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Managing processes, the advantage of using IMCS under increased plant performance requirements Author: Gunnar Zank, ABB Low Voltage Systems Part One: AN ANALYSIS Low voltage motor control centers and switchgears are a vital part of an industrial plant. Whether oil refinery, pharmaceutical plant or paper mill, reliable motor control is a mandatory part of a successful plant operation. Electric motors were once considered connected when the electrical part in switchgear was tested and drive shaft was correctly attached. Motor starters were once considered only to be means of starting and stopping the motor by a push button station and in addition provide a general thermal overload protection. Control and protection philosophies were based on conventional methods. However, microprocessor technology was first introduced into motor starters two decades ago. This was a significant development improving the motor protection functions, monitoring and allowing digital control. Following the emergence of open field bus technology more than a decade ago, intelligent motor control system (IMCS) has rapidly gained ground in terms of user confidence. Already considered mature in certain industry applications an IMCS provides extended information and process data. Widely proven communication network protocols like PROFIBUS or Modbus are permitting serial process control application. Communication robustness and response time suitability make this technology reliable for real-time applications. Intelligent motor controllers are becoming an integral part of a plant control and management system. The ongoing pursuit of lower cost, greater availability, optimized maintenance and higher safety levels has leveraged a platform for flexible engineering that provides shorter commissioning times, advanced information, better diagnosis and simplified troubleshooting all leading to less downtime. Plant managers are seeking further productivity gains through better overall plant uptime and coordination of operations and maintenance. The key in achieving this is delivery of the right information to the right people at the right time. This would not be possible without the appropriate connectivity of an IMCS. New system architecture and communication configurations are adapting to better meet this demand.

Product aspects Past situation Current trends

Starter module Huge numbers of different application and modules

Highly standardized yet flexible configuration

Intelligent functions Optional Embedded and In-built by design yet independently accessible

DCS Communication Single master and dedicated interface

Scalable with multiple mastership and meaningful integration

Configuration possibility Point to point Multiple combinations yet highly optimized, possible to enhance at any stage of project life cycle

Information Too much and not in context Pertinent and precise to operator need

Table 1

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SCALABLE APPROACH The demand for a higher information, flexible communication and data processing is different for the different industry. Although with a common target of highly optimized plant operation and availability the approach and expectation varies with the customer. Leading technologies are adopting a scalable approach. An IMCS does not need to be complicated. Simplicity and scalability is the key factor for such requirements. The possibility to build a MCC in certain levels, packages and upgrade facilities at any stage of a project or plant life cycle is considered.

Work place safety has become a priority when considering IMCS. There is a growing demand from separating different voltages. An independent access to electrical components and cables as well and independent control and protection part allows the personnel to work in its dedicated areas safely and conveniently. Interferences, either personally or electrically are eliminated. The power side of the IMCS is interlocked behind closed doors enabling a control technician to work on the IMCS control part in complete safety without the need to shutdown the switchboard.

CONFIGURATION VARIABILITY IMCS applications for process industries require various different system configurations to meet different customer plant operation philosophies or site-dependent demands on information flow. Multiple motor starters can be accessed via a central communication unit: This approach allows simultaneous access from several control locations on different communication interfaces. Further, certain tasks like adding motor starters for plant extension or modifying configurations are supported through higher system flexibility. Motor starter are fully standardized modules yet allowing a flexible use through programming facilities. Complicated starter control functions, conventionally build with relays are history. A high number of different starter types, control schemes and spare parts are no longer a headache for plant maintenance. Of the shelf starter modules, easily available and interchangeable between plant locations, withdrawable technology with inbuilt wiring reducing the time for repair. The high level of integration in a plant operation environment and the need of access to motor controller by control system personnel independently of the electrical part are reflected in the IMCS. Motor controllers are conveniently located outside the motor starter yet connected through inbuilt wiring technologies. To access them there is (theoretically) no need of coordination between different plant maintenance sections anymore as the electrical part remains untouched. The integration of the IMCS into the plant asset management system allows an optimized maintenance process. Failure analysis, maintenance trigger and spare part handling are the key to higher operational performance of the plant. Maintenance data of the IMCS and motor are helping to optimize the maintenance up to a truly predictable maintenance allowing optimal plant up time. Part 2 of this series will detail this more.

