What are these transformer looking like things?

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In summary: It is definitely some sort of disconnect switch.Why would they have something like this on a power line?In summary, this object is a recloser, which is used to open and close a power line in the event of a fault. It is typically used on rural distribution lines, where the most common causes of faults are rodents or birds shorting the line to ground or falling tree branches.
  • #1
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I have seen these transformer like things on the higher voltage powerlines when I go to regional areas in NSW (Australia) and I was wondering what they are?
They couldn't be transformers because they are not connected to any other wires.
Would love any insights.
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  • #2
That is strange looking. Note the pole that runs partway down toward the ground.

My guess is that it is an enclosed disconnect switch. With the power off, a lineman can reach up to that pole and open/close the switch.

Why disconnect? Mostly for maintenance purposes.

Here are pictures of open-air versions of disconnects.

1671622673494.png
1671622694156.png
 
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  • #3
anorlunda said:
That is strange looking. Note the pole that runs partway down toward the ground.

My guess is that it is an enclosed disconnect switch. With the power off, a lineman can reach up to that pole and open/close the switch.

Why disconnect? Mostly for maintenance purposes.

Here are pictures of open-air versions of disconnects.

View attachment 319142View attachment 319143
Cool! Thanks so much for that

is the pole running down the pole to ground it is they want to turn it off?
 
  • #4
I think that pole is just an extended handle. It can be reached with a hand-held pole from the ground. If it went all the way to the ground, they would need a fence to prevent ordinary people from fooling with it.
 
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  • #5
Agreed - looks like a sectionalizer, possibly with vacuum interrupters allowing it to offer protection, as well as remote connection / disconnect control - as well as manual isolation.
 
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  • #6
That may be a recloser.
If you live in a rural area, you have probably noticed the power blinking off for a few seconds.
The most common causes of faults on rural distribution lines are momentary faults caused by rodents or birds shorting the line to ground or by falling tree branches. The second most common cause of faults is either a bad short on a secondary circuit or a burned out transformer.

The recloser instantly opens the circuit in the event of any over-current and then recloses a few cycles or seconds later. If the fault is still present the recloser will open again after a few cycles. This may be repeated three times, giving the rodent or tree branch a chance to fall away from the line and clear the fault.

If the fault does not clear after three tries, it may be a shorted distribution transformer. The recloser will then close in for a longer time to try to clear the local fuse at he transformer.
After a total of five tries, the recloser will remain open until manually reset.
It has been a long time and I forget the typical recloser time settings. In any event the operation is controlled by a micro computer and the system engineer is free to program it any way he chooses.

BUT
Reclosers are typically single phase and that looks like a three phase unit.
There are some power systems that have a tendency to back feed into a fault from either a delta secondary or from a transformer that magnetically develops a phantom delta.
These systems would use three phase reclosers.

anorlunda may be correct and that may be an interrupter of some sort.
The odds are probably 90/10 in favour of Anorlunda's suggestion.
 
  • #7
waross said:
That may be a recloser.
If you live in a rural area, you have probably noticed the power blinking off for a few seconds.
The most common causes of faults on rural distribution lines are momentary faults caused by rodents or birds shorting the line to ground or by falling tree branches. The second most common cause of faults is either a bad short on a secondary circuit or a burned out transformer.

The recloser instantly opens the circuit in the event of any over-current and then recloses a few cycles or seconds later. If the fault is still present the recloser will open again after a few cycles. This may be repeated three times, giving the rodent or tree branch a chance to fall away from the line and clear the fault.

If the fault does not clear after three tries, it may be a shorted distribution transformer. The recloser will then close in for a longer time to try to clear the local fuse at he transformer.
After a total of five tries, the recloser will remain open until manually reset.
It has been a long time and I forget the typical recloser time settings. In any event the operation is controlled by a micro computer and the system engineer is free to program it any way he chooses.

BUT
Reclosers are typically single phase and that looks like a three phase unit.
There are some power systems that have a tendency to back feed into a fault from either a delta secondary or from a transformer that magnetically develops a phantom delta.
These systems would use three phase reclosers.

anorlunda may be correct and that may be an interrupter of some sort.
The odds are probably 90/10 in favour of Anorlunda's suggestion.
Thanks so much for your answer waross.

It seems and amazing coincidence that I saw this while walking my dog just last week and wondered what it was.

IMG_4067.jpeg

After a bit of Googling around I found out it was a recloser. I spent a bit of time learning about what they actually did too. You explanation is kinda how I understand how they work now, so that validates my efforts.. lol

On another forum they were pretty confused about that post too, but one of them emailed a person they knew in Australia, and she sent me this link.

https://insulect.com/products/gas-insulated-load-break-switches

so... there you go.. it is a disconnecting thingy (whatever they're called).

I think it must be just an Australian type.

I really appreciate your response.
 
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