Fire detection and protection through safety critical systems

Jon Lawson

Stephen Pratt explains how safety-critical systems in the power engineering industry are getting ‘smart’ when it comes to fire detection and protection

The Internet of Things (IoT) is a network of physical devices, vehicles, home appliances and other items embedded with electronics, software, sensors, actuators and connectivity that enables these objects to connect and exchange data. Each ‘smart’ thing is uniquely identifiable through its embedded computing system but can inter-operate within the existing internet infrastructure, transmit data to the cloud for processing and be managed and controlled via applications.  

Safety systems expert Blaze has harnessed the digital technology of these smart devices to connect and ‘talk’ to fire detection and protection systems on remote or unmanned installations and sites such as offshore windfarm platforms or solar energy plants. Digitalisation can also offer the opportunity to increase safety and lower costs by providing specific visibility of the status of connected equipment. Blaze has recently completed projects for Orsted and Engie using this technology.

More than one million devices are currently connected to cloud-based IoT platforms and this figure is expected to reach 1.25 million by the end of 2018. Cloud data is saved more securely than on many corporate computers, with IoT platforms aligning to the international IEC 62443 cyber security standard, which specifies the IT security levels of automated systems.

Much of the equipment that is used in fire protection and detection in the power sector is approved to national and international standards, but in many cases cannot be easily connected to provide visibility of systems, detectors and control panels. Experts such as Blaze work with equipment that provides connectivity and visibility, allowing the assembly of components and exchange of data and information that is unique to each site.  

Right tools for the job
The selection of these components and the way that they interact with each other is defined and engineered to ensure compliance with required standards and regulations, whilst providing the equipment required to enable connectivity and visibility. The software is programmed using the software tools provided by the equipment manufacturers, but the application software will be developed by Blaze and will be unique to the site.

Depending on the specific client requirements for detection, the company can provide standard EN54-compliant approved fire panels or enhanced SIL2 certified fire alarm panels, approved for offshore and onshore environments. The fire alarm equipment used will be predominantly addressable and employ analogue or digital addressable technology. As part of ensuring compliance with EN54, it is important that the most suitable uninterrupted power supply (UPS) is sized for the project. The company’s engineers will size the most appropriate batteries and UPS based on the required Amp/hr rating. The firm also uses an intelligent UPS system that allows key monitoring parameters to be passed to the programmable logic controller (PLC) via ethernet protocols. This allows key information to be distributed amongst local and third-party or operator interfaces in addition to the information being available for visibility remotely.

For the protection systems, clean agent gas suppression systems or foam water mist systems are usually specified. These systems can be operated and controlled by using local extinguishing control panels or can be tied back to a centrally located PLC, programmed to perform logic based on a project specific cause and effect document and in accordance with national or international standards. In both cases the architecture will be configured so that the extinguishing systems communicate with the addressable fire alarm system to make their status visible remotely.

The fire alarm panels are capable of operating on their own as single stand-alone units or can operate as networked units as may be necessary in the case of larger sites. The panels will be programmed using the manufacturer’s software to create the application for the client site, using cause and effect diagrams that can be supplied by the client or by Blaze.

To provide a step towards the system being connected, the company uses the Commander – a powerful internet protocol (IP) based controller that provides protocol translation, enabling the addressable fire alarm panel to be integrated to a powerful PLC. The Commander is used as a simple bridge between the addressable panel and the PLC allowing conversion from one protocol type to another. IP connectivity allows the Commander to be located locally to the distributed network panels, but at the same time caters for remote programming and remote third-party system access.

The PLC takes data from the Commander and performs actions based on what the received signals are, for example, displaying icons on the touchscreen for alarms. Similarly, actions are performed within the PLC based on communication with the touchscreen Human Machine Interface (HMI). The PLC systems used here are based on fail-safe SIL2 architecture to comply with the requirements of IEC61508. The company has in-house TUV functional safety certified engineers who will ensure that systems are verified and validated prior to release of the software to site. The SIL2 fail-safe CPUs have safety functions built in to the software and hardware to ensure that monitoring and proof testing of outputs can be easily activated and reported.

The alarm and diagnostic functions of the application program are used to alert the operators within the internal and external HMI and third-party systems. Local HMI applications provide control, visualisation, alarm annunciation and diagnostic of the PLC and fire alarm systems.

For any control functionality good engineering practices will always be used to prevent inadvertent single-click activation of control. This can be an issue with touchscreen HMIs with the screen saver activated. Therefore, all control actions are implemented with selection and confirmation prompts to validate the actions to the PLC system, with confirmation prompt designed to be in a different area on the screen than the initial selection to ensure the operator confirms the action.

For interaction with other equipment, the PLC is capable of communications with third party systems with a variety of protocols allowing integration to provide a simple, single operator interface.

The bigger picture
With careful and considered selection of the right components and implementation of the system, digitalisation of safety systems is possible, providing an effective solution to protecting remote or unmanned assets, reducing costs to the client and improving safety and efficiency of the asset.

Stephen Pratt is safety critical systems manager at Blaze Manufacturing Solutions


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