Industry News Display
2013-08-27 Control Engineering
When migrating or upgrading your automation system, don’t forget to examine this group of areas outside of the HMI, controllers, and I/O. These suggestions will help you identify and deal with lurking problems early in the process.
By: Matt Sigmon
If you’re in the process of upgrading your automation system, or contemplating such a task in the near future, your primary focus is probably on the HMI, the controllers, and the I/O—and rightly so as these are critical components to address in a system migration. But there’s much more to an automation system than these hardware components, and these secondary areas can be the source of many problems if due diligence isn’t performed in the planning stages.
One of the best ways to examine all areas of the automation system prior to undertaking a major automation upgrade project is to perform a front end loading (FEL) evaluation. A FEL evaluation is a type of analysis that evaluates all aspects of an automation system upgrade or other project. Among other deliverables, it should include a list of project tasks with durations, and an overall project schedule.
Most end users will work with an outside service provider to produce the FEL evaluation because they often don’t have the available manpower. The right service provider will have produced many FEL evaluations for automation system upgrade projects, and can thus help the end user to produce a thorough study in an optimal manner.
A FEL evaluation will help develop a budget and justify the project. It will also reveal potential problems, and help prepare end users for the daunting task of migrating their obsolete DCS or PLC-based automation system. In short, it should provide a map to success with the destination in mind.
In most cases, the amount of time and effort invested in a FEL evaluation is directly proportional to overall project success. Unfortunately, many end users view this stage as an optional task for an automation system upgrade, and perhaps even a distraction. Scrimping on the FEL evaluation not only increases risks, it also can result in missed opportunities for improvements and enhanced long-term sustainability. By contrast, a thorough FEL evaluation will identify potential problems and help ensure that the project attains its goals.
10 areas outside the lines
When the main architecture is developed for an automation system upgrade, the primary components are always the HMIs, controllers, and I/O. Most of the time and effort in the planning and budgeting stages is spent on these key components, often to the detriment of the balance of the system, those areas that fall outside the lines.
A properly executed FEL evaluation will shed light on 10 important secondary areas, which are listed in Table 1 and discussed below.
Field devices and infrastructure
Field equipment and wiring primarily consists of four parts:
- Wiring, conduit, and cable tray
- Panels, cabinets, marshalling panels, and junction boxes
- Instrumentation, including inline devices, analyzers, transmitters, etc., and
- Mechanical equipment, including motors, valves, drives, and other field devices.
All of these items must be examined to ascertain acceptable physical condition and proper documentation. In addition, instrumentation and mechanical equipment must be examined and/or tested to ensure proper interface with the new automation system’s I/O and digital communication interfaces.
The overall condition of field wiring, including terminations, labeling, and grounding, should be assessed during the FEL process. If any areas are not up to standards and in good working condition, plans and budgets should be developed to rectify any deficiencies and defects.
When the automation system is up and running, the status of various field devices such as motors, valves, and position switches is determined by hardwiring these components to automation system inputs. So, the interfaces between these devices and the inputs must be tested to ensure proper voltage levels and electrical isolation.
Similarly, valves, motors, and status lights are driven by automation system outputs. Again, compatibility must be ensured so that each output can drive or actuate its associated device.
Interfaces to automation system analog I/O can be a particular problem area. A 4-20 mA output on an older automation system may have been able to drive more instruments in a loop connection than the new automation system’s 4-20 mA output. This issue would be minor if uncovered in a FEL evaluation, but major if found during commissioning. Moreover, analog inputs must be examined and sometimes tested for compatibility. For example, an older DCS might have accommodated thermocouple types that are no longer in widespread use, and as such may not be supported by the new automation system.
Most plants have smart instruments and analyzers with their own network connections to the automation system (see Figure 1), another area that must be examined in detail during the FEL evaluation.
Network infrastructure and connectivity
Modern automation systems connect to a variety of other systems and components in various layers including:
- Control layer—ancillary control systems on process skids, emission monitoring systems, building automation systems, etc.
- Enterprise layer—historian, MES, ERP, corporate networks, etc.
- Field device layer—HART, Fieldbus, Profibus, DeviceNet, etc., and
- Other—lab systems, remote access, analyzers, advanced process control devices, etc.
The physical infrastructure, including the fiber/copper backbone, network devices, wireless hardware, and other items, must be examined to ascertain acceptable condition and proper documentation. But this is only the first step, as compatibility issues can abound, even when the new automation system supports the very same protocols as the old automation system.
The main interfaces at each layer should be tested to ensure that communications can take place in an acceptable manner with performance equal to or exceeding the existing system. The new automation system must be able to support all of the existing communication protocols, either directly or through protocol converters. In some cases, it may be more cost effective to upgrade or even replace systems and components that can’t easily be interfaced to the new automation system.
For example, if there is a small cluster of instruments with a different fieldbus protocol than the majority of instruments, it may be better to replace these oddballs, as opposed to adding a protocol converter to connect them to the new automation system.
The older automation system will often have controllers and smart devices such as instruments and drives supplied by the same vendor. If the new automation system is purchased from a different vendor, in almost all cases the digital interface to the smart devices will be more limited in functionality, even if the protocol is nominally the same. Provisions must be made to operate the system with this reduced functionality, or to replace the smart devices.
