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Challenge

Door and gate systems from cool it Isoliersysteme GmbH, based in the Lower Saxony town of Melle near Osnabrück, are used throughout Europe in cold storage facilities and freezer rooms. The specific conditions prevailing there include high mechanical burdens, from forklift trucks, for example. Given this background, German manufacturer is continuously working on ways to further increase the safety standards for their products. In the area of heating cables and additional electrical systems in the door, this is achieved by means of the 5SM6 AFD unit from Siemens.

 

Tough ambient conditions are a normal part of the refrigeration business: Among other areas, this applies to low temperatures, as well as moisture and wetness due to regular cleaning cycles. "Cool it" meets this special challenge by providing high functionality of its doors and gates, as well as high mechanical quality, right down to ramming protection. Nonetheless, amid hectic operations with forklift truck and floor conveyor traffic, collisions with doors and gates cannot always be avoided. In the process, the integrated, internal electrical equipment can become damaged without at first being apparent from the outside. Special technical devices used already in the door controller, such as MCBs and RCCBs, are intended as a safeguard against this. However, both devices are not capable of detecting serial arcing faults. These frequently occur in crushed or otherwise damaged cables – and due to the enormous heat developing in selective points, they may cause a scorching or even smoldering fire. It is absolutely essential to avoid this, particularly in the food processing industry. Because even the smallest occurrence of smoke emissions requires by law the disposal of all the goods affected. In seeking an appropriate solution to further increase safety standards, also in this special area, the "cool it" company paid special attention to the heating cables inside the outer seal, preventing the door from freezing shut. 

Solution

"cool it" found what it was looking for at Siemens: The 5SM6 arc fault detection device detects dangerous arcing faults automatically with high reliability. It is used in combination with an MCB or with RCBOs. In case a fault is detected, it instantly disconnects the affected circuit safely. Since the summer of 2015, "cool it" has offered the arc fault detection device as an option, and for some models, even as a standard feature. One such model is the flexible door, a two-section, rapid sliding door for logistics areas with flexible door panels. The design is more tolerant to accidental hitting by a forklift truck compared to a conventional door, thus safeguarding against an occasional moment of carelessness in areas where there is extremely heavy traffic. As a result, however, there is a high burden on the integrated electrical equipment. That is why up to now the flexible door model has already been standard equipped with a residual current circuit breaker, which in the meantime has been replaced by a combination of arc fault devices and RCBOs.

Benefits

With the Siemens innovation, "cool it" can boost its safety standards, which always already exceeded existing directives, even further.

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The AFD unit with its additional protection represents an additional component in the safety package that was previously not available in the past. Previously, the solution was successfully validated in Siemens laboratories specifically for the applied heating cable model. The protection component is installed directly in the controller housing of the door. This offers the advantage that when tripping occurs, faults can be selectively indicated. In other words: There is no need to seek the fault in a central distribution, it is immediately clearly pinpointed. This appropriately allows for rapid response in order to restore normal operations as promptly as possible.