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You are right there Trumpy, it didn't even cross my mind, of course ! there is no areal or controlbox. I must have been in holiday mode

The ddo supports have seen better days although the transformer looks reasonably new. Other sides I have seen used to have 2 transformers back to back, instead of this single tank TX.

Bump !

As discussed in the other thread, this is a SWER isolating transformer on the photo.

Primary is at 2Ø 11 kV . (look at the 2 ddo's).
Secondary is 1Ø 11 kV SWER. (1 ddo)
and transformer secondary winding is internally connected to the small white insulator. One of the outgoing earth wires will go to the tank, the other to the earthbank. Load is usually limited to 8 Amps @ 11 kV.

It's not too clear on the photo but the earth wire is visible on the RHS of the 2 tapchangers from the small white insulator.
That earth wire goes to a very good earth bank with earth rods and bare strip earth wires to avoid any step voltages nearby the transformer.

The transformers down the SWER line are standard 11 kV 1Ø transformers, which can be used from a 2Ø 11 kV supply or from a 1Ø 11 kV SWER "washing line".

To answer some of Rodalco's original questions:

I think the most common voltage for new installs is 19 kV. I know it is in some African countries (like Namibia) and I've seen transformers for this voltage from Thai manufacturer as well. You can use the same insulators as for 33 kV 3-ph systems.

Distribution systems up to 33 kV have been built, in South Africa e.g.

If you run the calculations, you will see that raising the voltage overcomes some of the inherent limitations of a SWER system. You get other problems instead, of course.

Suggestions for 80 kV, 6 MW SWER transmission systems have been made for Alaska. Not built, AFAIK.

Well, the poles are about 40 years old, if that's a date on one.

Alan

Correct. In NZ most poles will have the
date of manufacture on them.
They used to be made within the local POCO's
concrete plant.

The actual transformer is less than 10 years old. Powerboard used to put 2 tranny's back to back to make up the SWER system. 11kV - 11kV (isolation tranny) 11kV - Earth. SWER.

More pics of the SWER system can be found here in the Photos Area.