RDM0001/3_2 Page 18 of 70 © 2015 - 2017 Protec Fire Detection plc
10.0 Coincidence/Dependency Operation
At the time of commissioning, the system may have been programmed to operate in one of three
‘coincidence’ modes where a confirmation signal is required. The confirmation signal is normally the
same or a second device generating a fire signal.
Mode ‘C’ is the standard coincidence mode used in Protec fire alarm systems.
Coincidence operation is used to minimise the effects of false alarms by providing time to investigate
the first fire signal and if found to be an unwanted activation, prevent a full evacuation of the
premises and an unnecessary call to the fire brigade.
Mode ‘A’, also known as Dependency/Coincidence Type ‘A’ indicates the zone in alarm and sounds the
panel buzzer, however it does not light the general fire led and activate the outputs unless there is a
confirmation signal from the same device or an automatic device in the same zone.
Mode ‘B’, also known as Dependency/Coincidence Type ‘B’ indicates the zone in alarm and sounds the
panel buzzer, however it does not light the general fire led and activate the outputs unless there is a
confirmation signal from the same device or an automatic device in any zone.
Mode ‘C’, also known as Coincidence/Dependency Type ‘C’ indicates the fire alarm as normal but does
not activate any outputs until there is a confirmation signal from another device (manual or
automatic) in any zone or a programmed timeout expires.
In general, coincidence only applies to automatic detector activations whilst a manual
activation on a zone (Activating a Manual Call Point) overrides coincidence.
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