Migration: Migration: picking the picking the right moment

摘要

Not everything improves with age. Control system performance generally degrades over time. As systems near obsolescence, control strategies fail to take account of changes in the plant, resulting in declining operating performance, reduced reliability, rising maintenance cost, and difficulty in sourcing affordable spares. Eventually, experienced personnel with systems knowledge begin to retire. In fact, the cost of the distributed control system (DCS) is relatively trivial in comparison to the outsized impact it has on plant performance and the cost of lost production from unplanned downtime. Yet the number of control systems in operation that are two or three decades old shows that many manufacturers delay migration as long as possible. In most cases, the rising costs of obsolescence alone are not enough to prompt the change. Instead, some other factor forces the upgrade: compliance requirements or changing demand conditions that cannot be met due to system constraints; or mergers and acquisitions that bring the desire to standardise on a single control solution.