Exam Question
Explain the term "cascade control" and sketch such a system suitable for use with a main engine jacket cooling water system. Show the variation of pressure and temperature at major points of the system. (16)
Class 2 (2nd Engineer)
MEKM
📅 Oct 2024
Reference Answer
A temperature-controlled HT (high-temperature) circulating system is a good example of a control system that can be enhanced by the inclusion of cascade control. The system involves two controllers in cascade, each equipped with its own temperature sensor.
The first controller (outer loop) regulates the temperature of the water outlet and utilizes a PI (proportional-integral) controller.
The control valve is located far from the outlet, where it accurately measures the temperature.
The error term of this first PI controller is the difference between the desired HT temperature and the measured temperature at the outlet.
The first controller (outer loop) regulates the temperature of the water outlet and utilizes a PI (proportional-integral) controller.
The control valve is located far from the outlet, where it accurately measures the temperature.
The error term of this first PI controller is the difference between the desired HT temperature and the measured temperature at the outlet.
Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.
Prepare on Android — MeoMock on Google Play