Surge protection for telecommunication systems

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Telecommunications system in front of a cityscape

Increased availability

An important measure to increase availability is to guarantee the energy supply. Power supply failure caused by transient events can be effectively avoided through the consistent use of lightning and surge protective devices. Therefore, surge protection is now mandatory in many countries.

Especially when it comes to critical infrastructures, such as telecommunications technology, it is absolutely vital that lightning and surge protection is used to increase availability. However, lightning and surge protection must also be taken into consideration for all types of residential and functional buildings in private, commercial, or industrial environments.

Surge protection of telecommunications systems

A wide range of information from different network elements and locations is processed in a data center. This includes data from the cellular stations, but also all information from the fixed-line network nodes, which in addition to voice communication also ensure data communication. A failure in a data center of a telecommunications provider can have far-reaching consequences. A large number of customers will always be affected in the event of any failure.

What are the challenges for Telefónica?

5G, the new generation of cellular communication, will give rise to entirely new applications in the fields of IoT and digitalization. We are already seeing very specific applications taking shape in the field of networked driving as well as in industry. This demands a lot from our communication networks, but above all requires a high level of reliability.

Oliver Tananow - Telefónica Germany GmbH & Co. OHG, Senior Specialist Electrical Engineering Core Site
Oliver Tananow, Senior Specialist Electrical Engineering Core Site, Telefónica Germany GmbH & Co. OHG

Oliver Tananow, Senior Specialist Electrical Engineering Core Site, Telefónica Germany GmbH & Co. OHG

Along with the redundant structure used for the power supply, appropriate lightning and surge protection measures are also implemented at all relevant units along the power supply route. This helps to overcome the challenge mentioned above and secures availability in the operation of cellular communication and fixed-line networks.

We will look at sensitive locations that benefit from the installation of lightning and surge protective devices in more detail below.

Feed-in with installed surge protection and busbars

SPD in the feed-in and monitoring with ImpulseCheck

Feed-in

A type 1+2 combined lightning current and surge arrester provides the necessary protection here at the energy provider’s delivery point into the data center. The discharge capacity of this device class can even safely handle lightning currents up to 100 kA and discharge them to ground. It is essential that feed-in is protected, which is why the surge protective device (SPD) is additionally monitored with ImpulseCheck. The ImpulseCheck assistance system for surge protection detects any pre-existing damage to the SPDs and reports the condition of the protective devices to the control room.

Main distribution with type 1+2 special combined lightning current and surge arrester plus monitoring

Main distribution in the data center: protection against lightning and overvoltages with type 1+2 special combined lightning current and surge arrester

Main distribution

The cables from the feed-in and the emergency power supply come together in the main distribution. As high lightning currents and overvoltages can also be expected in this part of the system, a compact device combination (type 1+2 special combined lightning current and surge arrester) provides lightning and surge protection. ImpulseCheck is also used for condition monitoring of the SPD at this sensitive point in the supply.

Control cabinet with terminal blocks and installed SPD

Type 1+2 combined lightning current and surge arrester to protect the emergency power supply against overvoltages

Emergency power supply

If, contrary to expectations, the main power supply suffers a failure, the emergency power supply kicks in. A large battery storage system bridges the time until the permanently installed diesel generator is ready for use. This happens fully automatically. This redundant power supply is of course also protected against overvoltages.

In this particular application scenario, although lightning current cannot be directly coupled into the system sections of the generator, partial lightning currents are likely to occur in this area. Switching from normal operation to emergency power operation also carries the risk of surge voltage couplings. In order to minimize this risk, a type 1+2 SPD is used.

Light-flooded room with several server cabinets

The heart of every data center – the server room

Server room

The most important room in every data center is the server room. In the event of a server failure, the remote signaling network will also fail. As both cellular and fixed-line network communication is handled via the servers installed here, it is absolutely essential that they are protected against overvoltages.

The servers are typically operated with 48 V DC voltage. The supply lines into the server rooms are protected with type 2 surge protection intended for DC applications.

Large climate chambers for cooling the server rooms

The air conditioning is one of the sensitive areas in a data center

Air conditioning

Another important component in the data center is the air conditioning. The temperature in the server rooms can increase considerably if the air conditioning suffers a failure. This would result in the servers shutting down or, at worst, some server racks could suffer a failure due to overheating. Here, type 2 surge protection prevents failures caused by overvoltages. The type 2 protective devices discharge overvoltages up to a maximum discharge surge current of 40 kA. The surge protective devices have a maximum voltage protection level of 1.5 kV. Depending on the design of the power supply for climate control, products for one to three phases are used.

Summary

Critical infrastructure generally refers to assets or systems that play a vital role in ensuring that economic, social, or business functions are performed and maintained. The failure or malfunction of such a function has a significant impact on the well being of the population.
The examples illustrated here are based on the protection of a data center operated by Telefónica Deutschland. To ensure the availability of the services offered in cellular communication and fixed-line networks, the chosen example also shows that many different installations need to be taken into consideration.