With reference to shore supplies:
(a) state THREE necessary parameters that must be checked before connecting to the vessel’s distribution system;(3)
(b) explain the possible consequences of connecting an incorrect shore supply.(7)
Question 9.
Several mention the parameters and then totally ignore them in part b. Many state what will occur but not the consequences eg high current but not explaining that this will cause overheating and damage.
What are shore supplies?
In the maritime context, shore supplies refer to the various utilities and services provided to a vessel while it is docked or moored in a port or harbor. These supplies are essential for the vessel’s operation, maintenance, and crew’s well-being while in port.
The most common shore supplies include:
- Electrical Power (Shore Power):
- Purpose: Provides electricity to the vessel, allowing it to shut down its own generators and reduce emissions, noise, and fuel consumption while in port. 1. Power in port – Bureau Veritas Marine & Offshore marine-offshore.bureauveritas.com
- Connection: Typically supplied through a high-voltage cable connected to a dedicated shore power connection point on the vessel.
- Requirements: The voltage and frequency of the shore power must match the vessel’s electrical system, and proper safety measures like isolation and grounding must be in place. 1. Shore connection: improving ship efficiency and cutting harborside emissions – ABB Group new.abb.com
- Fresh Water:
- Purpose: Replenishes the vessel’s freshwater tanks for drinking, cooking, washing, and other onboard uses.
- Connection: Supplied through hoses connected to the ship’s freshwater filling points.
- Quality: The water quality must meet potable water standards to ensure it’s safe for consumption.
- Fuel Oil (Bunkering):
- Purpose: Refuels the vessel’s fuel tanks for propulsion and power generation.
- Connection: Delivered through specialized bunker barges or pipelines connected to the ship’s fuel manifolds.
- Safety: Bunkering operations require strict safety protocols to prevent spills and fire hazards. 1. What are The Safety Measures Prior to Bunkering – Indonesia Trusted Ship Agency balancia.co.id
- Lubricating Oil:
- Purpose: Replenishes the lubricating oil for the main engines, generators, and other machinery.
- Delivery: Usually delivered in drums or bulk containers and transferred to the vessel’s storage tanks.
- Sewage Removal:
- Purpose: Removes wastewater and sewage from the vessel’s holding tanks.
- Connection: Pumped out through a connection to a shore-based sewage reception facility.
- Garbage Disposal:
- Purpose: Disposes of the vessel’s garbage and waste.
- Collection: Garbage is typically collected in containers and taken ashore for disposal.
- Other Supplies:
- Provisions: Food, beverages, and other supplies for the crew and passengers.
- Technical Stores: Spare parts, tools, and other equipment for maintenance and repairs.
- Communication Services: Internet, telephone, and other communication services.
Importance of Shore Supplies:
- Operational Needs: They are vital for meeting the vessel’s operational needs while in port, such as power, water, and fuel.
- Maintenance and Repairs: Enable maintenance and repair activities by providing necessary supplies and services.
- Crew Welfare: Ensure the crew’s well-being by providing access to fresh water, food, and other essentials.
- Environmental Protection: Proper management of waste and sewage disposal helps protect the marine environment.
Challenges and Considerations:
- Availability and Compatibility: Shore supplies might not be available or compatible with the vessel’s systems in all ports, requiring careful planning and coordination.
- Safety and Regulations: Various safety regulations and procedures govern the provision and handling of shore supplies to prevent accidents, pollution, and other risks.
In summary, shore supplies are essential for the operation, maintenance, and well-being of a vessel while in port. They encompass a range of utilities and services that enable the ship to function effectively, support the crew, and minimize environmental impact.
Necessary parameters that must be checked before connecting to the vessel’s distribution system.
Before connecting shore power to a vessel’s distribution system, it’s imperative to verify several critical parameters to ensure a safe and successful connection. Mismatched parameters can lead to severe damage to both the ship’s electrical system and the shore supply equipment. Here are the essential checks:
- Voltage:
- Match Voltage Levels: The voltage of the shore supply must match the voltage rating of the vessel’s electrical system. This is typically 400V or 440V for three-phase systems, but it can vary depending on the vessel’s design and the region’s electrical standards.
- Tolerance: A small tolerance (usually around ±10%) might be acceptable, but any significant mismatch can cause damage to equipment or trip protective devices.
- Frequency:
- Frequency Matching: The frequency of the shore supply must also match the vessel’s system frequency. This is usually 50Hz or 60Hz, again depending on the region and vessel specifications.
- Synchronization: If the vessel’s generators are running in parallel with the shore power, their frequencies must be synchronized before connecting the shore supply.
- Phase Sequence:
- Correct Phase Rotation: For three-phase systems, ensure the phase sequence (the order in which the phases reach their peak voltage) of the shore supply matches that of the vessel’s system. A phase sequence mismatch can cause motors to run in the wrong direction or damage electrical equipment. 1. What is a Phase Reversal fault? How do I protect my equipment? – Broyce Control broycecontrol.com
- Phase Sequence Indicator: Use a phase sequence indicator or meter to verify the phase sequence before connecting.
