Intrinsic safety concept for the fast field bus on the based of RS 485

摘要

The actual tendency to introduce remote I/O-systems with many connected sensors/actors requires a fast bus concept for transmission of the collected data. If for this purpose a RS 485 bus is used and the type of explosion protection Intrinsic Safety is claimed, the high prospective bus short circuit current results in difficulties to be assessed using the data given in EN 50 020 only. A new computer based modeling method of the standardized spark test apparatus' properties widens the scope and produces experimentally validated data for the ignition capability of cables.