Another clear advantage is the proximity of the control system to the process level because this relates to explosion protection: The energy stored by systems providing intrinsically safe signals in hazardous areas must always be limited. For this purpose, distributed systems are much better because shorter cable runs simply store less energy. “Cables are potential energy storage units, which is why we always keep the length of cable runs in mind,” explains Jörn Czysch, an expert at Feige Filling.
The control system of a drum filling machine is installed in a gas-tight cabinet that is slightly overpressurized to prevent explosive gas penetration. A touch-sensitive panel is integrated into the cabinet door, allowing the system to be operated and monitored locally. All of the drum filling system’s sensors and actuators converge within the control cabinet both from the hazardous area (i.e., inside the hermetically sealed filling cabin), as well as from the non-Atex system area (e.g., conveyors).
Feige Filling relies on the Wago-I/O-System 750’s intrinsically safe modules to connect every field device located in the Ex area of the filling system. The system is powered by a supply module that also monitors the power supply to the downstream Ex i segment. Furthermore, this module separates the intrinsically safe from the non-intrinsically safe section of the Wago-I/O-System 750.
High Availability through Standardization
Feige Filling also relies on standard Wago-I/O-System components for the machine areas that require no special explosion protection. The advantage: From an engineering perspective, only one solution is used for system automation — regardless of whether the devices are connected in hazardous or non- hazardous areas.
“It is extremely important that our system designs are very similar to each other,” says Axel Frank, Head of Automation Technology at Feige Filling. “Last, but not least, maximizing our system equipment standardization helps us minimize the probability of failure for individual components.” Because the remote Wago-I/O-System 750 readily covers both hazardous and non-hazardous areas in one system, Feige Filling can always equip the system automation with functional technology without leaving the stability of a standardized system.
* The author is Market Manager Oil, Gas & Petrochemical Industry, Wago Kontakttechnik, Minden/Germany.