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RELIABILITY The IMCS monitors at any point of time the correct location of every motor controller and its starter module. It also ensures that the correct control and protection function is applied. Mixing modules or inserting wrong type of modules does not lead to mal operation of motors anymore. Communication integrity with predictable behavior in case of a failure is mandatory to ensure motor availability under different circumstances. The operational safety of a motor is ensured against breakdown in communication through continuous monitoring of the communication integrity from the motor starter to the process control system (DCS: Distributed Control System) at all times. And, should communication break down, the motor is led to a pre-defined safe state. Further, the possibility of control from different location is safeguarded by providing a controlled user access right mechanism. At any point of time it is clear which location can or even has operated a motor. COMMUNICATION CAPABILITIES A standard fieldbus did not emerge by today; preference varies between customers and control systems. Majority is given to Modbus and PROFIBUS with the emergence of Ethernet based application Modbus TCP and PROFINET.

Beside a proven fieldbus communication interface to process control systems the IMCS provides far more data than needed in a process controller. Delivering that information to the right location is combined with the limitation in fieldbus capabilities and a huge engineering effort of the DCS. Advanced IMCS eliminating such situation by providing multiple data access through central communication units or data concentrator.

The use of standard fieldbus communication is reduced to its basic function to transfer process control related data, minimizing the engineering effort to its base. Advanced information is available through Ethernet based interfaces. Today it is all about information flow to the right operator at the right time and the magic word is OPC (OLE – Object Linking and Embedding – for Process Control). OPC is a standardized way of handling additional information that is not mission critical, but nevertheless important for successful plant operation and asset maintenance. Using OPC, customers can connect to operator stations, maintenance systems and other applications etc. directly without having to program a process controller. By using OPC Servers provided within the scope of IMCS, additional information for operators can be added to the faceplates without additional engineering and configuration effort in both the DCS and the IMCS. Alarm and event handling is totally automated so operator stations obtain motor relevant alarms and time-tagged events directly from the motor controller. The maintenance relevant information can be taken directly via OPC to the electrical maintenance system or SCADA package. With this approach the information required can be resented as required and where it is needed.

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MNS® iS ABB is offering an IMCS solution with MNS iS (iS stands for integrated Solution) as part of their proven Low Voltage Switchgear System technology MNS®. MNS iS is a compact IMCS integrating LV Distribution and Motor Control Center technology in one single switchgear application. Each motor starter or feeder uses its own withdrawable unit and a control unit. All control units (MControl) are located in a separate compartment, offering access independently and safely whilst fully separated from power parts, starter and feeder module (MStart and MFeed) in the switchgear. Electrical starter and feeder modules are widely standardized in order to reduce the numbers of different components for easier maintenance and spare parts handling. Advanced data are collected and analyzed to provide high information value for optimal Asset Management. Maintenance data are extended to cover both electrical and mechanical aspects. Local and web server based control and monitoring possibilities are extending the solution to allow monitoring from virtually any location in the switchroom and plant wide. The communication between the MNS iS control modules to DCS or SCADA systems is using standard fieldbus protocols like PROFIBUS and Modbus but also Ethernet protocols such as Modbus TCP. A real-time Ethernet based communication internally ensures data availability and consistency between the control unit and the communication interfaces. As an open interface to any SCADA or DCS integration MNS iS provides an integrated and configuration free OPC Server application, which allows seamless integration into the plant operation and asset management system and application. Standardized interface components based on off-the-shelf products allow easy maintenance and upgrade of the system for future enhancements. �

Follow up this series with Part Two: Advanced Asset Management with IMCS

About the author: Gunnar Zank is Regional Support Manager for the MNS® iS system in Asia-Pacific and Middle East. His 16 Years of working experience with ABB ranges from automation control systems and fieldbus communication to the development and integration of IMCS solutions into control systems and plant applications. He was leading the global technical support team for ABB’s IMCS solutions and is now based in Singapore. Contact: Email gunnar.zank@sg.abb.com ABB Industry Pte.Ltd. 2 Ayer Rajah Crescent Singapore 139935