ChallengeAs far back as 1876, chemical wholesaler Carl Hugo Erbslöh had soda products, salts, chlorinated lime, and even sulfur imported from Italy in his portfolio. Since then, the company, originally founded in Düsseldorf, has grown into an internationally renowned trader in specialty chemicals and industrial minerals, with a staff of 125 worldwide. The customers of C.H. Erbslöh GmbH & Co. KG come from all sectors – whether it be the food, cosmetics, plastics, or electronics industries. For this highly-specialized requirement, the company stocks some 2,800 articles. Up to 4,000 tons of chemicals and minerals are stored in state-of-the-art high-rack units and tanks at the company’s current location in Krefeld, Germany. The fire safety installations meet the highest standards, including the legal requirements imposed on the chemical industry. And these standards also pertain to the company's electrical installations. Several 5SM6 AFD units from Siemens offer preventive protection of laboratory and staff against fires caused by electricity.
A beginning smoldering fire in the laboratory in the fall of 2014 revealed a previously undetected weak spot in the electrical installation: The heat development was triggered by loosened terminals on the outlet. This led to high temperatures, which proceeded to gradually melt the PVC insulation of the wires, allowing the copper to develop breaks. In the damaged spot, serial arcing faults then developed. They can cause selective heat development of up to 6,000°C. In seeking an appropriate solution for protecting the laboratory socket outlets against these types of risks, the first step was to switch over to finger-safe terminal covers on which no screws can become loosened. Nonetheless, initially the specific risk due to serial arcing faults could not be mitigated with traditional protection devices. Because MCBs and RCCBs are not designed to detect such faults.