Discussion on Grounding Electrode Resistance of Power Supply System in Transformer Substation

LIU Pingzhou（China Aviation Planning and Design Institute（Group）Co.，Ltd.，Beijing 100120，China）

 

 

    Abstract：This article only involves substations the users of which adopt high-voltage measurement and self-management. Power frequency overvoltage in low-voltage systems or conduction breakdown voltage caused by grounding fault voltage in high-voltage system should not exceed over-voltage limit or permissible contact voltage value in low-voltage system. Protection apparatus should be able to shut off power automatically when grounding fault in low-voltage system occurs. Substation grounding electrode resistance is required in national design specification，but the specific value cannot be seen in IEC standard. Accordingly，this article states the different combinations between high-voltage neutral point effective grounding system or non-effective grounding system and low-voltage TN system or T T system，to determine the basic principle of substation grounding electrode resistance for better understanding why grounding electrode resistance is not indistinctly required in IEC standard.

    Key words：functional grounding；protective grounding；grounding electrode resistance；power frequency overvoltage；contact voltage limit；protection against electric shock；effective grounding system；non-effective grounding system

 

    摘 要：本文仅涉及用户为高压计量、自行管理的变电站，高压系统接地故障电压引起低压系统工频过电压或传导故障电压，不应超过低压系统过电压限值或接触电压允许值。低压系统发生接地故障，保护电器应自动切断电源。我国设计规范中给出变电站接地极阻值要求，而在IEC标准未见具体要求值。阐述高压中性点有效接地系统或非有效接地系统，与低压TN系统或T T系统不同组合，确定变电站接地极阻值的基本原则，以更好理解IEC标准未笼统提出接地极阻值要求的原因。

    关键词：功能接地；保护接地；接地极阻值；工频过电压；接触电压限值；电击防护；有效接地系统；非有效接地系统

     中图分类号：TU89        文献标识码：A

     doi：10. 3969 / j. issn. 1003 - 8493. 2016. 03. 003