Disadvantage of having high neutral grounding resistance

In summary, the conversation discusses the potential addition of high resistance neutral grounding to limit line to ground faults in an industry that involves manual bus bar shorting and the use of neutral for welding and grinding purposes. The speaker is unsure of the disadvantages and design freedom in implementing this and is advised to consult with a professional trained in this area and familiar with applicable codes for safety reasons.
  • #1
nand arora
16
0
I am working in an industry where my technicians have to short the bus bars on regular basis (manually) for some maintenance purposes.

I want to add high neutral grounding resistance to the incoming supply transformer to limit the Line to ground fault. Presently the neutral has been solidly grounded. What will be the disadvantages of high resistance neutral grounding?

We are using neutral for some (single phase) welding and grinding purpose.
 
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  • #2
I have never seen any transformer with very high neutral grounding resistance. It is uaually around 9.5 ohms. Can I have 1k ohm resistance. What will be its disadvantages?

And yes, I do have an Earth fault relay in neutral. But still I don't want the fault current (which may pass through the technician's body in worst case scenario) to be more than 5 milli amps.
 
  • #3
I don't know the specific answer to your question. But I think that this is an area where codes can be strict and you may not have much design freedom. My recommendation is to check the applicable codes first to see what is permitted.
 
  • #4
I think you should further specify the type of that 'industry'. I were just about to reply something what I think would have been totally irrelevant judged by your posts on other topics.

What range of kilovolts and kiloampers?
 
  • #5
Please consult with a professional who is trained in this area and knows the applicable codes and such. We do not want your technicians getting injured or killed because someone accidentally gave you incorrect information.

Thread locked for safety reasons.
 
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Likes dlgoff and jim hardy

1. What is the purpose of neutral grounding resistance?

Neutral grounding resistance is used to limit the fault current in a power system. It helps to protect equipment and prevent damage in the event of a ground fault.

2. What is considered a high neutral grounding resistance?

The specific value of a high neutral grounding resistance can vary depending on the power system and equipment. Generally, a resistance greater than 5 ohms is considered high.

3. What are some disadvantages of having a high neutral grounding resistance?

One major disadvantage is that it can increase the duration of a fault, which can lead to more damage and longer downtime for equipment. It also reduces the effectiveness of ground fault protection systems.

4. How does a high neutral grounding resistance affect system stability?

A high neutral grounding resistance can cause voltage instability and unbalance in a power system. It can also lead to transient overvoltages and decrease the ability to control the system.

5. How can a high neutral grounding resistance be mitigated?

One option is to install a low resistance grounding system, which can reduce the duration of a fault and improve system stability. Another method is to use a ground fault detection system to quickly isolate faults and minimize their impact.

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