電氣成套設備的接地是保障系統運行、防止人身觸電及設備損壞的關鍵措施。其規范體系涵蓋材料選擇、安裝工藝、電阻要求及維護管理等多個環節,需嚴格遵循標準及行業規范。
The grounding of electrical equipment is a key measure to ensure the safe operation of the system, prevent personal electric shock and equipment damage. Its regulatory system covers multiple aspects such as material selection, installation process, resistance requirements, and maintenance management, and must strictly comply with national standards and industry norms.
一、必須接地的設備與范圍
1、 Equipment and scope that must be grounded
根據GB 50169-2016《電氣裝置安裝工程接地裝置施工及驗收規范》,以下設備必須可靠接地:
According to GB 50169-2016 "Code for Construction and Acceptance of Grounding Devices in Electrical Equipment Installation Engineering", the following equipment must be reliably grounded:
金屬外殼與框架:包括變壓器、電機、配電柜、控制屏等設備的金屬底座、外殼及傳動裝置。
Metal casing and frame: including metal bases, casings, and transmission devices for equipment such as transformers, motors, distribution cabinets, and control panels.
移動式設備:攜帶式或移動式用電器的金屬底座和外殼,如手持電動工具、移動式發電機。
Mobile devices: metal bases and casings for portable or mobile electrical appliances, such as handheld power tools and mobile generators.
電氣裝置構件:互感器二次繞組、電纜金屬外皮、金屬支架及靠近帶電體的金屬遮欄。
Electrical device components: secondary winding of transformer, metal sheath of cable, metal bracket, and metal fence near live parts.
特殊場景設備:儲存易燃易爆液體的儲罐、電弧爐外殼、高壓試驗設備等。
Special scenario equipment: storage tanks for flammable and explosive liquids, electric arc furnace casings, high-voltage testing equipment, etc.
例外情況:在木質或瀝青地面的干燥房間內,若交流電壓低于380V且直流電壓低于400V,設備外殼可不接地。
Exception: In a dry room with wooden or asphalt flooring, if the AC voltage is below 380V and the DC voltage is below 400V, the equipment casing may not be grounded.
二、接地材料與連接規范
2、 Grounding materials and connection specifications
材料選擇:
Material selection:
接地體:優先采用鍍鋅鋼管(直徑≥50mm,壁厚≥3.5mm)或角鋼(50mm×50mm×5mm),埋深0.5-0.8m以避開凍土層。
Grounding body: Galvanized steel pipes (diameter ≥ 50mm, wall thickness ≥ 3.5mm) or angle steels (50mm × 50mm × 5mm) should be preferred, with a burial depth of 0.5-0.8m to avoid frozen soil layers.
接地線:使用截面積≥25mm?的多股軟銅線,配備透明護套以識別損傷。
Grounding wire: Use multi strand soft copper wire with a cross-sectional area of ≥ 25mm ?, equipped with a transparent sheath to identify damage.
連接工藝:
Connection process:
禁止纏繞接地,需通過專用線夾或化學熔焊固定,確保接觸電阻≤0.1Ω。
It is prohibited to wrap the grounding, and it must be fixed with a dedicated wire clamp or chemical welding to ensure a contact resistance of ≤ 0.1 Ω.
銅質端子與設備外殼采用放熱熔焊,避免電化學腐蝕。
Copper terminals and equipment casings are welded using exothermic welding to avoid electrochemical corrosion.
扁鋼搭接長度≥寬度的2倍(少3個棱邊焊接),圓鋼搭接長度≥直徑的6倍。
Flat steel lap length ≥ 2 times the width (at least 3 edges welded), round steel lap length ≥ 6 times the diameter.
三、接地電阻要求
3、 Grounding resistance requirements
不同設備對接地電阻的限值差異顯著:
There are significant differences in the limit values of grounding resistance among different devices
防雷接地:獨立避雷針≤10Ω,共用接地體≤1Ω。
Lightning protection grounding: Independent lightning rod ≤ 10 Ω, shared grounding body ≤ 1 Ω.
保護:低壓設備≤4Ω,高壓設備≤0.5Ω(大接地電流系統)。
Safety protection: Low voltage equipment ≤ 4 Ω, high voltage equipment ≤ 0.5 Ω (high grounding current system).
防靜電:電子設備≤100Ω,油氣儲罐≤30Ω。
Anti static: Electronic devices ≤ 100 Ω, oil and gas storage tanks ≤ 30 Ω.
特殊場景:電弧爐外殼≤4Ω,獨立避雷針≤10Ω。
Special scenario: Electric arc furnace shell ≤ 4 Ω, independent lightning rod ≤ 10 Ω.
四、特殊環境適配要求
4、 Special environmental adaptation requirements
腐蝕性環境:采用鍍鋅鋼材或不銹鋼接地體,土壤電阻率過高時摻入木炭、降阻劑。
Corrosive environment: Galvanized steel or stainless steel grounding bodies are used, and charcoal and resistance reducing agents are added when the soil resistivity is too high.
爆炸危險場所:設備外殼與接地干線直接連接,禁止串接。
Explosive hazardous areas: The equipment casing should be directly connected to the grounding main line, and serial connection is prohibited.
屋頂設備:金屬外殼僅與避雷帶相連,不得與PE線混接,防止雷電流反灌。
Roof equipment: The metal shell is only connected to the lightning protection strip and must not be mixed with the PE line to prevent lightning current backflow.
五、檢測與維護周期
5、 Testing and maintenance cycle
電阻測試:工作接地每半年一次,保護接地每年一次,使用ZC-8儀表或電流-電壓法。
Resistance test: The working grounding should be conducted every six months, and the protective grounding should be conducted once a year, using ZC-8 instruments or current voltage method.
連接點檢查:每半年緊固螺栓,焊接點防腐處理,移動設備接地線檢查。
Connection point inspection: tighten bolts every six months, perform anti-corrosion treatment on welding points, and focus on inspecting the grounding wires of mobile devices.
腐蝕處理:接地體埋設后每3年開挖檢查,銹蝕截面超30%時更換。
Corrosion treatment: After the grounding body is buried, it should be excavated and inspected every 3 years. If the corroded section exceeds 30%, it should be replaced.
六、常見問題與解決方案
6、 Common Problems and Solutions
接地失效:鋁線連接處氧化導致接觸不良,需改用銅鋁過渡端子。
Grounding failure: Oxidation at the aluminum wire connection leads to poor contact, and copper aluminum transition terminals need to be used instead.
漏接風險:設備維修后易漏接接地線,需在接線圖強制標注接地點。
Risk of missed connection: After equipment maintenance, it is easy to miss the grounding wire, and the grounding point needs to be forcibly marked on the wiring diagram.
跨步電壓:高土壤電阻率區域需增設均壓帶,接地網外緣閉合處理。
Step voltage: In areas with high soil resistivity, a voltage equalization strip should be added and the outer edge of the grounding grid should be closed.
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