It's a flexible connection of some kind. In this drawing, it is likely to represent a trailing or reeling cable (I will explain this a bit more below.)

Supporting my claim - from AS1102.3 Graphical symbols for electrotechnical documentation - Part 103: Conductors and connecting devices, we have:

Note AS1102 is based on IEC 617 Graphical symbols for diagrams.

Contrast the symbol for a jumper ("connecting link"), also from AS1102.3, and a fuse, from AS1102.7.

What's a trailing cable?

A trailing or reeling cable is used to power mobile equipment, i.e. a mobile drilling rig, or mobile substation.

In this application, I think the 'sub-sea' transformer is in some kind of waterproof container, connected to the surface supply by trailing cables. Flexibility is required for the transformer to be moved around, or to move with the water currents.

Note that trailing cables are a special breed, not like regular cables. See Olex catalogue for trailing and reeling cables. Generally these cables are much more flexible than normal cables, are designed to withstand cars running over them, etc. There are also special protection features to detect if the cable has been damaged - these aren't required for normal cables which spend most of their life living in a protected environment, i.e. conduits.

Sadly there is no accepted standard. As with most schematics, whatever works to convey the information best for your group is all that matters.

Each tool is also going to implement hierarchical designs in different ways. Altium for example, allows you to add suffixes to reference designators. One way for you to do it would be to have R1_1, R1_2, R1_3 .. U1_1 U1_2 U1_3.

http://techdocs.altium.com/display/ADOH/Multi-Channel+Design+Concepts

It's a handy feature in theory but sacrifices the ability to set reference designators based on PCB placement which is much handier when you need to change out R1_2 but now have no idea where it is without searching your layout.