Ship controllers are the crucial parts of the marine industry
Controllers are pivotal parts of the ship and are primarily used onboard ships to adjust one or more parameters of a system. The prime function of the controller is to maintain the parameter as per the required value set by the operator. These parameters could be anything including jacket water temperature, lubricating oil temperature, fuel oil pressure, and many more. PID controllers are dedicatedly used for all these applications. The main advantage of the automatic controller is that it controls and also indicates the parameter reading.
On and off action of a controller
If we consider the simplest form of control, then only two control positions (on and off) are allowed. In the case of a valve, it opens or closes by the signal from the controller. The common examples of such control system are; water level control for boiler tank, air compressor cut in cut off control, temperature control for fuel oil storage tanks, and many more. Now, let’s consider the case of a fuel oil tank heating steam. It comprises of a controller which relentlessly senses the system parameter (fuel oil temperature). This is known as the measured value. On the other hand, the desired value (temperature of fuel oil needs to be maintained) is fixed by the operator. If the temperature of the fuel oil drops below the setpoint, the controller will send a signal to the steam valve. This allows passing steam through coils. As a result, the temperature of fuel oil starts enhancing. When the temperature rises to the setpoint, the controller automatically shuts the steam valve.
Now, we all are well aware of thermal inertia in this system. Or we can say that the position of temperature sensor and that of the steam coil is different. This is the reason we can’t experience an increase in temperature very early when the steam valve opens. However, the prime disadvantage of this control is a major deviation from the desired value or set point.
In this continuous action, the controller’s output is proportional to the deviation between measured and desired value. An example is a simple water level controller.
Integral or reset action
This action is used along with proportional action. Here, controller output differs at a rate proportional to the deviation between measured and desired value.
Derivative or rate action
A derivative action is applied with the conjunction of proportional and integral actions. An example is temperature control for the jacket water system. Here, the controller output is proportional to the rate of change of deviation.
- Maker : SIBO
- Model : SB-NL
- Description : Signal Light Controller
- Maker : Fisher
- Type : C1
- Model No : 19008196
- Maker : Jumo
- Type : Dicon 400
- Description : Universal Process Controller
Ship Automation is an established company which deals with various types of ship controllers including Fisher C1 pneumatic controller, SIBO SB-NL controllers, and Jumbo diction 400. The company also offers various spare parts like ship automation system, marine automation system, and marine control system. Just visit the website of the company to know more about it and its products.