The Control Unit

THE CONTROL UNIT 

This is the heart and local brain of the system. It receives the first notification that an alarm condition has occurred and then decides what action has to be taken. With simpler panels this usually means activating the warning devices. With microprocessor type panels this action could be considerably more complex such as interrogating the detection device to verify the condition, recording events in the memory or ignoring the device until it activates again.

Control panels display conditions by means of lights or LED’s flight emitting diodes) on the front of the panel e.g., clear, fault, mains on, etc. For more sophisticated panels this is sometimes effected by means of an alphanumeric display. A series of words and numbers will be produced on a screen such as, zone one open, tamper zone three, etc.

A key switch or keypad is provided to switch the system on or off. Again with more complex panels the keypad can be used to perform functions like interrogating the memory, inhibiting a zone, testing the warning devices and programming the system to react in the required manner to different situations.

THE ABOVE SHOWS A DIAGRAM OF A BASIC CONTROL PANEL

POWER SUPPLIES

Power for the alarm system is derived from the 240V AC mains supply. It is converted to 12V DC by the power supply unit and it is this voltage that is used for the System should a mains failure occur then standby batteries, housed inside/the control panel, will take over and power the system. When mains returns these batteries will automatically recharge.