Basics of Security Alarm Systems (From Physical Security Readings From Security Management Magazine, P 91-102, 1986, Shari Mendelson Gallery, ed. - See NCJ-101017)

• NCJ Number: 101021
• Author(s): J C Shanahan
• Date Published: 1986
• Length: 13 pages
• Sale Source: Butterworth-Heinemann
• Language: English
• Country: United States of America
• Note: Reprinted from Security Management, August 1980.

Annotation

This article explains alarm components, the basic security circuit, circuit supervision, security sensors, alarm types, defense lines, and alarm codes and standards.

Abstract

Basic alarm components are sensors, a premises control unit, a system control unit, and alarm annunciators. The basic security circuit, connected to the system control unit, monitors an electrical current flowing through the circuit wiring, the sensor contacts, and an end-of-line device. If the current in the circuit drops or rises to predetermined values, the system control unit causes an alarm. Circuit supervision built into an alarm system signals when the system is not operating properly due to circuit faults or tampering. Current standards require supervisory techniques that trigger the alarm when current conditions are altered due to a circuit fault or tampering. Security sensors detect an alarm condition and generate a signal to the system control unit. Passive sensors respond to changes in the given environment, and active sensors detect changes in the environment they themselves create. Alarm systems vary according to the type of protection required and the manner in which alarm signals will be handled. Lines of defense for alarm systems are the facility perimeter, a specific area, and a particular object. The security alarm industry is guided by Underwriters Laboratories standards, which are used to test the equipment and set requirements for system operation and installation.