Fast bus-transfer techniques for maintaining full plant production

Residual-voltage and delayed bus-transfer operations often result in severe process upsets or complete loss of plant production. It is noted that fast transfer techniques might solve such problems, but it is questionable whether they can be safely and effectively applied in petroleum and chemical plants. The author attempts to answer this question by reviewing the strengths and weaknesses of all fast and in-phase transfer schemes, including the newly developed fast transfer switch (FtS). IT is shown that high-speed, in-phase, and Beckwith systems may be applicable to special situations in which inertias are high and initiation is by manual or equivalent means. These schemes should be avoided where initiation is by electrical faults unless the fault type and location are predictable and a full transient analysis is performed. The FTS system is seen to be applicable to loads of any inertia, whether initiated by faults or otherwise. Thus, it appears to be well suited to virtually all petroleum and chemical plant applications. Its main drawback at the present time is a lack of industrial experience with it