This manual deals with
those matters affecting onshore installations which differ from those of
offshore installations. All aspects of
offshore plant and systems are dealt with in detail in the other manuals of the
Electrical series, and many of them apply equally to onshore plant.
Areas where there are
notable differences between onshore and offshore practice are as follows:
(a) Power
supplies for onshore installations are taken from the National Grid and not
from local generators.
(b) Electrical
energy, taken from the grid in England and Wales through Area Electricity
Boards, but in Scotland, in the absence of separate Area Authorities, taken
direct from the grid, must be paid for under a tariff. On an offshore installation the energy comes
mainly from the installation’s own well-gas, which in tariff terms can be
regarded as ‘free’, whereas onshore it must be paid for.
(c) All
offshore staff live, sleep and eat on board, and full facilities must be
provided for personnel. Most onshore
staff live away from the station, and only limited living facilities need be
provided.
(d) Onshore
installations do not have the heavy electrical loads associated with drilling
and well processes such as water injection, gas injection and mud pumping.
(e) Offshore
installations require heckling facilities, marine/air radio communications,
navigation aids, lifeboats and similar services, none of which is needed
onshore.
(f) Because
of tariff requirements there is need onshore for power-factor control and, if
necessary, power-factor correction.
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