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Automation Technologies 5/2014

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Automation Technologies 5/2014

Components and Software

Components and Software previous page All individual components are redundantly implemented One or several distributed control cabinets are installed for each module, which are responsible for the processes in this plant area. All of the individual components, from the primary power supply to the wiring for the various loads are redundantly implemented. To supply the distributed control cabinets, two power supplies with 24 V DC and 10 A are connected in parallel on the output side. If one of the power supply units develops an internal fault or if the primary power supply fails, then the second device automatically takes over and completely supplies the loads. The power supply units are dimensioned so that the complete current demand of the connected loads is covered by just one module in all operating states. In each of the thirty distributed control cabinets, there are two Phoenix Contact Quint Power power supplies and one Quint Oring redundancy module with 24 V DC and 2 x 10 A to supply the electronics. Long service life of the redundant supply 01 The pilot plant is a precise emulation of the commercial plant – from the valves to the process control system pilot plant of this size, in which 2,500 inputs and outputs must be monitored, represents a significant investment. “As a consequence, it goes without saying that only high-quality components are used. Production downtimes would be very expensive or, depending on the particular process, could even result in destruction of plant sections”, explains Ruud Mennink, Control Systems Lead Engineer for this project. The power supplies are decoupled so that the load is not influenced by a short-circuit at the output of one of the power supplies or in a feeder cable from the power supply to the decoupling diode. Ruud Mennink selected another solution here, which results in a significantly higher operational reliability. “Instead of the usual decoupling diodes, we use Quint Oring modules from Phoenix Contact.” This involves an active redundancy module, whose function extends beyond simply decoupling the power supplies. The ACB technology (Auto Current Balancing) provides another advantage. This technology doubles the service life of the redundant power supplies by ensuring that both are evenly utilized. „The load current is symmetrically distributed between the two power supply units, which was a decisive criteria for us when selecting the Quint Oring module“, explains Ruud Mennink. When modules are used without ACB technology, as a result of dissymmetry, one power supply unit feeds the load by itself, while the other device remains in the idle state. This results in a AUTOMATION TECHNOLOGIES 5/2014

Components and Software high thermal load for the active power supply and therefore faster aging and a lower service life. If both modules are loaded symmetrically and operate with only half the current, then the operating temperature is significantly lower. This significantly increases the service life of the redundant supply. Quint Oring modules are suitable for voltages from 18 to 30 V DC. Designed for use in harsh industrial environments with temperatures from -25 °C up to 70 °C, MOFSETs (metal oxide semiconductor field-effect transistor) are used for decoupling instead of conventional Schottky or silicon diodes. This alone means that energy consumption can be slashed by up to 70 %. All of the electronic modules are coated Six Quint Power power supply units are installed in a central control cabinet and are decoupled using Quint Oring modules. In this case, the components do not have to be certified for operation in hazardous zones, as this part of the plant is pressurized to protect it against dangerous gases. However, certification according to ATEX for Zone 2 is required for all of the components installed in the distributed control cabinets. Phoenix Contact uses dip coating to provide optimum protection for all of the components mounted on the PCB. Unlike spray coating, dip coating also completely coats through-hole mounted components, such as bridge rectifiers and power semiconductors – as well as the lower side of components, hollow spaces and the edges of PCBs. In addition to the usual industrial approvals, the dip-coated modules and redundancy modules are in conformance with EN 60079-15 (ATEX directive). They may be used in hazardous zones where 3G category equipment is required. The modules are also IECEx certified. For the American market, Quint Power devices comply with UL standard ANSI/ISA 12.12.01 as well as with Class I, Division 2, Groups A, B, C and D (hazardous locations). 02 Zeton B.V., located in Enschede, The Netherlands, develops and produces pilot plants, which accompany process technology applications until they are ready to go to market AUTOMATION TECHNOLOGIES 5/2014


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