ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Norwegian power?

Im really curios about this, on another forum the main voltages, grounding and bonding were brought up on how they differe across countries. I found out that the IT system with a Delta secondary was the norm in Norway for residential and commercial as apposed to TT and the widly adopted TN-C-S earthing found through out North America and Europe.


Any body know how this system was applied there?

Does anybody have any pictures of residential breaker panels/consumer units in Norway useing IT grounding?

Thanks!

Hi No good pictures just now, but:
pictures (google) http://tinyurl.com/o967hjw

Pretty like 2 phase from your delta 208V except for grounding at transformer.

Fuse or (later 2 pole breaker) on both live live lines to a single phase outlet.

Local grounding similar to NEC. No bonding to N, (no N existing)

It has been used some different arguments to use this system. Most common: A) 3 phase available with 3 wires only. B) safer, because its harmless until fail on the 2'nd phase.

It is pretty common to have 3-phase here, I even have at my cabin. Good for the water pump :-)

Another difference from North American systems: Copper only up to 16 mm^2. Pretty common wit wires on the wall here: (pictures after e lightning accident)



dsk

PS
Ground connections connected at copper clamps under plastic cower in top of cabinet. (pic)
DS

picture

last pic

So essentially the local transformer secondaries are delta-wired without any earth (ground) reference?

Isn't the probability of an earth fault somewhere in the distribution awfully high? Unless I'm seriously mistaken an earth fault in any house or apartment would cause that phase to assume earth potential throughout the wiring on this transformer. In this case, the first fault in any other house would cause a dangerous potential difference.

In order to avoid such unpredictable situations most other countries opted for TN or TT

You are absolutely right.

It will not be used in a new area, but are maintained where it is established. The supply to the house whre the pictures are from are changed to TT when the transformer was changed to supply 20 new buildings, they have 400V TN-C-S, so my guess are just tapping off at 230V for the older buildings.

The IT system made it self to TT at first fault :-)
At second fault, it might start a fire in the first fault location. When no fault the voltage was floating relative to ground, usually stabilized at approx 130V due to capacity to ground.

In Norway even TN-C-S systems have all pole circuit breakers, so even an overload in N will release the circuit.
P (ground) and N are not connected in more than one location in each house.

dsk

Thanks for the insights! No one has been able to provide me with reliable information about Norwegian distribution systems before, so I appreciate your info very much!

BTW, welcome to the message board!


TT using a corner-grounded delta transformer setup... does feel a bit odd!

Thank you, I just saw your question when googeling for something about payphones.
The self grounding TT description are right. It would probably been better with permanent corner grounding.

I will probably not be regular reader, but just pm me if you have questions about Norwegian oddities

I have just made a controller for my American payphone (AE 120B) for use at home, collecting or returning money depending on answer or not.

dsk

Off the subject matter, but.....

It sounds like the 'missing' pay [hones here went to Norway.

The proliferation of cell phones has made the 'pay phone' an item that is really hard to find here. And, when you do find one, the odds are it does not work!

I have the same problem her, but not any more :-)
I have my own. It seemed impossible to get the Norwegian payphone I wanted, so I ended up with the much nicer looking North American one: http://www.classicrotaryphones.com/forum/index.php?topic=11846.15


dsk

PS
You may come her and make your calls, I have pretty good rates on my payphone :-)
DS