Practical Marine Electrical Knowledge: Program 1. Ships Electrical Systems - Safety and Maintenance

Introduction to Marine Electrical Systems

Overview of Program 1

• This program is part of the VIDEOTEL series on practical marine electrical knowledge, consisting of seven programs.

• It introduces a typical 440 volt AC marine electrical system, first-aid rescue procedures, test instruments, and preventive maintenance.

• Emphasizes the importance of familiarizing oneself with the main switchboard components upon joining a ship, especially during emergencies.

Electrical Safety Protocols

Importance of Safety Measures

• The Golden Rule: Always isolate the circuit before any work by removing supply fuses or locking circuit-breakers in the open position.

• Post warning signs to alert others that work is being conducted on the circuit. Prove the circuit dead using a voltmeter or approved line tester.

• A switchboard can only be considered dead when all connected alternators are stopped and locked off, along with disconnection from other supplies.

International Safety Standards

Compliance Requirements

• All ships' electrical systems must meet international safety standards as per the International Convention for Safety Of Life At Sea (SOLAS) 1974 and its amendments.

• Ships are issued safety certificates according to these conventions, ensuring compliance with various codes published by the International Maritime Organization (IMO).

• Practical guidance for electrical installation and maintenance is provided by rules from the International Electrotechnical Commission (IEC). These guidelines apply universally to onboard electrical systems.

Understanding Marine Electrical Components

Key Components Identified

• Introduction to essential components in a typical marine electrical system: AC generators/alternators, switchboards, busbars, circuit-breakers, switches, fuses.

• Additional components include transformers, motors, and various instruments such as voltmeters and ammeters used for monitoring power metrics onboard ships.

Power Supply Mechanisms

Power Generation and Backup Systems

• Generated power typically comes from one or more main alternators and auxiliary/standby alternators based on vessel power needs; at least one should be diesel-driven.

• In case of normal power failure, an emergency diesel alternator activates automatically or manually to maintain essential services onboard ship.

Shore Power Connection Procedures

Connecting Shore Power

• During drydock periods, mains power may be supplied from shore through connections at either main or emergency switchboards via circuit-breakers or separate connection boxes near deck areas.

• Shore connection boxes usually feature voltmeters and phase sequence indicators for monitoring purposes while ensuring minimum lighting and alarm systems remain operational during emergencies through battery supplies.

Main Switchboard Functionality

Distribution System Overview

• The heart of a ship's electrical distribution system is its main switchboard where generated power connects via alternator circuit breakers to busbars .

• Each alternator has dedicated panels allowing them to connect separately or in parallel; synchronizing panels facilitate auto/manual synchronization with necessary controls like synchroscopes .

Emergency Power Systems and Safety Procedures

Overview of Emergency Power Systems

• The battery charger maintains emergency batteries during normal conditions, ensuring readiness for power failures.

• The emergency switchboard, smaller than the main switchboard, is supplied by the main board through a circuit-breaker and operates independently via its own alternator when mains power fails.

• This system powers essential services including firefighting pumps, steering gear motors, navigation aids, and approximately 30% of the ship's lighting.

Importance of Electrical Safety

• Electricity poses significant dangers; fatal shocks can occur at voltages as low as 50 volts. Understanding safety regulations is crucial for all personnel.

• Familiarity with rescue methods related to electric shock is vital: first step is to switch off the supply if possible before attempting any rescue actions.

Rescue Procedures in Case of Electric Shock

• Key steps include:

• Isolate the electrical supply if feasible.

• Safely remove the victim from contact with electricity.

• Check pupils for dilation; dilated pupils may indicate cardiac arrest requiring immediate action.

• Administer external cardiac massage and rhythmic lung inflation until consciousness returns or medical help arrives. Ensure to turn the victim on their side post-rescue to prevent choking if vomiting occurs.

Test Instruments for Electrical Fault Finding

• The use of test instruments is critical in diagnosing electrical faults; they must be tested prior to use for reliability. Common tools include multimeters, insulation resistance testers, and line testers.

Multimeter Setup Procedures

• Analog Multimeter:

• Set dials appropriately for AC current measurement (e.g., AC system selection and value range). For DC measurements, adjust settings accordingly.

• Resistance testing requires setting one dial to ohmic system while selecting ranges with another dial; zeroing out before testing is necessary.

• Digital Multimeter:

• Displays values numerically rather than via a pointer; includes various scales such as DC volts/amps and AC volts/amps.

• Overload condition indicated by "OL" when no measurable load exists within set range; ensure proper settings are canceled after use.

Insulation Resistance Tester Usage

• Used for monitoring onboard electrical circuitry conditions and fault tracing.

Understanding Electrical Maintenance on Ships

Importance of Testing Instruments

• A line tester is utilized to check for the presence of 220 volts in electrical systems. Proper setup and function testing of these instruments are crucial for accurate monitoring.

Condition Monitoring and Preventive Maintenance

• The electrical systems on ships experience wear due to environmental factors such as temperature changes, humidity, and vibration. Continuous condition monitoring is essential to maintain system integrity.

• Preventive maintenance strategies often rely on insulation resistance trends and vibration monitoring, which help in planning maintenance activities effectively.

Vibration Monitoring Practices

• Regular vibration monitoring is conducted using various methods; results are meticulously recorded for future analysis to identify potential issues before they escalate into costly repairs.

Maintenance Protocols

• All maintenance should follow a prepared job sheet, especially for high voltage systems, adhering strictly to an approved permit-to-work system to ensure safety.

Summary of Program Insights

• The program provided an overview of a typical ship's electrical system, including graphic symbols used in the field. It emphasized safety procedures and modern preventive maintenance approaches.