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REF 610
132
Feeder Protection Relay
Technical Reference Manual
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.
When using a 4-wire bus, one pair is connected to +RX and -RX and the other to
+TX and -TX. If signal ground is being used, a quality cable with three or several
pairs is to be used and one of the conductors of a pair connected to signal ground.
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 DNP interfaces.
The DNP 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 DNP communication
module. The termination resistor is selected by setting jumper X6 or/and X12 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 X8, X7, X13 and
X11 to the ON position.
The jumpers have been set to no termination (X5 in the OFF position) and no biasing
(X8, X7, X13 and X11 in the OFF position) as default.
Table 4.2.3-6
RS-485 rear connector (DNP 3.0)
Terminal
Function
X5.8-8
Data A (+ RX)
X5.8-7
Data B (- RX)
X5.8-6
Data A (+ TX)
X5.8-5
Data B (- TX)
X5.8-4
Signal GND (for potential balancing)
X5.8-3
-
X5.8-2
Shield GND (via capacitor)
X5.8-1
Shield GND
1MRS 755310
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