Mutiple Power Source Neutral Bonding.

[charlie b]

This is not a problem. Current will always find its way back to its source. If the generator is on line, it is the source. Current leaving the generator and heading to the 3 phase loads will return either by the phase conductors (if all is balanced) or by the neutral (if there is some imbalance). Once it returns to the N-G bond point on the generator system, the fact that the utility?s neutral is essentially connected to that same point is not relevant. Current will not flow backwards along the utility?s neutral and into the utility?s distribution system, because there is no driving force to push it in that direction. The same is true for current leaving the generator and heading towards the single phase loads.

 

[Krim]

This is not a problem. Current will always find its way back to its source. If the generator is on line, it is the source. Current leaving the generator and heading to the 3 phase loads will return either by the phase conductors (if all is balanced) or by the neutral (if there is some imbalance). Once it returns to the N-G bond point on the generator system, the fact that the utility?s neutral is essentially connected to that same point is not relevant. Current will not flow backwards along the utility?s neutral and into the utility?s distribution system, because there is no driving force to push it in that direction. The same is true for current leaving the generator and heading towards the single phase loads.

Thank you Charlie B for explaining this issue. With the highlighted (in red) statement above of your quote in mind, are you stating that the current created by the generator would not be considered enough of a driving force in the event of a short circuit to cause any harm at all with the neutrals interconnected ?
I was certain that this would or at least could cause serious damage either to the utilities equipment or the generator itself .
I'm not going to dispute what you've stated, considering you are an electrical engineer and obviously are far more educated than I, but this certainly does baffle me .
Thanks again.
Carl

 

[Krim]

Switched neutral with a seperately derived system is a better option in this case, but I quess the PoCo don't find many transfer switches doing this, the way they want, so they direct connecting neutrals together.

Thanks LISHAJI for the update, I still don't quite understand the PoCo approving this, but I'm not an electrical engineer and are certain there's alot about electricity that I don't yet understand.
Take care.
Carl

 

[charlie b]

. .. are you stating that the current created by the generator would not be considered enough of a driving force in the event of a short circuit to cause any harm at all with the neutrals interconnected ?

No. It is not a matter of "enough driving force." I am saying that that is not the direction of the push. The push is in the direction that would take the current back to its source. Once it reaches there, once it hits the N-G bond point, it will go through the source and start its journey towards the loads again. There no nothing to push the current from the N-G bond point of the source in the direction of the other sources whose neutral points are connected to each other.

 

[Krim]

No. It is not a matter of "enough driving force." I am saying that that is not the direction of the push. The push is in the direction that would take the current back to its source. Once it reaches there, once it hits the N-G bond point, it will go through the source and start its journey towards the loads again. There no nothing to push the current from the N-G bond point of the source in the direction of the other sources whose neutral points are connected to each other.

Charlie B ,
I believe I understand the basic physics involved now.
Thanks again for your professionalism as well as for your patience and time to clarify this matter for me.
Sincerely,
Carl