The function of emergency alarm systems is to 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:
• Personnel start ignoring the alarm messages.
• 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.
Coordinated lightning and surge protection prevents false alarms 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 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.
Boiler selection for optimal thermal energy performance
Electrical Power & Protection
The changing world of boilers means companies wishing to improve their thermal energy efficiencies while containing costs and environmental impacts must make careful and informed decisions. AES’s rich pool of experience, ability to keep pace with new steam trends and technologies, and understanding of their clients’ production processes can assist clients to weigh up different options in a careful and informed manner.
Read more...Securing Africa’s energy future starts at home ACTOM Electrical Machines
Electrical Power & Protection
Africa’s energy demands are surging, but the current reliance on imported solar technology leaves the continent vulnerable. This is why the prospect of building inverters and lithium batteries locally, designed for South Africa’s specific needs, is so promising.
Read more...Dry-type transformers for Dutch intake substation
Electrical Power & Protection
A data centre in the Netherlands is the site of a recent innovation on the transformer landscape, where TMC Transformers has designed, manufactured and installed dry-type transformers in a large intake substation.
Read more...Generators: The muscle in the new energy mix WEG Africa
Electrical Power & Protection
Contrary to their reputation as noisy and dirty, generators are a key part of modern energy supplies. Generators are reliable electricity workhorses in times of need. But they are also becoming welcome additions to modern energy mixes through efficiency improvements, noise reduction and flexible design choices.
Read more...Condition-based maintenance can revolutionise business continuity Schneider Electric South Africa
Electrical Power & Protection
As businesses experience growing pressure to enhance operational efficiency and reduce downtime due to electrical failure, condition-based maintenance becomes essential for preventing unforeseen equipment breakdowns by assessing the real-time health of electrical systems.
Read more...Ball valves and actuators to optimise HVAC performance Schneider Electric South Africa
Electrical Power & Protection
Schneider Electric South Africa offers the full range of innovative SpaceLogic and EasyLogic ball valves and actuators. These cutting-edge products are designed to optimise HVAC system performance, ensuring comfort and energy efficiency in industrial, commercial and residential buildings.
Read more...Power over Internet splitter for reliable power distribution Vepac Electronics
Electrical Power & Protection
A manufacturing facility requires a stable power supply for its wireless access points mounted across the factory floor. However, these devices do not support direct PoE input. By deploying the IPS-342P PoE Splitter from Vepac, the facility can efficiently convert PoE power from the network switch into 24 V DC output.
Read more...World’s fastest 16-bit arbitrary waveform generator Vepac Electronics
Electrical Power & Protection
The ARB Rider AWG-5000 is the world’s fastest 16 bit Arbitrary Waveform Generator, with 6,16 GS/s real time update rate (12,32 GS/s in RF mode) and 16 bit vertical resolution.
Read more...Wireless test tools Comtest
Electrical Power & Protection
Fluke has on offer the Fluke 376 FC True-RMS Clamp Meter with iFlex, the most advanced troubleshooting tool for industrial and commercial electricians
printer friendly version