Reliable signal transmission in confined spaces

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High safety for persons and the environment – ensured by a comprehensive surge protection with minimal space requirements

The needs of system operators in the water and wastewater industry have changed drastically – there is a trend for higher packing density in the control cabinet and consequently ever narrower components. It is a characteristic of the water and wastewater treatment industry to have numerous networked processes – between field level, management level, and subsections that are usually far apart. The requirements on planners, installers, and operators of the systems are increasing steadily. Failsafe concepts are becoming more important due to the increasing implementation of electromechanical and electronic components, systems and solutions, as well as the networking between them.

Megatrends in the market

Overvoltage concepts play an important role.

Convenient connection: Conductors can be connected quickly with push-in technology and removed without any special tools

Further requirements on critical infrastructure have also developed due to the IT security law passed after concerns by the Federal Office for Security in Information Technology. Two major factors are at play here: high system availability and the resulting security of supply for the population.


As in other infrastructure fields, the trend towards implementing ever smaller and more compact components is also quite noticeable in the field of water and wastewater treatment. To optimize the costs of overall control cabinet manufacturing, the surge protective devices should take up as little space as possible. The goal is to centralize numerous service functions – such as system monitoring – in the control room. To operate the system safely from an EMC perspective, surge protective devices are implemented in large systems.

Protection in a confined space

572 signals per meter: With its extremely narrow components, Termitrab complete saves a lot of space in the control cabinet

Numerous channels often have to be housed within a small area in order to transmit analog or digital signals. Since space is becoming increasingly valuable, Phoenix Contact is launching the new Termitrab complete product range at the Hannover Messe 2017. The narrowest components of this product range have a width of only 3.5 mm. The components of Termitrab complete are equipped with six terminal points to which two signal lines each and a common reference potential can be connected. With this extremely compact and narrow contactor, which is being made available on the world market for the first time, up to 572 signal lines can be protected on one meter of DIN rail. The power dissipation has been minimized significantly as well, due to the decoupling resistors in the protective circuits. This feature also aims to satisfy the demand for installing more devices in increasingly smaller spaces.

Integrated status indicator: Thanks to the surge protection components of Termitrab complete, the user is kept up-to-date regarding the state of their system at all times

The lightning protection standards recommend regular inspection of protective devices. This is only possible through visual examination. The Termitrab complete product range presented here features a status indicator that displays an overload of the surge protection directly on the device. Since no additional power is needed for this indicator, the protective device also displays the fault continuously during an overload. If this information is displayed in a control room, the optionally available “remote signaling modules” ensure the necessary data transmission. Either the PLC (programmable logic controller) can query the potential-free contact directly by wire, or this contact is integrated by interface modules, with, for example, the compact message system TC Mobile I/O X200 from Phoenix Contact. This means that the status of the protective devices in large systems can be monitored not only in the control room, but also sent via SMS to the cell phone of the service technician. If a contactor is overloaded, trouble-free replacement is possible, in particular with the pluggable protective devices.

Permanent installation with push-in technology

Classical screw connection technology is still commonly used. If there are extremely many signal lines to be installed however, considerable time can be saved with the quick push-in connection technology. Comparisons with screw connection technology have shown, for example, that the wires can be connected up to 50 percent quicker. Disconnection is also easily possible by pressing the “pusher”. Depending on his preference, the installer can choose between screw and push-in connection technology with the Termitrab complete product range.

Convenient connection: Conductors can be connected quickly with push-in technology and removed without any special tools

Use also in explosion-protected areas

A lightning and surge protection concept is essential because of the higher risk in potentially explosive structural systems, often with far-reaching consequences for persons and the environment. In general, observation of lightning protection standard DIN EN 62305 [1], applicable for nearly all structural systems, is sufficient. Part 2 of the standard describes risk management for structural systems, which takes into account the effects of lightning strikes. The standard relates to all structural systems – even systems with explosion risk in accordance with DIN EN 60079-0 [2]. The “intrinsic safety Ex-i” type of protection is useful as a secondary protection measure in this environment. This type of protection limits voltages and currents so that a potentially explosive mixture of ignition energy and temperature is not reached. DIN EN 60079-11 [3] is the specific standard for these intrinsically safe circuits – here too, reference is made to the necessity of lightning and surge protection.

For all systems that require high availability, a failure lasting for even a short time is unacceptable. That is why the requirements for surge protection are also more stringent for such systems. The surge protection of the Termitrab complete TTC-Ex product range was designed for such systems. The Ex-i certification of the TTC-Ex components permits the use in field distributors for Ex-zones 1 or 2. Additional approvals attest to the suitability in accordance with Fisco (fieldbus intrinsically safe concept).


In water and wastewater treatment, there is an increased failure risk in large systems due to surge voltages, often with far-reaching consequences for persons and the environment. A comprehensive and well-planned lightning and surge protection concept is therefore crucial. Using surge protection with telecommunicating status indication ensures quick detection in the control room. Due to the compact design – with only 3.5 mm width for the narrowest components – the space needed for MCR surge protection can be reduced significantly. Use in explosion-protected areas is also trouble-free with the available approvals. Thanks to the comprehensive product range, there is a suitable solution for every application in water and wastewater technology.

– Dipl.-Ing. Ralf Hausmann, Product Marketing, Surge Protection Trabtech, Phoenix Contact GmbH & Co. KG, Blomberg

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