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Distribution Transformers

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Well-Known Member
As said in the other thread, distribution transformer explosions, i think it is a good idea to keep this topic distribution transformers under a different thread where we also can discuss different power systems as well for people who are interested.

As i promised i would attach some overhead TX's and here they are.
These photo's were taken today.
One taken in Whangaparoa, 50 kVA, (middle 2)
Also a shot of the ddo's ( dominion drop out fuses )
other in New Lynn, Tomo st. 200 kVA with vent pipe ( left )
last one in Titirangi, Mc Eldownie rd, 100 kVA. ( right )

Normal system used in New Zealand is 11 or 22 kV for distribution and 230 / 400 Volts for supply at 50 Herz.



New Member
that last one looks really old! thanks for the pics!


Well-Known Member
Here are two photo's from a new ground mounted transformer on a pad and adjacent to it is a 11 kV ring mains unit ( andelect )
Photo's taken at Whangaparoa road.
This is a 100 kVA TX, supplying power to a couple of houses and streetlighting in the area.
The relays in the grey box are for hotwater and streetlight control.

Any one around the world with interesting transformer set ups, could make a great addition to this interesting topic.
As electronics enthousiasts we rely on electricity, and it is important to know what supplies our workshops.

Looking forward to a discussion or photo's


Grant Fleming

New Member
Very good pics! I find H.V distribution/transformers always an interesting topic. The vent pipe is a little scary-wouldn't want to be standing underneath it if things hotted up!



Well-Known Member
Transformer cores

Attached are some digital photo's i took from old 35 mm photo's i took when i worked at the WEPB in Henderson, West Auckland, New Zealand.

We converted pole type transformers into ground mounted distribution TX's which involved rewiring the off load tapchanger and LV cables to the bushings.

100 kVA WEPB with copper windings.

500 kVA ECC with copper windings.

200 kVA Tyree with aluminium primary and Al flat strip winding as secundairy.



Well-Known Member

This photo is from a "cooked" TX.
It is from another Tyree 200 kVA TX which has been heavily overloaded in an industrial area.
The TX survived but customers were complaining about low voltage.

TX details:
200 kVA
11 kV - 230/400 Volts
I continuous at primairy 11 Ampères per phase.
I continuous at secundairy 278 Ampères per phase.

This TX was replaced with a 500 kVA TX and the daily 8 hour load was 650 Ampères per phase.
That one takes 596 Ampères per phase.
That is well over twice the continuous current the TX is designed for.

The oil is black tar cooked oil.
Normally the oil turns yellowish/brown after years of service but not black.

New insulating and cooling oil is clear with a bluish tinge.


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