output Designations
Contact with instrument terminals can
cause electrical shock that can result
in injury or death.
The relay contains devices sensitive to
Electrostatic Discharge (ESD). When
working on the relay with the front
panel removed, work surfaces and
personnel must be properly grounded
or equipment damage may result.
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