Substation Exits

[Kartracer087]

Hey again,

In my quest to further understand utility power networks, I came upon something which I am curious to know. I've seen substations that have three phase feeders leaving the station but no neutral. I know by looking at these particular stations that they use a wye secondary network (ground wire running from neutral terminal of the XFMR to the ground) on the transformer and that they are supplying quite a few single phase loads but I did not see a neutral wire originating from the station. Mainly, the feeders would have three wires or three underground substation exit feeder cables with no neutral (not a concentric neutral type) and they would go to a riser pole such as this one:




Or possibly an above ground feeder like this:




Now, I've seen some stations where the multigrounded neutral is attached straight to the grounding grid and so I am wondering if there is no neutral wire originating from the station, then how can a 3 phase 4 wire system exist? I'm mainly asking this since I'm wondering how you would have single phase feeders (phase to neutral knowing this is how most single phase primaries are connected on end-user transformers) originating from a three phase three wire trunk feeder from the station.

Thanks again! (Sorry for the stupid advertising associated with the pictures, it seems as though everyone these days is out to get your personal information)

 

[gobblerhuntr]

On our system we come out of the station overhead with three phases per circuit and we will tap the ground grid outside the fence and run it underground to the pole. On wood pole structures we don't always pull a neutral per circuit out of the sub but on steel poles we do. If we have four breakers in the sub it is typical for wood poles to bring an underground neutral out on the outside circuits and eventually that neutral will tie to all circuits outta the sub.