Professional interpretation, grounding resistance values and details of pad mounted transformer

Pad mounted transformer is an outdoor power supply equipment that includes high-voltage incoming and outgoing lines, metering devices, transformers, low-voltage incoming lines, and low-voltage distribution outgoing lines. The advantages of pad mounted transformer are: small footprint, reduced civil foundation costs, small size, light weight, and convenient installation and movement. Widely used in general urban load intensive areas, rural areas, residential communities, park power distribution and other installations, it is conducive to high-voltage extension, reducing the power supply radius of low-voltage lines, and reducing line losses.

 

I believe many people are not very clear about the grounding resistance standards for pad mounted transformer. Qingdao Hengfengyou Electrical Engineer will give a brief explanation based on years of work experience.

 

 

Grounding is an electrical safety measure taken to ensure the normal use of electrical equipment and personnel safety. Grounding is achieved by connecting metal wires to the grounding device. The potential leakage current generated by the grounding device

Static charges and lightning currents are introduced underground, avoiding personnel electric shock and potential fire and explosion accidents. Using structure as the main body, connecting body, and reinforced structure. The actual effect of grounding is mainly judged by the resistance value of the grounding resistance. Increasing the power saving resistance is not good for grounding. The grounding method for high-voltage systems is non grounding. When high resistance grounding is used, the grounding fault current on the high-voltage side is relatively small, generally not greater than 10A. Fault generated on the Rb of the grounding resistance of the box transformer.

 

The voltage drop is 4 * 10=40V. The system grounding of low-voltage power distribution and the protective grounding of high-voltage power distribution equipment are often common Earth electrode, so the grounding potential of pe line at the low-voltage side also rises to 40v. This value is less than the 50V limit for personnel being electrocuted, so when a grounding fault occurs on the high-voltage side

 

The probability of causing a low voltage side click to try will be very low.