Rear communication of the relay is optional and the physical connection varies with
the communication option.
Plastic fibre-optic connection
If the relay is provided with the optional fibre-optic communication module for
plastic fibre, the fibre-optic cables are connected to terminals as follows:
Table 5.2.3.-1 Plastic fibre-optic rear connection
Terminal Function
X5.3-TX Transmitter
X5.3-RX Receiver
RS-485 connection
If the relay is provided with the optional RS-485 communication module, the cable
is connected to terminals X5.5/1-2 and X5.5/4-6. The connection socket is a 6-pin
header-type socket and the terminals are of screw compression type.
The RS-485 communication module follows the TIA/EIA-485 standard and is
intended to be used in a daisy-chain bus wiring scheme with 2-wire, half-duplex,
multi-point communication.
The maximum number of devices (nodes) connected to the bus where
the relay is being used is 32, and the maximum length of the bus is
1200 meters.
When connecting the relay to the bus, a quality twisted pair shielded cable is to be
used. The conductors of the pair are connected to A and B. If signal ground is being
used for balancing potential differences between devices/nodes, a quality dual
twisted pair shielded cable is to be used. In this case, one pair is connected to A and
B, and one of the conductors of the other pair to signal ground. When connecting
one device to another, A is connected to A and B to B.
The cable shield is to be connected directly to earth (shield GND) in one point/
device of the bus. Other devices connected to the bus should have the cable shield
connected to earth via a capacitor (shield GND via capacitor).
Signal ground can only be used for balancing potential differences
between devices/nodes if all devices connected to the bus have isolated
RS-485 interfaces.
The RS-485 communication module is provided with jumpers for setting bus
termination and fail-safe biasing. The bus is to be terminated at both ends, which
can be done by using the internal termination resistor on the communication
142
REF 610REF 610
Feeder Protection Relay
Technical Reference Manual
1MRS755310
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