Earthing Cable having Current

[ajaygautam]

[FONT=&quot][FONT=Calibri,sans-serif]Hi Good Morning Mike,
[/FONT]How r u?
Hope all is well

Pls help me to resolve the Electrical Problem. I am getting huge ampere in Earthing Cable. Earthing Cable is coming from Earth Pit. Then this Earthing Cable is fitted on Earth Bar. On this earth Bar, I am getting 135 Amp on Main Earthing Cable. When i am going to check Randomly on any panel like Sub Distribution Panel[/FONT]
[FONT=&quot][FONT=Calibri,sans-serif]Main Incomer Breaker 1000 Amp MCCB
[/FONT]R Phase- 81 Amp
Y Phase- 92 Amp
B Phase- 80 Amp
Neutral - 18 Amp
Earth - 18 Amp
I am thinking that may be Phase Cable Insulation failure or Neutral Cable inter change with Earthing Cable. [/FONT]
[FONT=&quot][FONT=Calibri,sans-serif]Outgoing Branch 100 Amp MCCB
[/FONT]R Phase- 3.4 Amp
Y Phase- 0.5 Amp
B Phase- 0.3 Amp
Neutral - 2.8 Amp

​​I am thinking that may be due to Unbalance Load [/FONT]
[FONT=&quot][FONT=Calibri,sans-serif]What do you think, where is the problem and what can be a cause?

Please Advise[/FONT][/FONT]
[FONT=&quot][FONT=Calibri,sans-serif] [/FONT][/FONT]
[FONT=&quot][FONT=Calibri,sans-serif] [/FONT]
[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]Ajay Kumar Gautam[/FONT][FONT=Calibri,sans-serif]
Electrical Engineer[/FONT][/FONT]

[/FONT]

 

[Buck Parrish]

What is the voltage on your grounding electrode ? (Earthing ground)

 

[topgone]

[FONT=&quot][FONT=Calibri,sans-serif]Hi Good Morning Mike,
[/FONT]How r u?
Hope all is well

Pls help me to resolve the Electrical Problem. I am getting huge ampere in Earthing Cable. Earthing Cable is coming from Earth Pit. Then this Earthing Cable is fitted on Earth Bar. On this earth Bar, I am getting 135 Amp on Main Earthing Cable. When i am going to check Randomly on any panel like Sub Distribution Panel[/FONT]
[FONT=&quot][FONT=Calibri,sans-serif]Main Incomer Breaker 1000 Amp MCCB
[/FONT]R Phase- 81 Amp
Y Phase- 92 Amp
B Phase- 80 Amp
Neutral - 18 Amp
Earth - 18 Amp
I am thinking that may be Phase Cable Insulation failure or Neutral Cable inter change with Earthing Cable. [/FONT]
[FONT=&quot][FONT=Calibri,sans-serif]Outgoing Branch 100 Amp MCCB
[/FONT]R Phase- 3.4 Amp
Y Phase- 0.5 Amp
B Phase- 0.3 Amp
Neutral - 2.8 Amp

​​I am thinking that may be due to Unbalance Load [/FONT]
[FONT=&quot][FONT=Calibri,sans-serif]What do you think, where is the problem and what can be a cause?

Please Advise[/FONT][/FONT]
[FONT=&quot][FONT=Calibri,sans-serif] [/FONT][/FONT]
[FONT=&quot][FONT=Calibri,sans-serif] [/FONT]
[FONT=Times New Roman,serif][FONT=Calibri,sans-serif]Ajay Kumar Gautam[/FONT][FONT=Calibri,sans-serif]
Electrical Engineer[/FONT][/FONT]

[/FONT]

If your loads are line to neutral with line current 81, 92 and 80 A repectively, the neutral current should have been just around 12A! I guess you have some errors in your readings, that's all. The neutral current is a result of unbalanced loading.

 

[Julius Right]

The neutral current could be normal if the power factor is different in each phases.
If all pf in each phase is the same then neutral current will be 11.5 A.
For instance if pf in R is 0.8 in Y 0.8 but in B it is only 0.74 then the neutral current is 18.4 A
The grounding current is not connected with phase current. It could be a part of utility grid grounding current if the local grounding resistance is low with respect utility grounding resistance. It could be also a capacitive current from the supply grid.
In any case the phase-to-ground voltages has to be checked.

 

[Smart $]

Are there any other systems tied into the same transformer. For example, around here the power company may use one transformer [bank] to power several services. Sometimes there is an open or resistive neutral on another system and the fault current goes through its earthing system to yours and back to the power company transformer.

As mentioned, with the numbers provided for your 1000A CB, you could easily see 12A on your neutral... but not both neutral and the earthing conductor... not to mention you have 18A on both.

Can you clamp both neutral and earthing conductor at the same time? If you can, measure one way then reverse the direction of one wire and measure again. One way sums, the other provides the difference. Use KCL as you have a three branch analysis line, load, and earth.

 

[kwired]

Are there any other systems tied into the same transformer. For example, around here the power company may use one transformer [bank] to power several services. Sometimes there is an open or resistive neutral on another system and the fault current goes through its earthing system to yours and back to the power company transformer.

As mentioned, with the numbers provided for your 1000A CB, you could easily see 12A on your neutral... but not both neutral and the earthing conductor... not to mention you have 18A on both.

Can you clamp both neutral and earthing conductor at the same time? If you can, measure one way then reverse the direction of one wire and measure again. One way sums, the other provides the difference. Use KCL as you have a three branch analysis line, load, and earth.

The POCO's here also use common conductor as a grounded conductor on both primary and secondary, meaning even someone supplied by a separate transformer could have stray current flowing in your place via that common grounded conductor, especially if some connection in the intended current path should become higher in resistance.

 

[Smart $]

The POCO's here also use common conductor as a grounded conductor on both primary and secondary, meaning even someone supplied by a separate transformer could have stray current flowing in your place via that common grounded conductor, especially if some connection in the intended current path should become higher in resistance.

Good point.