Page 304 - International safety guide for oil tankers and terminals

INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS

Earthing is achieved by the establishment of an electrically continuous low resistance
path between a conducting body and the general mass of the earth. Earthing may
---ใช้เพื่อการศึกษาเท่านั้น---
occur inherently through intimate contact with the ground or water, or it may be
provided deliberately by means of an electrical connection between the body and the
ground.
their characteristics must conform to the national standards in the country concerned,ย์นาวี
Bonding occurs where a suitable electrically continuous path is established between
conducting bodies. Bonding may be achieved between two or more bodies without
involving earthing, but more commonly earthing gives rise to bonding with the general
mass of the earth acting as the electrical connection. Bonding may arise by
construction through the bolting together of metallic bodies, thus affording electrical
continuity, or may be by the provision of an additional bonding conductor between
them.
งานห้องสมุด ศูนย์ฝกพาณิช
Most earthing and bonding devices intended to protect against electrical faults or
lightning are permanently installed parts of the equipment which they protect, and

or to classification societies’ rules, where relevant.

The acceptable resistance in the earthing system depends upon the type of hazard
that it is required to guard against. To protect electrical systems and equipment, the
resistance value is chosen so as to ensure the correct operation of the protective
device (e.g. cut out or fuse) in the electrical circuit. For lightning protection, the value
depends on national regulations, and is typically in the range of 5-25 ohms.
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270 © ICS/OCIMF/IAPH 2006