Sizing Neutral Grounding Reactor or Resistor and Effective Grounding - Part 01

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.

[@eminvalikhanov1245]

Hi sir, in 3 bus 2 generator and 2 transformer system, if I make the value of grounding reactance of generator and the same for a transformer to Zero, what will be expected? Thanks!

[@dustinblotz8894]

At the 8:30 mark you sketch out the SLG fault equivalent circuit. Where do you get the "T-Model" value of 48.49% and the 10.26%?

[@engineeringsimple]

The T-model values would be supplied by the transformer manufacturer either design or tested values.

[@dustinblotz8894]

@@engineeringsimpleThanks for your response. That is what I was assuming, but wanted to make sure since I hadn't heard those terms before.

[@daleschannel309]

At 7:21 you state the high side (+)seq Z=0.2% and the (0)seq Z=0.4%. Where did you get those values.

[@engineeringsimple]

Those values are the system equivalent values. If you have the entire system, you can calculate them. In my case, I just made assumptions based on my experience for the purpose of the calculation. Thanks.