ABB REF 610 Technical Reference Manual page 129

1MRS 755310 Feeder Protection Relay
Technical Reference Manual
Plastic fibre-optic connection
If REF 610 is provided with the optional fibre-optic communication module for
plastic fibre, the fibre-optic cables are connected to terminals X5.3-RX (Receiver)
and X5.3-TX (Transmitter).
Table 4.2.3-1 Plastic fibre-optic rear connector
Terminal Function
X5.3-TX Transmitter
X5.3-RX Receiver
RS-485 connection
If REF 610 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 REF 610 is being used is 32, and the maximum length of the bus is
1200 meters.
When connecting REF 610 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).
Note!
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 module.
The termination resistor is selected by setting jumper X5 to the ON position. If the
internal termination resistor of 120 Ω is used, the impedance of the cable should be
the same.
The bus is to be biased at one end to ensure fail-safe operation, which can be done
using the pull-up and pull-down resistors on the communication module. The
pull-up and pull-down resistors are selected by setting jumpers X3 and X4 to the ON
position.
The jumpers have been set to no termination (X5 in the OFF position) and no biasing
(X3 and X4 in the OFF position) as default.
REF 610
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