Specifications

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EN54 FIREFINDER PLUS INSTALLATION,COMMISSIONING & OPERATION
4.13.1 Detector loop Isolator Installation
In applications where it is not necessary to use an isolating base for each detector, up to 20
detectors may be installed between isolating bases.
Note: Refer to Apollo Isolating specifications and guidelines for further details.
If a short circuit or abnormally low impedance occurs, the base isolates the negative supply in the
direction of the fault. When the short circuit is removed the power will automatically be restored.
Note: Isolating base is polarity sensitive.
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Figure 21: Typical Loop Arrangement
4.13.2 Loop Isolator calculator
The number of isolating devices on the loop can limit the maximum loop cable length depending on
the type of cable used and the total loop current. Refer to the tables below for reference.
4.13.3 Loop Open / Short Circuit.
In the case of an Open Circuit or Short circuit (short circuit isolators used) on the Loop Line the Loop
board provides the ability to drive out from both sides of the loop (In and Out). When these Faults
are repaired / cleared the panel will still report a Loop Fault until a Loop Test is performed on the
appropriate loop. See section 8.5