P.2.42
SEL-411L Relay Protection Manual Date Code 20151029
Installation
Connection
Rear Panel TX/RX LED
Each channel interface has two rear-panel LEDs that can help in the
troubleshooting of installation problems. The RX LED illuminates when the
channel is enabled and receives packets from another relay. The RX LED
extinguishes if the channel is impaired for any of the following.
➤ There are sufficient data errors to prevent the relay from
recognizing the packet boundaries
➤ The receive data are entirely absent
➤ The externally supplied RX clock stops (in the case of an
EIA-422 port)
Serial Cables
Using an improper cable can cause numerous problems or failure to operate,
so you must be sure to specify the proper cable for application of your relay.
Several standard SEL communications cables are available for use with the
relay. See EIA-232 Communications Cables on page C.1.3 for information on
recommended serial cables.
The following list provides additional rules and practices you should follow
for successful communication using EIA-232 serial communications devices
and cables:
➤ Route communications cables well away from power and
control circuits. Switching spikes and surges in power and
control circuits can cause noise in the communications circuits
if power and control circuits are not adequately separated from
communications cables.
➤ Keep the length of the communications cables as short as
possible to minimize communications circuit interference and
also to minimize the magnitude of hazardous ground potential
differences that can develop during abnormal power system
conditions.
➤ Ensure that EIA-232 communications cable lengths never
exceed 50 feet, and always use shielded cables for
communications circuit lengths greater than 10 feet.
➤ Modems provide communication over long distances and give
isolation from ground potential differences that are present
between device locations (examples are the SEL-28XX-series
transceivers).
➤ Lower data speed communication is less susceptible to
interference and will transmit greater distances over the same
medium than higher data speeds. Use the lowest data speed that
provides an adequate data transfer rate.
Severe power and ground problems
can occur on the communications
ports of this equipment as a result of
using non-SEL cables. Never use
standard null-modem cables with this
equipment.
To Next Page
Loading...
