The world's first real IEC 1158-2 compliant fieldbus installation with certified field devices operating in Ex Zone 1 environments with power on the bus has been installed successfully at Wacker Chemie's chemical production plant near Cologne.The application comprises 14 buffer tanks equipped with 24 PROFIBUS-PA sensors and actuators supplied by Endress + Hauser, Bürkert and Pepperl + Fuchs.
The first part of the project consists of two identical plant sections, each equipped with 7 level, 1 mass flow and temperature transmitters, as well as 1 magnetic pilot valve. These components are linked together with PROFIBUS-PA and connected via 4 segment couplers to the non-IS PROFIBUS-DP host control system. The PROFIBUS-PA field devices may be operated locally at each device, or from the central engineering tool Commuwin from Endress and Hauser. Here, all device parameters can be stored, documented or modified. This improves transparency and security of the plant.
Wacker chose PROFIBUS-PA because of its simple and cost effective transmission technology (IEC 1158-2), which enables powering of the station over the bus. Only two wires are used to carry both data and power for all devices. The result is a cost reduction of more than 50% in comparison with todays analogue 4-20mA technology.
Based on the good experiance with the new system, a second phase comprising a storage tank field-equipped with approximately 200 PROFIBUS-PA sensors and actuators followed this first installation.