Preventive fire protection: Here, the only thing burning is a desire for learning

For the school community at the Carolus Magnus Secondary School in Übach-Palenberg, Germany, the highest safety standards are the utmost priority. 320 arc fault detection devices provide for preventive fire protection. This makes the installation among the largest of its kind in Germany.

A teaching staff of approximately 50 prepares the student body of some 690 pupils to earn secondary school leaving certificates for university, colleges of applied science, and colleges of further education or intermediate secondary education. The safe operation of the school building, erected in 1967, is guaranteed by regular modernizations and technical inspections at regular intervals. 

 

A routine inspection of the decades-old electrical installation according to accident prevention regulations for electrical systems and equipment of the German social accident insurance (DGUV) recently confirmed the substantial need to take action in the area of distributions: The bottom line: "It soon became clear to us that something had to be done", said Michael Göttgens, managing owner of the contracted installation specialist, e-line GmbH Elektro- und Anlagentechnik from Baesweiler, Germany. The technical decision-makers in the city administration of Übach-Palenberg shared this assessment and contracted with the installation specialist to implement the necessary measures.

State-of-the-art power distribution and electrical installation

During the summer vacation of 2016, all 13 distribution units in the building, including supply lines, were then rebuilt. To secure escape routes, some of the distribution systems were equipped with new, fireproof enclosures with E30 fire doors, capable of withstanding a fire within the distribution for at least 30 minutes, which would thus prevent the fire from spreading. 

 

As a professional electrician, Göttgens is not only familiar with pictures of charred contacts, socket outlets and cables. He knows that electricity is one of the most common causes of fire. Damaged cable insulation, crushed cables, bent connectors, loose contact points or faulty terminal equipment – many damaged points in the electrical installation may cause undesired arcing faults, which can trigger selective heat development of up to 6,000°C and in an extreme case, set off a fire. And in the more than 50 year-old building, potential fire loads also exist, e.g. in the form of wood paneling. Thus, Göttgens was able to convince his contractee to also opt for preventive protection of absolutely every electrical circuit by means of arc fault detection devices. Installed in the distributor, the AFD units dovetail perfectly with the existing circuit protection devices.

 

In the Carolus Magnus Secondary School, there are miniature circuit breakers (MCBs) deployed everywhere. The modular design of type 5SY60.. L+N in 1MW (modular width) offers decisive advantages, which Göttgens also appreciates. "As a result, the AFD unit function can be combined with any MCB of the 5SY60 series. This also simplifies stock keeping."

The AFD unit can be combined with any MCB of the 5SY60 series. This also simplifies stock keeping.
Michael Göttgens, managing owner of e-line GmbH Elektro- und Anlagentechnik, Baesweiler, Germany

Recommended as the accepted state of the art

In the United States, AFD units, known as AFCI (Arc-Fault Circuit Interrupters), have been mandatory protective component for many years now. The International Electrotechnical Commission (IEC) and the European Committee for Standardization (CENELEC) have all recognized the urgency of the matter as well: With the publication of the installation regulation IEC 60364-4-42 or HD 60364-4-42, the installation of AFD units is recommended as the "accepted state of the art". Since then, this recommendation has gradually been transferred into national standards in the EU states. For example, in Germany the current VDE 0100-420 standard calls for mandatory installation of the AFD unit for single-phase branch circuits up to 16 A in numerous applications.

Picture credits: Siemens AG/Wolfgang Geyer

The 5SM6 arc fault detection devices are part of the integrated Sentron portfolio from Siemens. The technical basis of the arc fault detection devices is the SIARC patented detection technology from Siemens: The devices continuously measure the intensity and duration of episodes of high-frequency (HF) noise associated with the voltage and current and the gaps between them. An integrated microcontroller analyzes these signals and triggers the disconnection of the connected circuit within fractions of a second if anything unusual is detected. The arc fault detection devices are able to distinguish harmless causes of faults, such as can arise when operating power drills or vacuum cleaners, from hazardous arcs.

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