Fire detection systems of MVG underground stations

With its underground, tram and bus network, the Münchner Verkehrsgesellschaft (MVG) is the largest local transport company in the city of Munich.MVG's underground trains alone transport over a million people every day.

DEHN offers customised lightning and surge protection solutions for the fire detection systems to ensure reliable fire protection in the underground stations.

DEHN solution	Lightning and surge protection for underground stations
Customer	Stadtwerke München
Sector	Safety technology
Product	BLITZDUCTOR XT

The challenge

Fire alarm systems constitute safety equipment. Their tasks include locating fires at an early stage, triggering the alarm in the underground station and being able to send the alarm message to the fire brigade at any time. False alarms caused by interference voltages or transient overvoltages can have serious consequences.

Different operating voltages, such as the 750 V DC supply of the underground, 230/400 V AC in the electrical installations and 24 V AC/DC in safety technology (fire alarm system), can cause inadvertent interference voltages that often lead to considerable damage to the safety technology.

Likewise, different earthing systems can lead to large potential differences that have a negative impact on the operation of fire alarm systems.

protected.

The solution

The focus is always on the safe operation of the technology and thus the protection of passengers. Fire alarm systems must therefore be protected against damage caused by lightning and surges.

In order to protect underground stations comprehensively, the lightning and surge protection concept provides for the use of BLITZDUCTOR XT surge protection modules on all connected lines of the fire alarm control panel. Possible differences in potential were also taken into account in the protection concept. For this purpose, LSA technology and BLITZDUCTOR XT devices with a gas discharge tube were installed as required.

BLITZDUCTOR XT with monitoring function enables continuous status monitoring of the arrester and quick and easy testing without removing the module.

For direct earthing of unused connection wires, the BLITZDUCTOR XT earthing module or an LSA earthing plug was used. The indirect earthing was economically resolved using LSA connection technology with gas discharge tubes.