Understanding Alarm Systems: Types, Objectives, and Components

Understanding Alarm Systems

Types of Alarms

• Anti-Theft (Anti-Intrusion):
  • Housing
  • Establishments
• Security: Prisons, nuclear power plants, etc.
• Environmental: Fire, water leakage, gas, etc.
• Technical Alarms
• Medical Alarms
• Access Control Systems
• Monitoring in Industrial Processes

Objectives of Alarm Systems

• Familiarize users with the operation of various detectors.
• Describe the components of an alarm system.
• Enable installation and operational checks of alarm systems.

Anti-Intrusion Systems

• Passive System: Fences, security doors, etc.
• Active System: Detects threats using electronic controls.
• Deterrent System: Visible measures indicating robust protection.

Alarm System Components

A) Detector Elements

These send an electrical signal to the control unit by opening or closing a circuit, or through a transducer that converts a physical quantity (chemistry, etc.) into an electrical signal.

B) Central Processing Unit

This receives electrical signals from the detectors, identifies the area where the anomaly occurred, and generates the alarm signal. It also sends commands to activate controls to correct the defect, such as opening or closing a valve, or activating a fan.

C) Signaling Devices

These receive the signal from the central processing unit and generate audible and/or visual warnings. Through a telephone dialer, a message can be sent to a central receiving station (CRA), fire department, central monitoring, etc.

D) Connection Elements

These are responsible for establishing electrical contact between the various components of the alarm system (sensors, central signaling elements). They vary depending on the application, ranging from simple parallel cables to shielded coaxial cables.

Types of Detectors by Placement

Detectors can be classified into large groups based on their placement:

• Peripheral
• Volumetric
• Perimeter

Peripheral Detectors

These monitor the interior air without needing to open doors, windows, or walls.

• Magnetic Opening Detectors
• Shock Detectors
• Seismic-Electronic Detectors
• Glass Breakage Detectors
• Thermal Detectors
• Etc.

Volumetric Detectors

These monitor the air inside a transparent space without needing to open any door or window.

• Microwave (MOV)
• Ultrasound (20 or 40 kHz)
• Infrared
• Microphone (20 to 20,000 Hz)
• Infrasound (below 20 Hz)
• Etc.

Perimeter Detectors

These are generally placed outside in an enclosed perimeter and provide early detection before an intruder reaches the building.

Being located in exposed environments, they must withstand weather impacts (fog, light, water, wind, snow, etc.) and have systems to mitigate false alarms due to these conditions.

• Infrared Barrier
• VHF Barrier
• Television Cameras
• Seismic Sensors
• Electric Field Sensor (for Broadband RF) (1 MHz to 16Hz)