Instrument earthing system shall consist of the following earth type:Electrical earthing (also called dirty earthing or Protective Earthing(PE)Instrument earthing (also called Reference Earth (RE))Intrinsically safe earthingElectrical earthing:Electrical earthing is used to protect the power system, electrical equipment, and persoel from electric shock.How to do an electrical earthing?Armor of field instrument cable shall be terminated at cable gland.Armor of single and multi-core cable going to junction box shall be terminated at cable gland. If the junction box made from metal, then it only needs to coect the earth stud bolt to the nearest steel structure. If the junction box made from non-metal, the earth stud bolt will be located at the metal gland plates which have direct contact with the cable gland.Armor of single and multi-core cable going inside or outside marshalling and system cabinet shall be terminated and coected to a bus bar inside the cabinet. Each bus bar inside the cabinet will be coected to a grounding dispatcher by 35 mm2 cable (usually green-yellow stripped). This grounding dispatcher will collect all coection from individual bus bar and then coect it to a general electrical earth loop (to structure steel) by a 70 mm7 cable. In general used, the earth bus bar is made from copper and has 1 ½” width and ¼” height.Instrument earth:The general principle of instrument earth is all individual shields (screen) and overall shield (screen) of single
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نویسنده: مانی کاظمیان
تاريخ: چهارشنبه
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1402 ساعت: 7:19