Command and control of systems and machines follow inevitable logic processes in sequence as represented with figure below. They do not over ride each other. An automatic control system does not apply any command sent if logic flow is not correct. A well-designed ERS does not warns Marine Engineer in case of a mistake only, but also prevents possible malfunctions as well as accidents. Command signals, sent by command elements, are confirmed by monitors displaying the feedback control signals. Marine Engineers must be familiar with command-and-control algorithm and relationship. A well-designed ERS with these features will enable Marine Engineers to send right commands and make proper observations, analyzes, definitions for making right decisions and take right corrective actions.

 

A typical command and control algorithm

Here, “A” is the command voltage which is 24 VDC, “B” is “ON-OFF” switch to send command signal to the solenoid of the contactor in the control panel. “C” is the command signal data line, “D” is the motor starter panel, “E” is the line voltage, “F” is the solenoid actuator, “G” is the contactor, “H” is the electric motor to drive the pump, “İ” is the sensor measuring pump shaft rpm, “J” is the fluid input to the pump, “K” is the 2-40 mA data signal from sensor to the controller, “L” is the controller and “M and N” are the digital and analog monitors (indicators). Algorithm designer may add more sensors for safety and operational requirements. It can be easily seen in figure above that; all process consists of inevitable and irreversible chain events that happen in sequence depending to the algorithm predetermined. This phenomen is the basics of automatic control applied to the machine and system operations.

Last modified: Wednesday, 3 May 2023, 1:01 PM