Comander Perimeter Security System
Engineering and Installation Manual
Page 64 of 72
5.5.7 Connecting A Large Number of Zones
When feeder cables of up to twenty pairs are used, Geoquip can supply junction boxes
with terminal blocks fitted to facilitate the daisy-chaining of the cables ...
An alternative version suitable for the connection of four Interceptor cables is also
available. This would be used when Dual Zones are implemented and separate Upper
and Lower sensor runs are to be connected from each of the two zones at the junction
box.
The multi-way Krone Connector Block provides an easy way to connect the incoming
feeder pairs carrying existing sensor or tamper signals to the appropriate pairs of the
outgoing feeder
5.6 Testing the Sensor Installation
Once the sensor is attached to the fence and connected to its End-Of-Line termination,
it is possible to test the integrity of the installation even before the electronics is
installed. It is in fact advisable to test each connection in a chain as it is installed (see
“Testing Feeder Connections” above). The following test procedure should be followed:
• The EOL termination used in Comander systems is a 4k7Ω resistor in parallel
with a capacitor for AC signal bypass.
• A simple multimeter may be used to test the loop resistance of the Interceptor
cable after installation. Set the meter to auto-range resistance metering and
connect its probes to the appropriate pair of the feeder cable carrying the
relevant sensor signal - the reading may briefly be unstable but should settle to
around 4k7Ω after a couple of seconds.
• If the resistance measured is significantly lower than 4k7Ω then there is a short
circuit somewhere in the installed wiring.
• If the resistance measured is significantly higher than 4k7Ω then there is a poor
connection or an open circuit somewhere in the installed wiring.
Note that the long runs of feeder cable often used in Comander installations will
increase the loop resistance by a few hundred ohms, but this should not significantly
affect the readings taken.
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