- Protective Devices:
- Circuit Breakers and Fuses: Ensure that the shore power connection has appropriate circuit breakers or fuses on its side to protect against overcurrents and short circuits.
- Earth Leakage Protection: Verify that the shore supply has earth leakage protection (ELCB or RCD) to safeguard against electric shock hazards.
- Grounding (Earthing):
- Proper Grounding: Establish a secure and reliable grounding connection between the vessel’s hull and the shore earth to provide a safe path for fault currents in case of an earth fault.
- Check Continuity: Verify the continuity of the grounding connection using a multimeter or other suitable testing equipment.
- Power Capacity:
- Shore Supply Capacity: Confirm that the shore power supply has sufficient capacity to handle the vessel’s load demand.
- Load Management: If necessary, adjust the vessel’s load to ensure it doesn’t exceed the shore supply’s capacity.
- Communication and Coordination:
- Clear Communication: Establish clear communication between the vessel’s crew and the shore power provider to confirm the parameters and ensure a safe connection.
Additional Checks (Depending on the System):
- Power Factor: In some cases, the power factor of the shore supply and the vessel’s system might need to be checked for compatibility.
- Harmonics: If the vessel has sensitive electronic equipment, it might be necessary to assess the harmonic content of the shore supply to ensure it’s within acceptable limits.
Safety Precautions:
- Qualified Personnel: Only qualified electricians or technicians should handle the connection and testing of shore power.
- Protective Equipment: Wear appropriate PPE, including insulated gloves and safety glasses.
- Visual Inspection: Visually inspect the shore power cable and connection points for any signs of damage or wear before connecting.
By carefully checking these parameters and following safety procedures, you can ensure a safe and successful connection to the shore power supply, avoiding potential damage to the vessel’s electrical system and ensuring a reliable power source while in port.
Possible consequences of connecting an incorrect shore supply
Connecting an incorrect shore supply to a vessel’s electrical system can have a cascade of disastrous consequences, impacting both the ship’s equipment and the safety of personnel on board. Let’s delve into the specific problems that can arise:
1. Voltage Mismatch:
- Overvoltage: If the shore supply voltage is significantly higher than the vessel’s rated voltage, it can lead to:
- Insulation Breakdown: The excessive voltage can stress the insulation of electrical components, causing it to break down and lead to short circuits or arcing.
- Overheating and Equipment Damage: Electrical equipment, such as motors, transformers, and electronics, might draw excessive current and overheat, leading to permanent damage or even fire.
- Lamp Burnout: Lights and other devices designed for a lower voltage will burn out quickly.
- Undervoltage: If the shore supply voltage is considerably lower than the vessel’s rated voltage, it can result in:
- Motor Stalling and Overheating: Motors might not start or run at their intended speed, leading to stalling, overheating, and potential damage.
- Reduced Performance: Electrical equipment might not function correctly or efficiently due to the lower voltage.
2. Frequency Mismatch:
- Motors and Generators: The most significant impact is on AC motors and generators.
- Overheating: A higher frequency from the shore supply will cause motors to run faster than their rated speed, leading to overheating and potential damage.
- Reduced Torque and Performance: A lower frequency will cause motors to run slower, reducing their torque output and affecting their ability to drive loads.
- Generator Issues: If the vessel’s generators are running in parallel with the shore supply, a frequency mismatch can cause instability, leading to potential damage to the generators and the electrical system.
3. Phase Sequence Mismatch:
- Reverse Rotation: In three-phase systems, an incorrect phase sequence will cause motors to rotate in the opposite direction, potentially damaging the connected machinery or equipment. 1. What is a Phase Reversal fault? How do I protect my equipment? – Broyce Control broycecontrol.com
- Operational Issues: Certain equipment might not function correctly or at all with the wrong phase sequence.
4. Other Issues:
- Earth Faults and Electric Shock: Improper grounding or faults in the shore supply can lead to earth faults on the vessel, creating electric shock hazards for personnel.
- Overcurrent and Circuit Breaker Tripping: If the shore supply’s current capacity is insufficient for the vessel’s load, it can cause overcurrent and trip the circuit breakers, leading to power interruptions.
Safety Precautions to Prevent Incorrect Connection:
- Verification of Parameters: Carefully check and verify the voltage, frequency, and phase sequence of the shore supply before connecting it to the vessel’s system.
- Use of Interlocks: Employ interlocks that prevent the shore power connection if the parameters are not within acceptable limits.
- Qualified Personnel: Only qualified electricians or technicians should handle the connection and testing of shore power.
- Communication: Establish clear communication with the shore power provider to confirm the supply parameters and ensure a safe connection.
Conclusion:
Connecting an incorrect shore supply can have devastating consequences, from equipment damage and malfunctions to fire hazards and electric shock risks. By diligently checking the parameters, using appropriate safety measures, and following proper procedures, you can ensure a safe and successful shore power connection and protect the vessel’s electrical system and personnel on board.