O₂, Germany
Increase the availability using the protection concept

O₂ Germany, a subsidiary of mm O₂ plc, caters to all telecommunication requirements of its mobile phone customers.

With its own extensive network infrastructure, O₂ also offers mobile data services based on GPRS technology in addition to innovative postpaid and prepaid products. Moreover, O₂ will introduce the next UMTS (3G) mobile phone generation products in the market.

Application

O₂ Germany started its operations in eight conurbations after acquiring the license for the second GSM 1800 network (E2 network). Owing to technical reasons, radio cells used for the GSM 1800 system are smaller, require a higher radio cell density and thus a large number of base stations.

Around 9000 base stations (BTS) were set up over the last few years. Setup in open spaces is a prerequisite for a good wireless connection.

Base stations must be protected due to the high risk of lightning strikes. Cost-intensive technology and the desire for continuous availability of the network make a protection concept absolutely essential.

Protecting base stations from the high risk of lightning strikes

Solution

Surge protection components for maintaining the power supply

Mobile phone base stations are normally located on buildings. For such installations, surge protection devices are used directly upstream to a base station and in the counter section in order to ensure the supply.

A base station, which is called node B in a UMTS network (3rd Generation), includes a transmission and receiver system, an antenna system and their electric power supply.

When selecting surge protection components, special importance is given to maintaining the power supply and the constant availability of a base station.

Since the start of the GSM 1800 network from O₂ Germany, power supply units of the mobile phone systems have been reliably protected against surge voltage through combinations of FLASHTRAB lightning arresters and VALVETRAB surge arresters. Items located in the counter area have sufficient insulation strength and hence FLASHTRAB lightning arresters offer adequate protection.

O₂ base stations are equipped with arresters that work as per the AEC (Active Energy Control) principle developed by Phoenix Contact. AEC stands for Active Energy Control between the lightning and surge arresters. The operating voltage of the FLASHTRAB FLT 35 CTRL-0.9 lightning arrester used is 900 V and has been preset using trigger electronics.

Lightning and surge arresters can thus be directly connected in parallel. A B/C arrester combination, which meets the requirements of all lightning protection levels for a maximum design width of 140 mm (3+1 connections in TN/TT systems), has been implemented in combination with the VALVETRABVAL-MS 230 surge arrester.

In close collaboration, we have developed a protection concept corresponding to the technical specifications given by O₂. Additional support also includes suggestions for an EMC-compatible set-up of the electrical subdistributions used within the area of the base stations as well as selecting arresters that meet the requirements for intended use. An electrical subdistribution set up in accordance with these suggestions was tested in the in-house lightning current test laboratory.

Summary

The appropriate selection of surge protection devices increases the availability of the entire radio/transmitter-receiver system and ensures the quality of services available.

Using arresters based on the AEC principle allows a compact EUV that protects the power supply unit of a mobile phone base station against lightning surge voltages efficiently and cost-effectively.