A marine transformer is a shore transformer with a harder life. The electrical design is broadly the same; what changes is everything around it. This article sets out the requirements that actually drive the design, and the documentation buyers should expect.
Vibration and shock
Machinery, propellers and hull movement produce continuous vibration, and heavy seas produce shock loading. The core and coil assembly has to be clamped so it cannot work loose, and the clamping has to stay effective over the life of the vessel. Windings are braced and impregnated or cast so that conductor movement is prevented. Mounting feet are dimensioned for shipboard foundation practice, and resilient mounts are used where noise limits apply.
Humidity and salt spray
Salt laden air is the defining problem. It attacks windings, terminations, fasteners and painted surfaces. The responses are insulation systems that resist moisture ingress — cast resin or vacuum pressure impregnated windings rather than open construction — corrosion resistant fixings, sealed enclosures with appropriate gasket materials, and coating systems specified for marine exposure. Drainage and ventilation details matter too: an enclosure that traps moist, salty air will fail regardless of what the paint specification says.
Operation at inclination
A vessel heels and trims, and equipment has to keep working while it does. Cooling air paths must remain effective at the specified angles of inclination, and oil immersed designs must keep critical parts covered. The applicable inclination limits come from the classification rules or the vessel specification and should be stated on the enquiry.
Restricted space
Space on board is expensive, and transformer rooms are rarely generous. That pushes designs towards compact construction, cable entry from specific directions, and layouts that allow maintenance access from the front only. Dimensions and termination positions are usually fixed by the shipyard drawing rather than chosen by the manufacturer.
Noise
Noise limits are tightest near accommodation spaces. The levers are flux density in the core, core construction and clamping, resilient mounting, and enclosure treatment. This has to be settled at specification stage — retrofitting acoustic treatment into a finished accommodation area is far more expensive than designing for it.
Voltage and frequency
Shipboard systems vary with the vessel design, and 60 Hz is common. Ratings, vector group and enclosure are built to the distribution system you specify rather than to one domestic standard.
Fire and safety
This is the main reason dry type and cast resin construction dominates on board. With no oil there is no fire load and no requirement for a containment pit or a fire rated enclosure, which matters in a hull where escape routes are constrained. Where oil immersed units are used, containment and fire suppression requirements apply.
Classification and documentation
Where a project requires classification society review, the documentation package typically includes drawings, calculations, material certificates, test reports and inspection records. We support the documentation, inspection and witness testing process for the society named in your specification, and we state plainly which approvals we hold and which would be obtained for the project.
Testing before dispatch
Every unit receives routine testing — winding resistance, ratio and vector group, impedance and load loss, no load loss and current, applied and induced voltage withstand, and insulation resistance — with measured values recorded on the test sheet that ships with the unit. Type test evidence is arranged where the specification requires it.