Power distribution question

[Golden_Boy]

As the power carried by pylons is 3 phase DELTA, how is there a potential diffrence to earth from any of the phases? Is not the whole lot "floating" with respect to the mass of earth? Or am I missing something???

 

[jeremy]

Absolutely no idea, must have slept through that class!!! Education please Gentlemen!!

 

[pmac10]

this is from wikipedia and sort of half answers your question, i think,

In many areas, "delta" three phase service is common. Delta service has no distributed neutral wire and is therefore less expensive. The three coils in the generator rotor are in series, in a loop, with the connections made at the three joints between the coils. Ground is provided as a low resistance earth ground, sometimes attached to a synthetic ground made by a transformer in a substation. High frequency noise (like that made by arc furnaces) can sometimes cause transients on a synthetic ground.

 

[alarm man]

ex father in law worked on pylons(just a spark as well) absolute mad men the lot of them,has anyone seen the way they replace the cable on those things travelling a long on some sort of bike attached to the cables and they work live as well

 

[Golden_Boy]

this is from wikipedia and sort of half answers your question, i think,

In many areas, "delta" three phase service is common. Delta service has no distributed neutral wire and is therefore less expensive. The three coils in the generator rotor are in series, in a loop, with the connections made at the three joints between the coils. Ground is provided as a low resistance earth ground, sometimes attached to a synthetic ground made by a transformer in a substation. High frequency noise (like that made by arc furnaces) can sometimes cause transients on a synthetic ground.

Synthetic ground ??? Where is this connected??

DELTA = Phase - phase - phase Ground = ?????

 

[Golden_Boy]

this is from wikipedia and sort of half answers your question, i think,

In many areas, "delta" three phase service is common. Delta service has no distributed neutral wire and is therefore less expensive. The three coils in the generator rotor are in series, in a loop, with the connections made at the three joints between the coils. Ground is provided as a low resistance earth ground, sometimes attached to a synthetic ground made by a transformer in a substation. High frequency noise (like that made by arc furnaces) can sometimes cause transients on a synthetic ground.

This would suggest delta / star transformer?

 

[Golden_Boy]

I have done a bit of research and its all to do with capacitance. When I think about it its bleeding obvious.

 

[sparkx]

Hi Guys,

often on delta lines, 'earthing transformers' are used to provide an artificial earth point in the system.

 

[mechelec]

Earth fault protection on three phase delta transmittion lines requires current transformers and senses an imbalance in a three-phase circuit. Normally a three-phase circuit is in balance, so if a single (or multiple) phases are connected to earth an imbalance in current is detected. If this imbalance exceeds a pre-determined value a circuit breaker should operate.