Ports and Shipbuilding

How ports and shipyards draw power

Power use in ports and shipbuilding areas concentrates in handling machinery, dry docks and outfitting shops: ship-to-shore and gantry cranes, winches and heavy welding plant start and stop constantly, the load curve swings sharply, and inrush currents with repeated short-time overloads are normal. Work follows the shipping schedule around the clock, and supply points move with the berth or the building dock.

These sites also sit in a marine environment, with high humidity, salt fog and dust or oil mist settling on the equipment. Switchgear often stands at the quay edge, inside workshop bays or at temporary supply points, so requirements for moisture, salt-fog and corrosion protection and for flame retardance are higher than inland.

What ports and shipyards have to cope with

Equipment on a coastal site faces two pressures at once: sharp electrical variation, and steady environmental attack.

• Lifting and welding loads that start and stop constantly, with repeated short-time overloads and inrush currents
• Salt fog, humidity and dust accelerating corrosion of metalwork and degradation of insulation
• High fire-protection requirements in workshops and docks, with no toxic gas released if equipment burns
• Supply points that move with the production sequence, so assemblies must be easy to extend and rearrange
• Numerous motor circuits calling for centralised control and quick replacement

The right answer here is a dry-type transformer that tolerates moisture, corrosion and overload, together with withdrawable assemblies whose structure has been treated against corrosion.

Coreda's approach for ports and shipyards

We build around non-encapsulated class H transformers, which contain no combustible resin, and epoxy cast-resin dry-type units, with withdrawable LV cubicles organising the motor and feeder circuits.

Recommended configuration:

• Class H non-encapsulated dry-type transformer: Nomex® winding insulation (class C, usable continuously at 220 °C) with the transformer rated class H (180 °C), capable of 20% continuous overload without forced cooling, suited to damp environments and widely varying loads.
• 10 kV SC(B)11–SC(B)18 epoxy cast-resin dry-type transformer: windings that do not absorb moisture and can operate at 100% relative humidity, core clamps with an anti-corrosion coating, and an enclosure in IP20 or IP23 for outdoor duty.
• GCK withdrawable LV switchgear: metal parts galvanised or powder-coated, main busbar, functional-unit and cable compartments separated, usable for PC and MCC duties, with mechanical interlocks and anti-drop devices on the drawers.

For open-air positions choose the IP23 enclosure and allow for derating: an IP23 enclosure reduces the cooling capacity of the transformer by about 5% on small ratings and about 10% on large ones.