Preventing false alarms caused by lightning strikes and surges
This article has been supplied as a media statement and is not written by Creamer Media. It may be available only for a limited time on this website.
Company Announcement - The function of emergency alarm systems, albeit fire or burglar, is to actively produce an alarm in the event of danger and to remain passive when there is none. The malfunction of these systems, either no alarm sounding if there is danger or an alarm sounding unnecessarily, is not just a nuisance; it can also be dangerous and can result in expensive call-out fees.
False alarms have the following consequences:
• Security personnel start ignoring the alarm messages.
• Neighbours are disturbed by acoustic alarms.
• Emergency staff is unnecessarily called out.
• The triggering of fire extinguishing systems can cause interruption of operations.
All these factors cause unnecessary costs and can be prevented if possible causes of false alarms are recognised at an early design stage and are eliminated by taking suitable preventive measures. Lightning strikes are one such cause, and given the profusion of summer storms in South Africa, this is a real threat. And with many businesses closing over the December holiday, ask yourself: do you want to be called back if your property experiences a false alarm? Coordinated lightning and surge protection prevents false alarms or the destruction by atmospheric discharges or switching over voltages and increases the availability of the systems. Many of today’s emergency alarm systems have an increased immunity to transients on the primary lines, secondary lines and mains voltage cables according to IEC 61000-4-5. Nevertheless, only external and internal lightning protection measures provide comprehensive protection against damage resulting from lightning strikes and surges.
Monitoring principles
Different monitoring principles are used for emergency alarm systems:
• Pulse polling technology: Information from the sensor which has triggered the alarm is digitally transmitted. This allows the identification of the sensor and its exact location.
• DC circuit technology: According to the closed circuit principle, every alarm line is permanently monitored. If a sensor in a line is triggered, the line is interrupted and an alarm is produced in the alarm panel. However, only the alarm line, but not the individual sensor can be identified.
Irrespective of the monitoring principle used, all cables extending between the different areas of the emergency alarm system must be integrated in the lightning and surge protection concept of the overall system.
Recommended protection
DEHN’s BLITZDUCTOR XT, type BXT ML2 BE, must be installed to protect two-wire alarm lines and connect the earth drain wire by means of an EMC spring terminal. For cables with more than two wires, a four-wire version, BXT ML4 BE, is available. Surge protective devices are selected according to the voltage of the alarm lines, which is typically between 12 and 48 V. The low internal resistance is also a clear advantage of BLITZDUCTOR arresters since the maximum resistances of the alarm lines must not be exceeded. For the outputs of the alarm panels (acoustic and visual) it must be ensured that the nominal current of the surge protective devices is not exceeded.
The market leader DEHN, a globally active family-owned electrotechnical company with more than 1600 employees worldwide, offers innovative products and solutions as well as comprehensive services in the field of surge protection, lightning protection and safety equipment. DEHN focuses on the protection of system and building technology, the transportation, telecommunication and process sector, photovoltaic systems, wind turbines, etc. The company's continuous growth is based on more than 100 years of tradition and experience as well as highest quality standards and consistent customer and market orientation throughout the world.
Comments
Announcements
What's On
Subscribe to improve your user experience...
Option 1 (equivalent of R125 a month):
Receive a weekly copy of Creamer Media's Engineering News & Mining Weekly magazine
(print copy for those in South Africa and e-magazine for those outside of South Africa)
Receive daily email newsletters
Access to full search results
Access archive of magazine back copies
Access to Projects in Progress
Access to ONE Research Report of your choice in PDF format
Option 2 (equivalent of R375 a month):
All benefits from Option 1
PLUS
Access to Creamer Media's Research Channel Africa for ALL Research Reports, in PDF format, on various industrial and mining sectors
including Electricity; Water; Energy Transition; Hydrogen; Roads, Rail and Ports; Coal; Gold; Platinum; Battery Metals; etc.
Already a subscriber?
Forgotten your password?
Receive weekly copy of Creamer Media's Engineering News & Mining Weekly magazine (print copy for those in South Africa and e-magazine for those outside of South Africa)
➕
Recieve daily email newsletters
➕
Access to full search results
➕
Access archive of magazine back copies
➕
Access to Projects in Progress
➕
Access to ONE Research Report of your choice in PDF format
RESEARCH CHANNEL AFRICA
R4500 (equivalent of R375 a month)
SUBSCRIBEAll benefits from Option 1
➕
Access to Creamer Media's Research Channel Africa for ALL Research Reports on various industrial and mining sectors, in PDF format, including on:
Electricity
➕
Water
➕
Energy Transition
➕
Hydrogen
➕
Roads, Rail and Ports
➕
Coal
➕
Gold
➕
Platinum
➕
Battery Metals
➕
etc.
Receive all benefits from Option 1 or Option 2 delivered to numerous people at your company
➕
Multiple User names and Passwords for simultaneous log-ins
➕
Intranet integration access to all in your organisation