Page 343 - Introduction to Marine Engineering

Instrumentation and control 317

Figure 15.41 Cooling water temperature control

system such as this can be used only after careful analysis of the plant
conditions and the correct sizing of equipment fitted.

Centralised control

The automatic control concept, correctly developed, results in the
centralising of control and supervisory functions. All ships have some
degree of automation and instrumentation which is centred around a
console. Modern installations have machinery control rooms where the
monitoring of control functions takes place. The use of a separate room
in the machinery space enables careful climate control of the space for
the dual benefit of the instruments and the engineer.
Control consoles are usually arranged with the more important
controls and instrumentation located centrally and within easy reach.
The display panels often make use of mimic diagrams. These are line
diagrams of pipe systems or items of equipment which include miniature
alarm lights or operating buttons for the relevant point or item in the
system. A high-temperature alarm at, for instance, a particular cylinder
exhaust would display at the appropriate place on the mimic diagram of
the engine. Valves shown on mimic diagrams would be provided with an
indication of their open or closed position, pumps would have a running
light lit if operating, etc. The grouping of the controllers and
instrumentation for the various systems previously described enables
them to become part of the complete control system for the ship.