Page 347 - Introduction to Marine Engineering

320 Instrumentation and control

Bridge control

Equipment operation from the machinery control room will be by a
trained engineer. The various preparatory steps and logical timed
sequence of events which an engineer will undertake cannot be expected
to occur when equipment, is operated from the bridge. Bridge control
must therefore have built into the system appropriate circuits to provide
the correct timing, logic and sequence. There must also be protection
devices and safety interlocks built into the system.
A bridge control system for a steam turbine main propulsion engine is
shown in Figure 15.43. Control of the main engine may be from the
bridge control unit or the machinery control room. The programming
and timing unit ensures that the correct logical sequence of events
occurs over the appropriate period. Typical operations would include
the raising of steam in the boiler, the circulating of lubricating oil
through the turbine and the opening of steam drains from the turbine.

Figure 15.43 Bridge control of steam turbine plant