Thailand transformer opinions please.

A

ayjay

• Oct 10, 2012

• #16

saw this last year

 

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K

Knobhead

• Oct 10, 2012

• #17

Oi!, I can remember where every wire goes!

 

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K

Knobhead

• Oct 10, 2012

• #18

Neutral to the top, some UK electricity boards used to do that for coastal installs.

 

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A

ayjay

• Oct 10, 2012

• #19

its a bit of a mess tony!
the new buildings have much better wiring supplys but the general ovehead suppys are terrible
there are power cuts when it rains heavily, in the rainy season thats most days
i would have liked to photograph other dangerous stuff but didn,t, as the owners of various premises might not have liked me doing that!
these2 reports are the top of the iceberg, i know of one man that was elecrocuted when he touched the fridge
and a little aussie boy when he plugged in his computer game after he left the pool and was wet
Phuket NEWS: Phuket tourist electrocution sparks probe, safety bli

Briton's electrocution in Phuket was an accident, says court ruling

 

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K

Knobhead

• Oct 10, 2012

• #20

Engineer54 said:

I can't see how the neutral can't be earthed at the TX, otherwise the neutral point will be all over the place unreferenced!!

Click to expand...

The voltage is referenced to it’s self. In testing we always used either – or L2 for our earth free systems, it’s not referenced to earth it just a convenient way for us to record readings. We had both AC and DC systems.
Earth faults are a major headache, you don’t know they are there until you’ve got two of them on opposite lines. Durham mentioned the way ship bourn systems worked a while ago, I think it was similar to what we used.
View attachment 15139

If you want earth leakage detection then it gets complicated, the system we used for the 660V AC system used DC injection through chokes. It was a pain in the backside, it would trip at 20mA on a 2.6MW system.

 

Last edited by a moderator: Oct 10, 2012

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D

Darkwood

• Oct 10, 2012

• #21

I started reading the OP and saw the words 'tranny' and 'Thailand' .... for a minute i thought i was on the wrong forum....:bow:.

 

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K

Knobhead

• Oct 10, 2012

• #22

There isn't a button for throw bucket of cold water!

 

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OP

La Poste

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• Oct 11, 2012

• #23

Great stuff thanks for the replies.

So if I was not sure whether a TX was earthed how would I test this?

Would it be a good idea to bang a nice long rod in and then do a live loop test between supply line and the rod, if I got no reading or infinite resistance would that show the TX was not earthed?

What about taking a voltage measurement between the neutral conductor (assuming it's marked) and true earth?

Is there a method of testing to see whether a TX is earthed or not?

 

Last edited: Oct 11, 2012

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K

Knobhead

• Oct 11, 2012

• #24

That would be quick and easy.

 

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OP

La Poste

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• Oct 11, 2012

• #25

Tony said:

That would be quick and easy.

Click to expand...

Sorry Tony I don't understand what you mean by quick and easy.
Are you saying my method is quick and easy?

 

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K

Knobhead

• Oct 11, 2012

• #26

Yes, may take you a while to get there though.

 

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E

Engineer54

• Oct 11, 2012

• #27

Tony said:

The voltage is referenced to it’s self. In testing we always used either – or L2 for our earth free systems, it’s not referenced to earth it just a convenient way for us to record readings. We had both AC and DC systems.
Earth faults are a major headache, you don’t know they are there until you’ve got two of them on opposite lines. Durham mentioned the way ship bourn systems worked a while ago, I think it was similar to what we used.
View attachment 15139

If you want earth leakage detection then it gets complicated, the system we used for the 660V AC system used DC injection through chokes. It was a pain in the backside, it would trip at 20mA on a 2.6MW system.

Click to expand...

Not sure how that would work on a distribution system covering several consumers, with different loads on different phases... And as you say RCD's (which they use in abundance) wouldn't functioning to well.

 

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K

Knobhead

• Oct 11, 2012

• #28

Engineer54 said:

Not sure how that would work on a distribution system covering several consumers, with different loads on different phases... And as you say RCD's (which they use in abundance) wouldn't functioning to well.

Click to expand...

The very thought of it gives me a headache.

Will PM a drawing of what we used for 660V

 

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OP

La Poste

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• Oct 12, 2012

• #29

Here's a few more cropped images of the TX, it does look like at least one cable has been anchored to the pole by means of a bolt.

Maybe this is evidence of the steel within the pole being used as an earth.

I like the tap at the bottom of the TX, I've never seen one of those before.

 

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K

Knobhead

• Oct 12, 2012

• #30

Looks like that's the mystery solved. I'll admit, I'd never have thought of using the poles reenforcing as an Ufer earth.

PS the tap, all oil filled transformers have them. Usualy with a bung fitted. They are especialy designed for numb-nuts elecricians mates to leave part open, as i found out in the middle of the night when half the works shut down. 20MVA transformers don't like running low on oil.

 

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