CIE-A-200 Control Panel Engineering and Commissioning Manual
59
Loop Open Circuit
If random or recurrent Loop O/C faults are reported then check the entire system for the
following:
Loose connections
. Ensure all terminals are tight.
Broken Connectors.
If the terminal is over-tightened the main body of the
connector may become broken, causing an intermittent open circuit.
Broken or missing copper connecting strips (Original style Multipoint only
–
not ASD).
The connection from the connector body to the pin which links to the
Multipoint detector is made by the copper connecting strip which may be seen
entering the connector with the cable. Ensure that these are not broken off or bent
out of place as this will cause an intermittent open circuit.
Broken cables.
Ensure that the cables are not snapped off before they enter the
connector.
A cable may seem to be connected, but not actually make a contact.
Trapped insulation.
Ensure that the cable insulation is not trapped in the
connector, stopping it from making a connection.
The entire system should be carefully checked for the above, as a cumulative effect may
take place if a number of high resistance connections are present, causing random
reporting of the location of the problem.
IMPORTANT NOTE
If short circuit or open circuit faults occur on the loop wiring the panel will detect these faults and
indicate this with the yellow loop fault LED. These faults will also get logged in the event logs.
The adjacent devices on the loop will open their isolators to isolate the section of cable which is in
fault. The panel will use both ends of the loop to communicate with the devices so no devices are
lost.
In these cases as no devices are lost the faults may appear to clear but it is most important to check
the fault LEDs and event logs on the panel.
When cable faults occur, the loop MUST BE STOPPED manually and the faults investigated and
rectified before re-initialising the loop again. Do not attempt to rectify a cable fault or to remove and/or
reinsert devices into a live loop.
Some loop devices may be lost under certain short circuit/open circuit conditions depending on the
nature and position of the fault. Any devices affected will be reported as in fault on the panel.
Note: When the devices open their isolators due to loop faults, the device isolators are latched.
The loop MUST BE STOPPED & RE-INITIALISED in order to close the device isolators and
reset the devices to a normal operating condition. If this is not done, a second cable fault will
result in devices being lost from the addressable circuit. Always wait at least 3 minutes
between stopping a loop and reinitialising it.
