Sizing Neutral Grounding Reactor or Resistor and Effective Grounding - Part 04

This video series provide details on line to ground fault calculations, using symmetrical components. The calculations are done with an example of a 138/12 kV grounded wye-grounded wye transformer. In this example, the low voltage line to ground fault current is 11,000 Amps. Two options are explored to limit the fault current to 6000 Amps. Option 1 is to add a neutral grounding reactor. Option 2 is to add a neutral grounding resistor. In each option, the required reactance or resistance is calculated. Then effective grounding of the system was verified for each option.

[@engineeringsimple]

Thanks for watching! Let me know if you have any questions or would like a certain topic covered in the future.

[@jasonhuffine5292]

Hi, great video! When calculating reactance, to get 0.5464ohms, the 9.49% has to be divided by 100% to get pu so that the Zbase can be used. With the resistance, this wasn't done, leaving 100.6ohms instead of 1.006ohms. Is that correct?

[@engineeringsimple]

Thank you. You are correct. The percent value should have been divided by 100 when calculating ohms. Instead of 100.6 ohms, it should be 1.006 ohms. Thank you for the catch.