Careful Networking

The networking of technical safety systems with one another and with building technology delivers numerous advantages above all in large buildings and industrial complexes. However, it also brings with it significant risks. Until uniformly applicable standards and regulations exist, planners and installers should implement networked solutions with the greatest of care.

FeuerTRUTZ International 2017-01: Careful Networking
Fig. 1: Even large industrial halls can be comfortably ventilated in an energy-saving manner using a bus-based natural smoke and heat extraction system. (Source: Lance Anderson on Unsplash)

By Christian Kühn. One of the numerous advantages offered by the networking of technical safety systems is that the information received from sensors in individual systems can be utilised by other groups throughout the building. This makes visualisations, central control and monitoring, as well as (partial) automation solutions and multidisciplinary application scenarios, possible as a result. Users benefit overall from improved functionality, greater energy efficiency and lower costs. For example, fire detectors can pass on their information about room temperatures and air quality to a building management system. A smoke and heat extraction system (SHE) can be utilised in normal operation for energy efficient ventilation. The cost effectiveness of these systems also increases, e.g. by remotely carrying out initial fault analyses, by allowing commissioning and servicing calls to be handled more efficiently.

Safety first

FeuerTRUTZ International 2017-01: Careful Networking
Fig. 2: Remote access makes the control panel for a fire detection system accessible from a faraway location even on a tablet. (Source: Schlentzek & Kühn)

Yet networking also brings additional risks. This is particularly true in the case of safety systems designed to protect life and limb e.g. hazard detection systems (HDS). It is vital that their safety-relevant functions are not negatively impacted under any circumstances (freedom from interference). Therefore, a network – where possible with remote access – must take data protection aspects such as protection against sabotage e.g. by cyber attacks or computer viruses just as much into account. However, the risk of interference with core safety-relevant functions of networked system also grows as the number of interfaces and possibilities for remote access rises.

Networked safety systems have already existed for some time; extinguishing systems are already controlled e.g. by fire detection systems and danger management systems are linked into building management systems. However, the interfaces and transfer protocols are strictly managed by standards and/or regulations to guarantee freedom from interference. The functionalities and data volumes are generally severely restricted and only intended for a very narrow range of applications.

The article was published in FeuerTRUTZ International, issue 1.2017 (January 2017).
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Requirements are increasing

However, programmable intelligent safety systems, which exchange bidirectional data with a variety of network components via standardised interfaces, are required to achieve interdisciplinary networks that deliver added value and enable flexible scenarios. The large volumes of data and the number of components requires the digital transfer of standardised data packets. In existing approaches, protocols and buses from building automation, such as EIB/KNX, or from industrial automation, such as CAN-Bus, LON or Bacnet, have been utilised because standardisation and networking have already been promoted in these fields for a long time.

However, the protocols or buses from the field of building automation in particular often lack safety functions such as incident prioritisation, fault recognition or authentications because they were not developed for use in safety-relevant environments.

Are IP networks the silver bullet?

IP networks, where the systems are networked using the highly standardised TCP/IP protocol via Ethernet, are in ever greater demand. This solution places almost no limits on the diversity and quantity of the transmitted data. Many standardized products from the area of data technology can be economically integrated, including sharing data-based IP networks. However, there are currently limits to its use in the field of safety technology because there is a lack of, amongst other things, applicable standards and guidelines that could guarantee a sufficient level of safety and security for these networks.

A pioneer in this field is video technology due to the sharp increase in data volume of higher resolutions that must be transmitted in accordance with the DIN EN 62676 [1] standard for secure IP video transmission.

In addition, numerous other standards and guidelines on the subject of networking that focus on individual trades or certain functionalities exist that have been developed by a variety of different rule-making bodies.

Uniformly applicable rules for all trades and standardised interfaces or transmission channels are not currently on the horizon in Europe.

