Sizing Neutral Grounding Reactor or Resistor and Effective Grounding - Part 02

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.

[@mr123john4]

Why do we want to limit the ground fault to 6000amps? where is that number came from?

[@engineeringsimple]

I just picked 6000A to show how to limit the fault current. In real applications, the breaker capability will determine what to limit the current to. If you have multiple breakers at a substation, it may cost more to purchase them with the available fault current. Instead I t may be cost effective to use a neutral grounding reactor or resistor to limit current to a certain level.

[@yanpetit]

Hello, in your Z0eq equation, where does the 1.02 come from?

[@yanpetit]

I just noticed this question is answered in Sizing Neutral Grounding Reactor or Resistor and Effective Grounding - Part 05. cheers.