The cars of the inclined lifts of the Parisian Eiffel Tower had been renewed all-round in recent years, important safety components were also replaced.

The cars of the inclined lifts of the Parisian Eiffel Tower had been renewed all-round in recent years, important safety components were also replaced. (Photo: © Anna Efetova /

PESSRAL: new era for operators and manufacturers


Programmable electronic systems are replacing safety-relevant mechanical components to an increasing extent. This considerably simplifies and accelerates both inspection as well as maintenance.

TÜV Süd explains how lift operators and manufacturers can benefit from digitalisation and what this has to do with the Eiffel Tower.

Lifts continue to be one of the safest means of transport. Up to now, their safety-related functions have for the most part been realised by mechanical-electrical components. For example, most lifts have separate shaft copying and speed governor equipment in addition to landing, limit and inspection switches. Electronic components have to date been fitted with safety functions only in isolated cases.

Programmable electronic systems, so-called PESSRAL (Programmable Electronic System in Safety-Related Applications for Lifts) bundle these functions and in this way replace mechanical components that are maintenance-intensive and prone to aging.

The software-aided systems permit a higher safety standard, because they react dynamically to dangerous situations. Fewer components mean lower procurement and maintenance costs as well as shortened standstills due to inspections or repairs. The risk of accidental faults, for example due to material fatigue, also falls.

Remote monitoring and predictive maintenance

The maintenance effort also declines thanks to new options for remote monitoring and remote services. Operation can be monitored via the IoT (Internet of Things) and anomalies detected immediately – the basis for predictive maintenance: maintenance measures and repairs can be planned on a long-term basis and the budget better calculated after risk-oriented prioritisation on the basis of lift-specific reliability characteristics calculated for components and subsystems.

Software is subject to no accidental, i.e. unavoidable, errors. It cannot age, deteriorate or wear out. Systematic errors must receive correspondingly greater attention, e.g. interpretation errors of the software functions. They can be avoided with the help of suitable quality controlling on the basis of a management system for functional safety.

The danger of intentional errors due to hacker attacks is new. Consequently, cyber security also has to be integrated in the life cycle of functional safety. This results in new requirements for operators and maintenance companies: they have to ensure physical access to the lift controller and regularly check and update the safety-relevant software. Other points affect the configuration of the data-related networking and the management of authorisations, passwords and authentications.

Tailor-made solution for the Eiffel Tower

Due to their individuality, inclined lifts, as tailor-made lifts with the latest safety functions, are often technical pioneers and ground-breaking for the sector. When it comes to the much more cost-intensive special solutions, developers usually have a higher budget to explore new technical possibilities. These in turn define the altered state of the art.

This is also the case in the inclined lifts of the Parisian Eiffel Tower. In the course of an all-round renewal of the cars in recent years, important safety components were also replaced. "Renovation of the north lift, in addition to more efficient equipment, will improve the reception conditions for visitors as well as the work of the SETE employees, which is simplified by the more modern lifts," explained Stéphane Roussin, project manager at the Eiffel Tower operating company SETE.

Among other things, PESSRAL is intended to replace the electronic speed governor. TÜV Süd was commissioned with the type approval test of individual components. The special feature of PESSRAL: the testing company already has to develop reliable testing procedures now for systems that will determine the lift world in future.

Consequently, operators worldwide will benefit from the developments for the Eiffel Tower. Like other special solutions, it also serves as a prototype for modern safety functions and their testing.

Jonas Conrady is department head New Technologies, TÜV SÜD Industrie Service GmbH. Dr Rolf Zöllner is Head Business Development Lifts, Cranes & Conveyors TÜV SÜD Industrie Service GmbH.

More information:

The EN 81-20/50 standard series describes safety rules for the design and installation of lifts. As a result, the series specifies the requirements of the European Lift Directive 2014/33/EU. Annex A of EN 81-20 includes a list of electric safety installations. They can be realised by safety functions that have to correspond to the functional safety requirements.

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