Ancillary systems and space requirements
The new automation system components will be housed in a particular area, usually the control room where the older system resided. The following areas should be examined to ensure that they meet the required specifications of the new system, and the ongoing needs of operations and maintenance:
- Power requirements, including UPS
- HVAC requirements
- Physical footprint, and
- Control room ergonomics.
The UPS and other power systems must have sufficient capacity to handle the new automation system components. Similarly, the HVAC system must be able to keep the new electronics cool while maintaining a comfortable work environment for operators.
Sufficient overall space must be available to house and mount the new system components, including control hardware and operator workstations. Many older automation systems have custom consoles that can’t be used with the new automation system, or that must be substantially modified.
One area that’s often overlooked when a thorough FEL evaluation isn’t performed is the commissioning plan and its effects on the ancillary systems and space requirements. Many commissioning cutover plans call for simultaneous operation of the old and the new automation systems. This can obviously have profound effects, and careful planning is often required to accommodate the operation of both systems at once. Temporary auxiliary power systems are often necessary, along with transitional mounting spaces.
The new automation installation with all its interfaces and connections to field equipment and wiring, network infrastructure, and ancillary systems, will require many changes to documents and drawings.
Certain critical documentation must be reviewed and often updated in order to operate and maintain the new automation system successfully. Some of the most important documents that must be examined include P&IDs, loop sheets, I/O databases, system configuration, software programs, software documentation, batch requirements, functional specifications, control system narratives, and programming and design standards.
Demolition, installation, and commissioning
A thorough FEL evaluation will examine the required demolition, installation, and commissioning services to make sure these activities are properly accounted for in terms of budget, schedule, and available manpower. Manufacturing facilities are typically staffed to handle day-to-day operations, and don’t have personnel available to execute major projects. Therefore, the FEL evaluation should identify the required personnel, and make provisions for contracting for additional forces.
The commissioning plan is a critical component of any automation system upgrade. Major items that must be taken into account typically include shutdown schedules, plans to minimize downtime, and use of hot cutovers. As with other activities related to installation and commissioning, supplemental manpower will probably be required. Provision must also be made to account for plant output typically lost during installation and commissioning.
Construction design activities associated with installation and commissioning should also be estimated and planned in the FEL evaluation so that they can be properly executed. Some of the key activities that may need to be performed included the development of new cable and conduit schedules, instrumentation and field devices drawings and diagrams, panel and enclosure designs, loop sheets, motor elementary diagrams, point-to-point diagrams, and installation details drawings.
Compliance and abnormal situation management
The changes made to accommodate the automation system upgrade will require examination to ensure compliance with all standards, codes, and operating procedures.
Safety instrumented systems (SIS) must be checked to ensure that all required SIL levels are maintained. A layer of protection analysis (LOPA) may need to be performed, and environmental health and safety procedures must be maintained at acceptable levels.
Compliance with current codes and standards such as NEC, NFPA, and FDA regulations must be maintained, often with permits and inspections in the case of NEC and NFPA regulations. Likewise, FDA regulations for validated systems contain a very strict protocol that must be followed for all changes at facilities that manufacture pharmaceutical products. Many food and beverage plants must also comply with FDA regulations when performing changes and upgrades, albeit at a less stringent level.
Your older automation system will have had some informal or formal methods for dealing with abnormal situations. Similarly, the new automation system must also have a method to handle abnormal situations. This is an area that can often be improved upon by simply taking advantage of features built into the automation system, as well by implementing current abnormal situation management (ASM) graphics and alarm management standards and best practices.
In fact, the FEL evaluation should examine all possible areas of improvement, including ASM, as this will ensure the maximum return on investment for the new automation system.
Areas for improvement
The new automation system will typically have features and functions not available with the older DCS or PLC-based system, allowing for improvements to existing operations. Further improvements can result from modifying existing operations and practices, with the automation system upgrade providing an ideal time to perform these activities.
A leading area for improvement is automating processes and systems that were run in manual mode with the old automation system. If manual operation was required because the plant had insufficient components and equipment, then these items will require upgrades or replacements. For example, an on-off valve may need to be modified or replaced so that it can operate as a control valve to automate a particular control loop.
In other cases, the new automation system may allow automation of areas that simply couldn’t be automatically controlled by the older system. Newer automation systems often have advanced process control features built-in, allowing difficult loops to be controlled automatically. Automating manual processes will produce an immediate and substantial return on investment by reducing required operator involvement and consequent human error, by avoiding shutdowns, by improving yields, and by increasing throughput.
Many older automation systems present data and diagrams to plant operators through antiquated graphics displays with low resolution, poor screen quality, and insufficient screen size. By contrast, newer automation systems can take advantage of the tremendous increases made over the past few decades in terms of improved operator interface hardware and software to reduce operator fatigue, facilitate training of new operators, and improve abnormal situation management.
An automation system upgrade can replace an obsolete system with one that can be supported and maintained more easily, but it is also an ideal time to make major advances in operations. Simply replacing like-for-like is a huge lost opportunity. In order to take full advantage of an upgrade and minimize risk, a thorough FEL evaluation must be performed to examine all areas that will be affected by the upgrade, including those outside of the HMI, controller, and I/O.
Matt Sigmon is director of DCS Next at MAVERICK Technologies.
- Process control system migration and upgrade projects often require more analysis than most companies realize.
- A systematic approach to analyzing the project early can help avoid problems and identify opportunities for improving performance.
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