SINGLE WIRE EARTH RETURN (SWER) - not the same as "Multi Grounded Neutrals"

[Birken Vogt]

Where I grew up in Penn Valley I assume was built in the late 60s/early 70s and all 21 kv, I always assumed it was the long distances to the sub. The only other one I am aware of is in the Plumas Lake area south of Marysville, probably like you say because it is a new build. Everywhere else is a bunch of 12 kv but the areas I go have not seen any wholehearted new construction in ages, mostly just extensions onto existing.

I suppose in the San Jose area there may be a lot more new going on.

 

[mtnelect]

This is verified by the Institute of Electrical and Electronic
Engineers’ Standard 141, titled, “IEEE Recommended
Practice for Electrical Power Distribution for Industrial Plants”
and IEEE Standard 241, titled, “Recommended Practice for
Electric Power Systems in Commercial Buildings” [17].
Why should one industry, the utility industry, be allowed to
use transformers with such a non-standard transformer
connection considered unsafe and/or unknown of by the vast
majority of electrical engineers just because it saves money?

This attachment is an excerpt from the original article. https://electrical-engineering-portal.com/

 

[winnie]

@mtnelect you create confusion and dilute your point when you equate MEN systems (which are very common) to SWER systems.

In the common MEN system there is a neutral wire, and it goes all the way back to the substation. Saying that there isn't such a wire is simply incorrect and distracts from the point you are trying to make.

This neutral wire is _shared_ with the low voltage neutral, and is grounded at multiple locations, making the Earth a parallel path for the neutral.

To the extent that the utilities are willing to tolerate high neutral currents and thus elevated neutral voltages, this injects current into the soil.

You are not going to be able to get rid of grounded primary distribution. Even if you convince people that routine injection of current into the Earth is a sufficient problem that it be mitigated, you are not going to get rid of the need for effective grounding without using an entirely different method of power distribution.

Instead of equating what us actually done with SWER, describe what the utilities should be doing better with the system they actually have.

Jon

 

[electrofelon]

.

The utility saves the cost of a dedicated wire for the neutral, which would have to go all the way back to the substation. So, they just drive a ground rod at each pole and it "Leap Frogs" back to the substation ground rod to ground rod. All the while dumping gradient into the earth all the way back.

Funny how you are so vehemently against this but yet you seem to have no clue how the connections are actually made. What you say is completely false and not a thing.

 

[Birken Vogt]

Another thing, the utilities go to pains to measure their current per leg under various conditions and times of year, and make sure it stays relatively balanced. I always figured it was because they want their 3 phase generation to be balanced and their transformers to be balanced, but it also has the effect of making the actual neutral current nearly net zero.

 

[LarryFine]

Another thing, the utilities go to pains to measure their current per leg under various conditions and times of year, and make sure it stays relatively balanced. I always figured it was because they want their 3 phase generation to be balanced and their transformers to be balanced, but it also has the effect of making the actual neutral current nearly net zero.

Just like we're supposed to strive for.

 

[AlbertL57]

To me, the strength of MGN is its redundancy, but its weakness is that the redundancy lacks monitoring, so it's unknown if a given system is down to the maximum safe ground resistance due to a number of grounds failing. We've all read the stories of the plumber who was shocked when disconnecting a water-pipe ground to make repairs.

 

[CableGuy10]

Nice discussion you guys have here.

SWER uses the mass of the earth and as the neutral conductor. The cost of running wires to peoples houses is significant and is usually grossly disproportional. In terms of earthing hazards, it is somewhat less of an issue than urban areas (less exposure) and the fault current is not high (250A)

MEN/CMEN/MGN is a very useful method for dealing with earthing hazards for distribution and transmission companies. It effectively makes the system overall safer, particuarlly those people that reside near substations. The issues you guys need to understand is the concepts of earthing, and how much voltage is generated with an earth fault. Voltages generated by earth faults are a function of impedance and current, V=IZ where Z = the effective earth/ground impedance of a pole, house earthing etc. An MEN system results in everything, poles, houses carrying a percentage of the fault back to the source, and will also depend on the distance from said source (series and parallel resistances for the return path).

If there are not enough poles and houses on an MEN, the companies will typically separate the HV/LV earthing systems.