What are the requirements of Distribution equipment grounding resistance (一)
What are the requirements of Distribution equipment grounding resistance (一)
When the building power distribution transformers installed outside the building，must meet the following requirements:
1, for the distribution transformer work on the high pressure side is not grounded , Petersen coil grounded and high- resistance grounded system, when the grounding resistance of the protective earth grounding grid transformers conform formula ( 12.4.3 ) requires no more than 4Ω , the Low system power ground to protect the common ground network and the grounding transformer.
2 , low-voltage cables and overhead lines into the building in place , for the TN-S or TN-CS system , the protective conductor (PE) or protective earthed neutral conductor (PEN) should be repeated grounding resistance and not exceed 10Ω; for TT system protective conductor (PE) alone grounding resistance should not exceed 4Ω;
3 , the high pressure side to the low pressure system working power distribution transformers in when low resistance grounding system , a low pressure system may not be shared with protective earth grounding grid power distribution transformers , low voltage power supply system from the ground should be at an appropriate distribution transformers place setting special grounding grid, the grounding resistance should not exceed 4Ω.
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FATECH ELECTRONIC LTD.
Dec.23,2014
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