MIL-HDBK-1025/10
outlet assemblies. The safety requirements for the pier electrical outlet assemblies which supply
line side components are covered by earlier sections. However since they are provided for ships
power in addition to permanent pier electrical loads they are described for a clearer understanding
of the dockside electrical distribution system.
9.2.1 Shore Medium-Voltage Distribution System. The facility's primary electrical
distribution system normally operates in the medium-voltage range between 5 kV and 35 kV. For
permanent pier service dual primary feeders from the shore's primary system is preferred. Pier
systems may also be furnished with single feeders. These feeders serve substations which
stepdown the distribution system's primary voltage to the required secondary voltage for ships
electrical service of either 4.16 kV or 480 volts.
9.2.2 Pier Substations. Substations may consist of above ground substations of the
nonfixed type installed on the top of a pier or units of the fixed type installed in vaults located
under the pier. Fixed substations are fed by primary cables installed in duct lines. Nonfixed
substations are skid-mounted and fed from a shore installation substation consisting of a medium-
voltage disconnect assembly. Nonfixed substations are supplied by primary cable assemblies
installed on the pier and are connected to the electrical distribution system source and the
substation by primary voltage pier coupler plugs and receptacles in electrical connection outlet
assemblies. Both types of substations contain primary switch(es), the step-down transformer, and
secondary circuit breakers supplying the pier electrical outlet assemblies for ship-to-shore power
cables. Pictures A, B, C, and D show these component elements.
9.2.3 Ship-to-Shore Pier Electrical Outlet Assemblies. Ships service is from pier
electrical outlet assemblies which contain multiples of three-pole, 500-ampere receptacles rated
either for 450-volts ships service or 4.16-kV ships service as appropriate to the pier's ship
electrical service requirement. Receptacles are interlocked with their associated substation
secondary circuit breaker for safety reasons. Pictures E and F show outlet assemblies for 480-volt
and 4.16-kV services respectively.
9.2.4 Ship-to-Shore Power Cables And Connectors. Portable shore-to-ship power
cables are rated for operating at either medium voltage (rated at 601 to 5000 volts, three-phase,
three-wire, ac) or low voltage (450 volt, three phase, three-wire ac). All shore-to-ship power
circuits operate ungrounded between the shore enclosure and the ship.
Note
Splices are not allowed in 4.16-kV power cables. Pictures G, H, I, and J
show examples of cables in place and various connections.
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