tailieunhanh - LV Distribution

Tham khảo tài liệu 'lv distribution', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter E LV Distribution Contents 1 Earthing schemes Earthing connections E2 E2 Definition of standardised earthing schemes E3 Characteristics of TT TN and IT systems E6 Selection criteria for the TT TN and IT systems E8 Choice of earthing method - implementation E10 Installation and measurements of earth electrodes E11 2 The installation system Distribution switchboards E15 E15 1 Cables and busways E18 3 External influences IEC 60364-5-51 Definition and reference standards E25 E25 Classification E25 List of external influences E25 Protection provided for enclosed equipment codes IP and IK E28 E1 Schneider Electric - all rights reserved Schneider Electric - Electrical installation guide 2010 1 04 12 2009 E - Distribution in low-voltage installations 1 Earthing schemes E2 Schneider Electric - all rights reserved In a building the connection of all metal parts of the building and all exposed conductive parts of electrical equipment to an earth electrode prevents the appearance of dangerously high voltages between any two simultaneously accessible metal parts 3 3 Branched protective conductors to individual consumers Extraneous conductive parts Heating 5 4 3 Main protective conductor Water Gas 5 5 6 Fig. El An example of a block of flats in which the main earthing terminal 6 provides the main equipotential connection the removable link 7 allows an earth-electrode-resistance check Earthing connections Definitions National and international standards IEC 60364 clearly define the various elements of earthing connections. The following terms are commonly used in industry and in the literature. Bracketed numbers refer to Figure E1 Earth electrode 1 A conductor or group of conductors in intimate contact with and providing an electrical connection with Earth cf details in section of Chapter E. Earth The conductive mass of the Earth whose electric potential at any point is conventionally taken as .