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End Of Line detection board
The End Of Line (EOL) detection board makes a continuous check of the integrity of the
loudspeaker line based on a pilot tone. This check is in addition to the check given by the
impedance measurement. The pilot tone is independent of the quantity of the loudspeakers in
the system or the load on the speaker cables.
The EOL is installed in the speaker cabinet at the furthest point on a loudspeaker line. When
the EOL detects a pilot tone that is given by the voice alarm system, the loudspeaker lines
have no fault. The EOL trigger output is closed and the LED lights up to show that the lines
have a pilot tone signal.
If the loudspeaker cable has a fault, the pilot tone stops. The EOL circuit becomes open,
which is detected by the Voice Alarm Controller.
One EOL board can be installed to give a single fault indication per zone or more than one can
be installed on a single fault input to check the integrity of a loudspeaker line with several
branches. When more than one EOL board is installed, the configuration is called a daisy-
chain.
When a fault is detected by the Voice Alarm Controller, to find the EOL board that detects the
failure, every individual board must be checked.
Application examples
Schools
Schools are typical example of applications with a large number of zones each with a relatively
low output power requirement per zone. The main priorities are speech intelligibility and
compliance with IEC 60849 standard (or equivalent). In addition to mandatory voice alarm
functionality for evacuating staff and students, EVAC systems for schools should also include
chime tones for notifying the start/finish of lessons, plus public address functionality for
individually calling classrooms or public area. BGM is not essential. Since a classroom has a
low ambient noise level, 1 loudspeaker is usually sufficient, keeping the total power
requirement relatively low. Outside areas such as playgrounds and sports fields will require
weatherproof horn loudspeakers.
Summary of requirements
–
Typically 20 to 60 zones (in high schools)
– Speech intelligibility is the main priority
– Low power requirement (1 loudspeaker) per classroom
– Fireman’s panel by main entrance
– Call station in main office
– Additional public address functions such as chime tones desirable
– BGM in recreation areas is optional
Solution for a 30-zone system
The Plena Voice Alarm System Controller handles message routing to 6 zones, the remaining
24 zones require four additional 6-zone routers. The office is equipped with a call station plus
keypads for individually addressing zones, while a fireman’s panel (with overall priority) is
built in by the main entrance.
Power requirements
The system controller features a built‑in 240 W power amplifier, making it possible to drive up
to 40 loudspeakers with a power handling capacity of 6 W each. This is sufficient for a
medium-sized high school with 24 classrooms, 4 toilets/changing rooms, a staff meeting room
3.11
3.12
3.12.1
32 en | System overview Plena
2013.07 | V2.0 | Installation and Operation manual Bosch Security Systems B.V.