2 Terms
2.0.1 Petrochemical plant
A process plant where crude，natural gas and its intermediate products are used as feedstocks to produce petrochemical products（or intermediates）.
2.0.2 Support facilities
Facilities necessary for supporting main process plant to complete production process，including tank farm，central lab，wastewater treatment plant，maintenance workshop，flare and so on.
2.0.3 Industrial building
A production（storage）building that is provided with roof and its exterior enclosure structure is all constructed by enclosed walls（including doors and windows）.
2.0.4 Outdoor unit
A location that is sited in open air or is open to air to have good air ventilation.
2.0.5 Semi-enclosed industrial building
A production building that is provided with roof，its exterior enclosure structure is partially constructed by walls，and the area occupied by walls does not exceed 1/3 of the surface area of exterior enclosure structure（excluding the roof area and grade area）.
2.0.6 Opened industrial building
A production building that is provided with roof，but not provided with exterior enclosure structure.
2.0.7 Lightning stroke
Single electrical discharge in a lightning flash to earth.
2.0.8 Direct lightning flash
A lightning flash that directly strikes building，other object，earth or external lightning protection system and generates electric effect，thermal effect and mechanical force.
2.0.9 Lightning induction Lightning electrostatic induction and lightning electromagnetic induction due to spark discharge between metal components of adjacent conductors in case of lightning discharge.
2.0.10 Lightning surge on incoming services
Lightning wave，i.e.，lightning surge that may intrude into the building along overhead power lines，cables or metalpipes，and endanger personnel safety or damage equipment due to lightning effect to such facilities.
2.0.11 Lightning protection system（LPS）
A complete system used to reduce physical damage due to lightning stroke to process plant，which consists of both external and internal lightning protection system.
2.0.12 External lightning protection system
A part of lightning protection system consists of an air-termination system，a down-conductor system and an earth-termination system.
2.0.13 Internal lightning protection system
Apart of lightning protection system consists of lightning equipotential bonding and/or electrical insulation of external lightning protection system.
2.0.14 Air-termination system
Apart of an external lightning protection system using metallic elements such as rods，mesh conductors or catenary wires intended to intercept lightning flashes.
2.0.15 Down-conductor system
A part of external lightning protection system intended to conduct lightning current from the airtermination system to the earth-termination system.
2.0.16 Earth-termination system
A part of external lightning protection system which is intended to conduct and disperse lightning current into the earth.
2.0.17 Earth electrode
A part or a group of parts of the earth-termination system which provides direct electrical contact with the earth and disperses lightning current to the earth.
2.0.18 Earth conductor
A bonding connector from the test joint or splicer of down-conductor system to earth electrode，or from earth terminal，bonding bar to earth electrode or earth-termination system.
2.0.19 Bonding network
Interconnecting network of all conductive parts of the structure and of internal systems（live conductors excluded）to the earth-termination system.
2.0.20 Earthing system
A complete system combining earth-termination system and bonding network.
2.0.21 Earth resistance
Sum of resistance-to-ground of earth electrode or natural earth electrode plus resistance of earth conductor.
2.0.22 Power frequency earth resistance
A resistance calculated per the power frequency alternating current that flows into grade through earth electrode.
2.0.23 Impulse earth resistance
A ground resistance calculated per the impulse current that flows into grade through earth electrode.