A ship always has hazards around her while she sails across the sea. Most of these dangers belong to the troubling waters and the weather conditions outside. Heavy weather overhead and lightning are a big part of these elements too. Hence, it is critical to understand how ships are protected from Lightning incidents.
Electrical Outbreaks
Many risks originate from such incidents of loose electrical outbreaks of any nature. However, lightning is not the only electrical hazard present for ships to deal with. Many short circuit incidents prove to be life-taking for seagoing vessels every year.
More than 1,200 electrical accidents and incidents of major and minor nature occur every year. Under such conditions, the ship’s earthing systems installations become essential for every size of the vessel. Such systems protect the internal electrical hazards and any external electrical risks too.
The article explains how modern-day ships exhibit their ability to deal with Lightning incidents. It also includes their earthing design and how the neutral system works onboard. We also identify the probable risks if such incidents or the current breaks happen too often.
Working Of Ships Earthing System
The purpose of an Earthing connection on the electrical systems is to handle the flow of leaking current. Any waste charge flows through these connections, saving the equipment and the lines. It resolves the possible hazards that come from such an outbreak.
A current break or leak can occur from different sources, a few of which include:
- A glitch or cut in the wire or transmission lines leads to electrical leaks
- A piece of faulty equipment such as a broken motor winding
- A fault in the circuit breakers or the electrical panel leads to a major current surge
Nature of Design
Cargo and Passenger ship’s earthing systems are insulated neutral, in contrast to the land designs of earthing neutral. It means that the neutral does not have direct tapping to the earth and has an insulating nature.
Hence, there is no direct pathway for the leaking current to flow to the earth. Despite this, ships adopt the insulated neutral design because of their critical operations.
On land, a single earth fault of a severe kind can cause the equipment to trip. It happens because the earthing connection allows a simple route for the current to flow, leading to a surge.
However, ships do not want their essential machinery to stop working under critical situations. Such lapses will lead to loss of propulsion, electrical power supply, or other incidents. These faults lead to navigation accidents and loss of cargo operations under serious situations.
Earth Fault Monitoring
A trip will happen when there is another earth fault across the other line, leading to interference. The two separate faults across phases cause the current flow to interfere in a hazardous manner.
Moreover, the higher number of machinery within a ship gives rise to more possibilities of earth faults. However, a short circuit is critical and does not usually occur because of the monitoring systems.
The monitoring system indicates the magnitude of the earth fault for an initial idea. It helps the engineers on board to detect and isolate the faulty line and the equipment.
While the zones or equipment are not detectable, step-wise fault-finding allows corrections. The indicating needle moves between 0 to infinity, depending on the occurrence of the fault. Hence, the earth fault correction and repairs take place to prevent any accidental trip.
Possible Risks
In the event of breakages within ships’ earthing systems, many risks loom large. The most severe situations coming from the possible earth fault and trips will be:
Fire Hazards
These can be from the possible sparks that result from the wires or the loose connections. Moreover, the overheating of systems before the equipment trip can result in fires too.
Fires are the scariest of shipboard risks due to their engulfing nature. The critical elements onboard do not have any other means of substitution. Once these systems catch fire, the total loss of ship control and accidents become inevitable.
Life Threat
A fault in the earthing system creates a live nature of the current passage. It means any contact with the naked limb will give an easy way to current.
The current creates a shock leading to cardiac arrest or permanent damage to the body part. Almost 1400 incidents of varying nature of electrical shocks occur on ships every year.
Lightning Protection of Ships
To understand how ships are protected from lightning, the probable effects are equally important. It includes the understanding of the nature of lightning bolts and how they disturb the vessels. Moreover, the possible outcome of these lightning strikes and their hazards are equally important.
Lightning at Sea
The lightning and thunder at sea need a path of movement like on land. During storms, the clouds have a changing polarization within themselves. It leads to the separation of charges, with the electrons at the bottom half.
These negative charges are ready to combine with the positive polarity of the land surface. Hence, a lightning bolt comes out as a way of dissipation of this energy into the Earth.
These thunderbolts look for an easy way out at sea for the flow of this charge too. It means any conducting surface present above the water will provide lighting with an easy way out.
Ships as Conductors
Since the current seeks the best and shortest route to ground, the conductors come into play. The nature of the charges to find the best way amplifies in the presence of such bodies. Hence, the floating ships with an all-metal design become the perfect conductor.
Lightning Protection Equipment Requirements
The lightning protection system onboard a vessel contains multiple layers of protection equipment. These elements play different roles in the overall safety protection of a ship against lightning.
Direct Strike Protection
The damages and impact of a direct lightning strike are the sources of lightning hazards. Hence, the protection system needs to mitigate the bolts while contacting the ship’s surface. Moreover, the system needs to move the lightning at one point instead to protect the other areas too.
Surge Protection
A surge in the voltage causes critical components of the vessel operation system to become ineffective. Hence, the lightning protection setup needs to account for surge protection with the bonding arrangement. It also includes the diversion of the lightning strikes to a safe zone onboard for further handling.
Flashing Safety
The side risk of a lightning incident onboard is the arc flashes on the systems. These will instantly lead to fires or blasts in the nearby area, causing fatalities and losses. Hence, direct bonding arrangements for all the equipment to a common point becomes essential.
Life Protection
The dissipation of lightning into the hull will impact the people on board with immediate shock. These shocks will range up to several thousand volts, immediately killing everything in sight. Hence, proper grounding arrangements for all the accommodation and other spaces take care of this hazard.
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Source: MarineInsight
