31
Installing the communication cables
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When using galvanic connection between protection terminal and communication
equipment or point to point galvanic connection between two protection terminals it is
essential that the cable installation is carefully done. This is true regardless of type of
module used, G.703, V.36, short range galvanic etc., only the possible length of the ca-
ble differs. The factors that must be taken into account are the susceptibility for noise
disturbance, due to that the levels of the communication signal are very low.
For best result a cable with twisted pairs and double screens should be used, one screen
for each twisted pair and one surrounding all pairs. Each signal shall utilizie its own
twisted pair as in figure
. The screen for each separate pair shall be connected to inter-
nal screen or ground connection of equipment in one and the same end only, if avail-
able, or in other case connected to earth close to the equipment.
The outer screen surrounding all pairs shall be connected to a solid earth at
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end
close to the equipment.
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Cc
Communication cable
Lc
Line connector
Rx
Receive input
Sc
Screen (or earth/ground) connection
Tx
Transmit output
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Rx
Tx
Sc
Lc
Tx
Rx
Sc
Lc
Cc
Relay
Terminal
External
Equipment
Summary of Contents for REL 531
Page 16: ...10 Note signs KDSWHU 6DIHW LQIRUPDWLRQ ...
Page 44: ...38 Checking the binary I O circuits KDSWHU KHFNLQJ WKH H WHUQDO FLUFXLWU ...
Page 52: ...46 Checking the self supervision signals KDSWHU QHUJLVLQJ WKH WHUPLQDO ...
Page 140: ...134 Testing the interaction of the distance protection KDSWHU 7HVWLQJ WKH SURWHFWLRQ V VWHP ...