Nevertheless, it is already possible to achieve significant added value by networking technical safety systems, as the two examples below demonstrate. The prerequisite is that planners and installers also have specialist expertise in the field of data processing, so that sufficient safety and security is guaranteed alongside all of the added benefits.

Ventilation of industrial halls

It is possible to achieve energy efficient and comfortable ventilation control during normal operation with natural smoke and heat extraction systems (NSHE). Depending on the weather, temperature and other influencing factors, the smoke and heat extraction openings can be controlled during normal operation to ensure ideal ventilation at all times.

However, conventional SHE systems reach their limit above all in sophisticated industrial halls. On the one hand, they do not allow for the programming of complex scenarios in which numerous motor-driven windows need to be individually controlled. On the other hand, the length of the cables for conventional SHE systems increases sharply as the size of the building increases because motor and control cables must be more or less individually routed to the SHE control unit.

Bus-based systems, which have been available on the market for some time, do not suffer from these disadvantages; systems based on the LON or CAN-bus are available. The cabling costs are drastically reduced here because the cables to the motors and control elements are laid decentrally via bus nodes to the SHE control unit. Each bus device can be addressed individually via a unique address so that even complex programming is possible. This means that e.g. individual fully automated night cooling is more economically feasible compared to mechanical ventilation.

Remote inspection of fire detection systems

FeuerTRUTZ International 2017-01: Careful Networking
Fig. 3: Messages from the alarm system are also immediately sent to the mobile device of the service technician. (Source: Schlentzek & Kühn)

Remote access to fire detection systems enables economic operation. Amongst other things, commissioning and servicing calls can be handled more efficiently and higher levels of availability can be achieved. The specific details are regulated by DIN VDE 0833-1 [2]. According to this application standard, various types of access are permitted under certain circumstances, from accessing status reports and management tasks (switching off detection lines) through to loading updates and reprogramming remotely. Yet if there is an error, the risk of system malfunction right through to total failure increases, which could have fatal consequences if there are no service personnel available on-site [3].

It is currently advisable for safety reasons to access these systems in read-only mode e.g. when maintaining fire detection systems equipped with remote access. Software changes (including updates) or interventions into the detection structures should generally only be carried out on-site so that any errors made by the service technician can be quickly resolved – if necessary with remote support. The tests required during a service or following a repair can also be effectively supported with the aid of a mobile application. This strategy makes it possible to significantly optimise the organisation of service provision – without compromising on safety.

Summary

Networking safety systems with one another and with building technology systems gives planners and installers great opportunities to offer their customers economical and intelligent applications that deliver a high level of added value. Yet in the absence of standardised interfaces and transmission protocols, planners and installers should however take great care when realising networked safety solutions for their customers. The reliable functionality of the technical safety systems must always be the priority. Great expertise is demanded of those involved in the construction of these networks because not all of the systems on offer meet with this requirement.

Author

Christian Kühn: Managing Director of the specialist installers of safety systems Schlentzek & Kühn based in Berlin; Chairman of the ZVEI Installers’ and Planners’ Consortium – Zentralverband Elektrotechnik- und Elektronikindustrie e.V.

Literature

[1] Standard DIN EN 62676; VDE 0830-7-5: “Video surveillance systems for use in security applications”

[2] DIN VDE 0833-1; VDE 0833-1:2014-10: “Alarm systems for fire, intrusion and hold-up – Part 1: General requirements”

[3] ZVEI Information Leaflet 33010:2014-02 “ZVEI Merkblatt für die Interaktion mobiler Endgeräte mit Brandmelderzentralen über IP-Netze” (ZVEI information leaflet for interaction between mobile end devices and fire detection centres via IP networks), free download from www.zvei.org/Publikationen/Integration-mobiler-Endgeraete-mit-Brandmelderzentralen-ueber-IP-Netze.pdf

The article was published in FeuerTRUTZ International, issue 1.2017 (January 2017).
More information about eMagazine FeuerTRUTZ International

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