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Orion Marine
Marine Electrical

Marine Switchboards & Power Distribution

New equipment needs a supply and the board has no spare way. A breaker is out of production and its successor is a different frame. A new transformer loads a feeder that was sized twenty years ago. We modify, extend and repair the distribution system the vessel already has.

Typical jobs

Four jobs that need more than a parts swap

A switchboard change affects the supply and protection downstream of it. Each change is checked against the board, the protection scheme and the upstream supply before it is fitted.

  1. 01

    No spare outgoing way

    New equipment needs a feeder and every way on the board is in use. Before adding a way, we check the physical space in the section, the busbar arrangement and rating, the breaker rating against the fault level, the protection settings and the cable size for the run. The final connection requires an isolated section, so the shutdown is planned into a port stay or docking.

  2. 02

    Replacing or adding a breaker

    The original breaker is no longer made, and the current model may have a different frame, terminals and trip unit. The replacement has to suit the available space and busbar arrangement, interrupt the prospective fault current at that point, and be set to grade with the protective devices above and below it.

  3. 03

    A new transformer or distribution board

    A refitted galley, new air-conditioning plant or treatment system may arrive with its own distribution board or transformer. The added load has to be checked against the feeder, the switchboard section supplying it and the available generator capacity in each operating mode. Transformer inrush is also allowed for in the feeder protection.

  4. 04

    A small fault trips too much of the vessel

    A fault on one consumer should be cleared by the device nearest to it. When a fault on a small feeder opens a bus-tie or a generator breaker instead, the protection is not selective. We compare the settings and curves of the devices in series, find where they overlap and correct it.

Engineering checks

What is checked before a board is modified

The fault level determines the interrupting capacity a breaker needs. It depends on the generators that can run in parallel, any transformers and the cable between the source and the board, so it changes across the distribution system. A breaker suitable at one board may not have the required interrupting capacity at another.

Selectivity decides how much of the vessel a fault takes with it. Each protective device has a time and current characteristic, and the characteristics of devices in series have to stay apart across the range of fault currents. When a breaker or a setting changes, the grading with its neighbours is checked again.

Then come the physical and operational constraints: space in the section, busbar capacity, cable route and the time the board can be isolated. Those answers determine whether the work is a new outgoing way during a port stay or a new section planned as a retrofit.

The distribution chain

From generation to final consumers

Power leaves the generators, is collected and distributed at the main switchboard, and reaches each consumer through feeders, transformers and distribution boards. The checks and work change at each point in that chain.

  1. 01

    Generators

    Incoming sections

    Generator breakers, their protection and the synchronising equipment on the incoming sections. The machines themselves are covered under generators, motors and drives.

  2. 02

    Main switchboard

    Busbars, bus-tie, outgoing ways

    Added and replaced breakers, new sections, busbar connections and bus-tie work. The same engineering checks apply to modifications on the emergency switchboard and its interconnections.

  3. 03

    Feeders and transformers

    The links to the rest of the ship

    New and re-rated feeders, step-down and isolation transformers, and the protection at each end. A shore connection arrives at the main switchboard as one more incoming feeder, with interlocking of its own.

  4. 04

    Distribution boards

    Local distribution

    Lighting, galley, accommodation and machinery distribution boards, extended, replaced or added, with outgoing circuits sized and protected for their loads.

  5. 05

    Consumers

    The final circuits

    The supply to each motor, heater or panel. From this point the work continues at the starter or the drive.

A change at any point is checked against the system upstream of it. A new consumer at the end of the chain also has to be checked against its distribution board, the feeder supplying that board and the available generation.

Timing

How switchboard work is planned around shutdowns

Switchboard modifications are planned around the section that has to be isolated and the time available to do the work.

  • Preparation and cable pulling while the vessel trades
  • Connection of a single way or feeder during a port stay
  • New sections and busbar work during a docking period
  • Fault repair when a board or a feeder has failed
Information

What helps us scope it

These details let us assess the likely scope before an onboard survey and identify what still has to be checked on the vessel.

  • Single-line diagram
  • Switchboard general arrangement and photos of the section
  • Breaker makes, types and settings
  • The new load: power, voltage and starting method
  • Electrical load analysis, if one is available
Related work

Related electrical work

FAQ

Before a switchboard modification

Can a feeder be added without shutting down the whole switchboard?
It depends on how the board is built and how it can be sectionalised. Where one section can be safely isolated, work may be possible with the rest of the board in service. Where it cannot, the shutdown is planned around the vessel's available alternative supply and operating requirements. We confirm the arrangement during the survey.
The original breaker is obsolete. Does the whole section have to be replaced?
Often not. A current breaker may be fitted with an engineered adaptation if its ratings, trip characteristics, physical arrangement and busbar connection suit that position. If the section itself is at the end of its service life, replacing the section may be the better use of the shutdown window.
Do switchboard modifications need class approval?
Some modifications do, depending on the scope, the affected services and the vessel's class requirements. Where approval is required, we prepare the relevant drawings and test records for submission and allow for review in the schedule.

Need to add a feeder or modify a switchboard?

Send the single-line diagram and the change required. We will identify what can be checked from the documents, what needs an onboard survey and what isolation window the connection is likely to need.