SWER vs HVDS systems in Power Distribution

[itsEEE]

Hey everyone,
I just wanted to know that what are the differences between the power system principles between a High Voltage Distribution System (HVDS) where a single-phase transformer 11Kv/440V is used, and a Single Wire Earth Return system (SWER). Are these the same and only differ in the application or something else is there?

Following is the image of SWER

 

[waross]

In practice you may find that the isolating transformer is actually a step down transformer stepping down from a higher transmission voltage.
That is a common arrangement where I used to live.
That is; A transformer stepping down from transmission voltage to feed an SWER for distribution.
I suggest that an isolating transformer may be used to solve occasional local issues.
One possibility is that the isolating transformer, be it 1:1 or some other ratio will limit the Available Short Circuit Current on the SWER system.
This may be a safety issue.
The higher the ASCC on an SWER system, the higher voltage and the greater area of touch and step potentials in the event of a ground fault.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[itsEEE]

Thank you @waross for your valuable input, but still I am a little bit confused with SWER and HVDS systems. Are they same or they have any differences?

 

[waross]

In the area that I am familiar with, transmission is generally at over 100kV.
The substation or "isolating" transformers step down to 35kV or less (11kV in your example) for distribution and reduce the ASCC.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[itsEEE]

Thank you
Others are open to share their views.

SNTdon