Safety for Particle Accelerators

In Germany's largest acceleration center, DESY (Deutsches Elektronen-Synchrotron), the company SSP Safety System Products ensures the safety of scientists using trapped key interlock systems from Fortress Safety.

Anyone entering the gigantic, extensive, and winding halls of DESY in Hamburg will find themselves in a small adventure.

Throughout the year, alongside DESY's own 700 researchers, you can observe up to 3,000 scientists—who can rent space at DESY for a few days—tinkering and pondering.

Research at DESY is highly versatile: scientists search for the world's smallest building blocks of matter, develop materials, or test new mechanisms of action for future medicines. In other words, vital fundamental research aimed at helping to master the challenges of the future, such as climate protection, health, or energy supply.

The Challenge

One of the large-scale devices at DESY is the brilliant ring PETRA III. When it was inaugurated in 1978, PETRA was the largest accelerator in the world. Initially, it functioned as a "collision machine" for particle physics, and later as a pre-accelerator for the even larger HERA ring. Afterward, it was converted into the most brilliant light source of its kind: since 2010, PETRA III has been providing X-ray radiation that is stronger and more tightly focused than at any other storage ring in the world.

Safety Requirements

To ensure that research teams from all over the world can work safely, high safety requirements apply across the entire DESY research site. Particularly in the experimental stations where scientists can independently install their test setups and conduct experiments with X-ray radiation, personal protection through safety products is enormously important.

A particular challenge for the safety team at DESY was posed by the so-called "user chicanes". These chicanes are hatches used to feed various media into the danger zone. Depending on the setup of the experiment, these can vary, which is why the research teams must also be able to open and close the chicanes independently. To ensure that the chicanes are closed before the experiment begins with the X-ray radiation, DESY utilizes a trapped key interlock system according to DIN EN ISO 14119:2014-03 from the company Fortress Safety in Wolverhampton, England, which is integrated into the safety circuit.

Trapped Key Interlock System Ensures Safety

Fortress Safety is known for its extremely robust safety guard locking, which can be configured according to customer requirements and functions purely mechanically—entirely without wiring—through the use of a trapped key interlock system. DESY took advantage of this benefit on their chicanes to save themselves extensive wiring and control efforts. With the intelligent combination of a trapped key interlock system and guard locking, the mGard guard matchlocks solve almost any safety application up to SIL3 (EN/IEC 60261) Category 4 and PL e (EN / ISO 13849-1).

If a researcher wishes to open the hatch, they must first remove the main key from the control panel.

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This key is held in place by a solenoid-controlled switch, meaning it can only be removed when the system is in a safe state and an enable signal is received from the safety controller. With the key, they can only open the purely mechanical safety guard locking.

As long as this is open, the key remains trapped. Only when the safety guard locking or the chicane is closed again can the key be removed. Now it can be reinserted into the main switch and the system can be started. Another highlight of the amGardPro series is the "Extracted Key" function, which offers optimal protection by allowing personal safety keys to be removed.

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The principle of operation is incredibly simple: before maintenance personnel enter the system, the safety key must be pulled and taken into the system with them. If the safety door is then accidentally closed, the system cannot be started without the key.

If multiple chicanes need to be opened, it is possible to use a key exchange box, which is also purely mechanical.

When the key from the main switch is inserted here, the other keys are released and can be used to open the many chicanes. In accordance with the EN ISO 14119 standard, all keys possess the highest level of coding, so that manipulation or incorrect operation of the keys is completely excluded. To make handling as intuitive as possible, the keys and locks are labeled and color-coded.

At DESY, what is appreciated most about the trapped key interlock system is its ease of use—after all, everyone knows the principle of opening doors with keys!