Bridging the Intrinsically Safe Fieldbus Disconnect

Overview:

At first glance, the concept of Intrinsically Safe (I.S.) fieldbus is a study in opposing concepts. After all, fieldbus is about powering multiple devices, while the idea of I.S. is to limit energy flowing into hazardous areas. The fact that multiple devices can be powered from the same wire pair only adds to the design challenged that engineers face when developing their own system. Typically, this can lead to complex installation schemes as users mix wiring methods such as Division 1 and Division 2 (Zones 0, 1 and 2) in order to accomplish their task.

The ideal solution allows users to connect multiple devices (for PROFIBUS PA or FOUNDATION fieldbus H1 networks) without compromising area requirements or using expensive installation methods. Until recently, this was a pipe dream. But recently breakthroughs in design have brought together many of the best features of different I.S. techniques. Specifically the use of the "High Powered I.S. Trunk" concept greatly simplifies the installation and footprint for intrinsically-safe segments.

The sections in this white paper provide an overview of the existing technologies and methods that fieldbus users have at their disposal when they embark upon designing and installing fieldbus in hazardous areas. These sections assume that there is a general understanding of fieldbus segment topology and design.