DART - Developer Dialog Reveals Tangible Solutions
Experts from interested manufacturers, PTB and Pepperl+Fuchs quickly agreed that point-to-point supply with more available power would be beneficial to many applications using current methods of explosion protection. For example, the precision of a flow meter based on corriolis measurement principles can be improved with increased power. The influence of cavitation on the measurement is smaller, or even irrelevant. The additional circuitry that is required is more than compensated by reduced material and installation costs, and sophisticated methods of explosion protection, such as flame-proof and increased safety, are no longer needed.
It became clear that a supply with 24 V and max. 12 W would satisfy the needs of all developers and would be easy to implement. The cable length is relevant to the amount of power available to the instrument. Cable lengths between 10 and 1000 m were discussed. Of interest, though possibly for a second step of development, is the transmission of digital data, which could be transmitted simultaneously with DC power through modulation.
PTB is promoting internationalization. As a first step, the evaluation for system safety and the testing procedures are recertified in close cooperation with other competent institutes. This collaboration helps generate a universal acceptance for the testing procedures that will be introduced into a technical specification (TS) of the IEC, and eventually find its way into the IEC-standard 60079. All parameters must be defined for safety and are required for conception of systems (supply, cable, load) including functional and safety-related constraints. The common objective is clear: to create interoperability for EPCs and end users so that plug-and-play becomes reality. During a kick-off meeting in June 2009 at PTB, many participants of the original information event joined the industry-financed project headed by PTB to develop all necessary standardization in preparation for the IEC TS. The line is still open for more companies to join the effort. A paper covering the details regarding requirements for DART-system components will be published during Automation 2009, a conference hosted by German VDI.
Pepperl+Fuchs has registered a patent and trademark for DART (WO 2006/003445). Rights for the use of the technology and for the trademark are licensed to all interested parties in two variations: the “small” license for DART-consumers, and the “large” license for the complete DART-technology: supply and load. As soon as an internationally applicable specification or standard becomes available that defines interoperability for power supply and loads, all license costs will be dropped. Today’s developments have progressed; first solutions will be available soon.