- To/from wiring termination schedules
- Daily cutover plans
- Third-party device considerations
- Loop check spreadsheets or folders
- Written cutover methodology.
The consideration of the sequence of cutovers is most critical when systems must stay in operation. In this scenario, there are typically intermediate operator consoles for parallel operation. Planning must include consideration of temporary power requirements and temporary locations for panels and/or consoles.
An area not commonly addressed to an adequate level in cutover planning is third-party device communications. The details involved in migrating serial communications can often be very complex. Whether the communication is a serial RS-232 connection to a weigh scale or a redundant Modbus communication to a triple-redundant shutdown system, the impact of migration to a new control system must be researched in great detail in advance of actual cutover.
Keys to Success
Good migration cutover plans include individual third-party device cutover plans. Quantification of points, types of communications protocols, specific driver compatibility issues, data mapping requirements and operating system version compatibility should all be defined.
Detailing all aspects of a cutover early in a project will pay great dividends in streamlining cutover time, cutting costs and reducing overall risks.
Intermediate Operability and Training Plans
A common challenge for migration projects is establishing parallel operation of the old and the new control system as this is often the operators’ first exposure to the new system. There are a few items that must be addressed.
First is consideration of how to physically layout the new control system without interruption to the existing operating environment. This is challenging as most often control room space is limited. As parallel operation begins to occur during the cutover process, consoles must be in close relative proximity and/or additional operating staff must be used to supplemental plant operations on a short term basis.
A second consideration closely integrated into the cutover efforts is determining the sequence of units, processes and/or systems to group and cutover. For example, if a reactor is going to be cutover to the new system, then it is essential to plan the conversion such that the operator is only required to utilize two systems to operate the reactor for a minimum amount of time.
Another consideration is the overall operator training plan. One of the questions is when to start the operator training. If the training is done well in advance of cutover, then it often proves less effective. However, training during the cutover also doesn’t work well due to distractions.
A better method is to train a core group of operators and make them part of the cutover team. The training for the general population of operators then takes place after the cutover and involves additional training by the core operator team.
The type of operator training is often a source of discussion as well. Formal operator training may not provide technicians with adequate hands-on application specific training. The type of operator training selected comes down to personal preference of the company, but one suggestion is to establish a combination two-level operator training plan. The first level is basic skills, navigation, and system familiarity training - similar to formal vendor training. The second level is application specific training that utilizes actual plant processes, graphics and alarms.
Migration projects are challenging, but can deliver great value to end users. The process used to arrive at migration timing and scope has considerable influence on whether that value is actually achieved. The most critical consideration is detailed up-front planning because it lowers risks in the execution phase of a project.
It is generally not the obvious portions of the scope such as configuration of the new system that creates issues for migration projects. Instead, less obvious areas such as infrastructure, HVAC capacity, power limitations and third party device integration cause unforeseen problems. When approaching control system migration, consider the application of these best practices to lay the groundwork for a successful project.
Nigel James is president of the Gulf Coast division of Mangan Inc., a system integrator in Lake Jackson, Tex.