· Increase in unit size, growth of interconnected and the need to maintain the system in normal mode require sophisticated control, instrumentation and protection.
· The multiplicity of monitering instruments in the control room and their distance apart make the observation of more than a few vitaloncs almost impossible, especially during the intense activity of plant start up.
· The operation of changing plot parameters and take critical decisions.
· These requirements led to the development and application of more advanced solid state modular electronic instruments, computer based direct control and date processing systems.