The typical electronic system comprises modules which are designed for mounting in the control room desk or in a cabinet front. Here are standard modules: alarm measuring module, display module, selector module, bridge panel, cabin and mess panel, power distribution unit, central unit for data logging and alarm print-out.
These modules are identical in electrical and mechanical design. The modules are made of sheet steel and are provided with ventilation holes. The internal wiring is provided with a printed circuit backplate, i. e. the "mother board", and ribbon cable. The front can be removed, and the electric boards can be inserted from the front.
Each module has a circuit board for stabilizing the supply voltage to the electronics. The modules are interconnected by ribbon cable — the system bus — used for internal communication in the system. Process signals and the power supply are connected to terminals at the rear of the module on the terminal board.
Alarm and measuring modules. They are designed with space for several analog or on/off channel boards. In front of each channel is a transparent legend plate on which the name of the channel is engraved, and a push-button for visual alarm acknowledgement and manual measuring.
The channel boards, which can be located in these modules according to the customer's requirements, are:
- On/off alarm board, for adapting the on/off transducer signals.
- Analog channel board, for adapting the analog transducer signal.
- Average board, for calculation of mean values.
- Group alarm board, for generation of group alarm signals.
- Blocking board, for adapting the blocking transducer signals of internal blocking signals.
Apart from the electronics for interfacing the display, the module includes circuits for generating start signals to the sirens and the rotating lights. The front is equipped with a push button for audible alarm acknowledgement.
Selector module. It is used for the selection of the engine room status, attended or unattended, and an engineer on duty. The module is equipped with one circuit board per engineer, and switches and indicating lamps in the front. The unit also provides call of the engineers.
Central unit. Systems with alarm print-out or data logging include the central unit. The control unit is connected to the system via the system bus.
Such systems are programmable bus-oriented electronic systems comprising a number of standard units. The functions in the system are controlled from a central processing unit based on a microcomputer.
The functions are determined by a program — the system software — stored on a PROM semi-conductor memory. In addition to the basic functions of the central unit the use of the microcomputer and software make such alarm systems easily expandable to more complex functions.
Typical optional functions available are: presentation of process data on a display, telex transmission of measured values, trend analyses, condition monitoring of the machinery.
The central unit is fitted in a cubicle. The front of the cubicle includes the printer for alarm print-out.
Data Logging
The data logging function is controlled from the control unit. The measured, values are printed out at regular intervals, e. g. every four hours, or by depressing the print-out button.
The central unit addresses the measuring channels with a binary code via the system bus. The address is decoded in each module and one channel is addressed. Signal connections to the system bus, scaling and conversion, are carried out in the same way as during manual measuring.
However, the display is extinguished. The central unit receives the measured value in code and the information on the number of decimals, processes the input signals and controls the typewriter, where the measured values are printed out. The data and time are recorded on each print-out.
An Alarm Measuring System on a vessel is a critical component of maritime safety, designed to monitor various parameters and provide alerts when readings fall outside predefined safe ranges. The system comprises several modules, each dedicated to monitoring specific aspects of the vessel’s operation and condition. Here are the key modules typically found in an Alarm Measuring System on a vessel:
1. Engine Monitoring Module
- Temperature Sensors: Monitor engine temperature to prevent overheating.
- Pressure Sensors: Track oil pressure, coolant pressure, and fuel pressure.
- RPM Sensors: Measure the revolutions per minute of the engine.
- Fuel Consumption Meters: Monitor fuel usage rates.
2. Electrical Systems Monitoring Module
- Voltage Sensors: Measure voltage levels of the electrical system and batteries.
- Current Sensors: Monitor current flow in various circuits.
- Power Consumption Meters: Track power usage across different systems.
3. Navigation Systems Monitoring Module
- GPS and AIS Systems: Provide location data and track nearby vessels.
- Gyrocompass: Monitor the vessel’s heading.
- Radar Systems: Track objects and obstacles in the vicinity.
4. Environmental Monitoring Module
- Bilge Water Sensors: Detect water levels in the bilge to prevent flooding.
- Fire Detection Systems: Monitor for signs of fire, such as smoke or heat.
- Gas Detectors: Measure levels of hazardous gases like CO2 or H2S.
5. Hull and Structural Monitoring Module
- Stress and Strain Gauges: Measure stress and strain on the hull and critical structural components.
- Vibration Sensors: Detect abnormal vibrations that could indicate structural issues.
6. Safety and Lifesaving Equipment Monitoring Module
- Lifeboat and Life Raft Status Sensors: Ensure that lifesaving equipment is properly maintained and ready for use.
- EPIRB (Emergency Position Indicating Radio Beacon): Monitor the status and readiness of the EPIRB.
7. Communication Systems Monitoring Module
- VHF and MF/HF Radios: Ensure communication systems are operational.
- Satellite Communication Systems: Monitor connectivity and functionality.
8. Cargo Monitoring Module (for cargo vessels)
- Cargo Hold Sensors: Measure temperature, humidity, and pressure in cargo holds.
- Tank Gauging Systems: Monitor the levels and conditions of liquid cargo.
9. Propulsion and Steering Systems Monitoring Module
- Propeller Shaft RPM Sensors: Monitor the speed of the propeller shaft.
- Rudder Angle Sensors: Track the angle of the rudder to ensure proper steering.
10. Bridge Alarm Systems
- Watch Alarm Systems: Ensure the watch officer is alert and awake.
- Bridge Navigational Watch Alarm System (BNWAS): Monitor bridge activity to alert the crew in case of inactivity.
Integration and Central Monitoring
All these modules are typically integrated into a central monitoring system, often located on the bridge, which provides a comprehensive overview of the vessel’s status. This system allows for real-time monitoring, data logging, and automated alerts to ensure the safety and operational efficiency of the vessel. The central system often includes:
- Alarm Display Units: Show real-time status and alerts.
- Control Panels: Allow crew to interact with and manage the alarm system.
- Data Loggers: Record historical data for analysis and reporting.
- Remote Monitoring Capabilities: Enable off-ship monitoring and support.
An Alarm Measuring System on a vessel is a multifaceted and highly integrated system designed to ensure the safety, efficiency, and operational readiness of the vessel. Each module plays a vital role in monitoring specific parameters and providing timely alerts to prevent accidents and ensure compliance with maritime regulations.
