Bosch Security Systems | 2006-06 | 9922 141 10377 en
Plena Voice Alarm System | Installation and User Instructions | Introduction en | 15
3 Application examples
3.1 Schools
3.1.1 Introduction
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 IEC60849
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.
3.1.2 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
3.1.3 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.
3.1.4 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 and 2 offices, each requiring a single
loudspeaker. The canteen, assembly hall, playing fields
and corridors typically require more loudspeakers per
zone. An additional Plena Power Amplifier is used as a
spare amplifier.
3.1.5 Layout
See figure 3.1, table 3.1 and table 3.2.
table 3.1: Zones
Zone Description Power
Z1-22 Classrooms 22 x 6 W
Z23 Toilets/changing rooms 4 x 6 W
Z24 Staff meeting room 1 x 6 W
Z25-26 Offices 2 x 6 W
Z27 Corridors 4 x 6 W
Z28 Assembly hall 2 x 6 W
Z29 Lunch canteen 2 x 6 W
Z30 Playing fields 1 x 10 W
Total 232 W
table 3.2: Units
Unit Description No.
LBB1990/00 Controller 1 x
LBB1992/00 Router 4 x
LBB1996/00 Remote control 1x
LBB1997/00 Remote control extension 4x
LBB1956/00 Call station 1x
LBB1957/00 Call station keypad 4x
LBB1935/00 Power Amplifier (240 W) 1x
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