
Connection of signalling devices
Signalling devices are: self-powered sirens, indoor sirens, telephone dial-
lers, etc.
Signalling devices can be classified as follows:
Ø Intrinsic security devices activated by power failure on the specific termi-
nal e.g. self-powered sirens.
Ø Positive Alarm line devices activated by positive (12 V) on the terminal
e.g. indoor sirens.
Ø Negative Alarm line devices activated by ground on the specific terminal.
Ø Balanced Alarm line devices are activated by unbalanced impedance
on the specific terminal.
All types of signalling devices can be connected to the voltage free alarm-
relay contacts (terminals 19, 20, 21).
Figure 17 shows the connection of a self-powered siren, and an indoor si-
ren.
Figure 17 Connection of self-powered siren and indoor siren
INSTALLATION 27
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