network fault monitoring

[SparkyTris]

is it possible for the electricity network operator to monitor the integrity of the Neutral conductors around a network?

if so, how is this done?

 

[ban-all-sheds]

Why do you need to know?

 

[SparkyTris]

why did you feel the need to ask that rather fatuous question?

 

[SparkyTris]

and the answer to your fatuous question is, I do not need to know.
I am merely curious.
this particular splinter of curiosity was piqued by a discussion about the dangers or otherwise of setting up an RF earth in one's garden

 

[bernardgreen]

Normally there is no Neutral in the High Voltage network, ( 11 kV and above )

Neutrals are first "created" at the sub-station or pole transformer.

A three phase HV to 240 volt transformer in the substation has the star point of the 240 v secondary connected to Ground and to the Neutral for the local area.

At a single phase pole transformer the primary is connected between two HV phases and one end of the 240 v secondary is connected to Ground to form the Neutral

 

[bernardgreen]

dangers or otherwise of setting up an RF earth in one's garden

From experience of hill top radio comms sites. Connecting the supply Neutral to a very low impedance Ground mat does not normally present a problem provided the supply Neutral is continuous from substation to ground mat.

 

[SUNRAY]

From experience of hill top radio comms sites. Connecting the supply Neutral to a very low impedance Ground mat does not normally present a problem provided the supply Neutral is continuous from substation to ground mat.

Interestingly a few years back a supply for a hill top aerial site had a problem with floating mains. this was a tap off the HV line some 1/2 mile away with the transformer adjacent to the compound. What had actually happened was the earth wire on the pole was stolen but the DNO's solution was to connect neutral to the station earth.

 

[ban-all-sheds]

why did you feel the need to ask that rather fatuous question?

Because your two questions are just like ones we have seen here many times in the past, where people try to get others to do their coursework for them.

 

[AdrianUK]

Normally there is no Neutral in the High Voltage network, ( 11 kV and above )

Neutrals are first "created" at the sub-station or pole transformer.

A three phase HV to 240 volt transformer in the substation has the star point of the 240 v secondary connected to Ground and to the Neutral for the local area.

At a single phase pole transformer the primary is connected between two HV phases and one end of the 240 v secondary is connected to Ground to form the Neutral

Expanding on what Bernard has said...the primary is, of course, in DELTA thus a neutral is not required on the primary side.... and hence saving the need for a fourth conductor.

A UK distribution transformer is usually configured as a Dyn11.

 

[FrodoOne]

Expanding on what Bernard has said...the primary is, of course, in DELTA thus a neutral is not required on the primary side.... and hence saving the need for a fourth conductor.
A UK distribution transformer is usually configured as a Dyn11.

Since this is a DIY site, it might show consideration to others if those who "know things" could give a supplementary reference (e.g. See xyz) or a little bit of explanation to their (no doubt) quite erudite comments.

I have ascertained that "Dyn11" is a reference to an IEC designation, which indicates a (HV to lv) Delta/star transformer, with an Earthed Neutral on the secondary).
However, I do not see why/how this indicates that "the phase angle of the LV winding lags the HV by 330 degrees, which can also be said that LV windings leads the HV by 30 degrees", as contained in the reference which I located.

It must be in those additional "11" numerals, but why?
If possible, please explain!

 

[Simon35]

Since this is a DIY site, it might show consideration to others if those who "know things" could give a supplementary reference (e.g. See xyz) or a little bit of explanation to their (no doubt) quite erudite comments.

I have ascertained that "Dyn11" is a reference to an IEC designation, which indicates a (HV to lv) Delta/star transformer, with an Earthed Neutral on the secondary).
However, I do not see why/how this indicates that "the phase angle of the LV winding lags the HV by 330 degrees, which can also be said that LV windings leads the HV by 30 degrees", as contained in the reference which I located.

It must be in those additional "11" numerals, but why?
If possible, please explain!

If you imagine a clock face, and the HV winding voltage phasor is at 12 o'clock, then the 11 indicates the LV winding voltage phasor is at 11 o'clock. Assume rotation is anti-clockwise which is IEC convention, then LV is 330 degrees behind HV phasor.

 

[SparkyTris]

From experience of hill top radio comms sites. Connecting the supply Neutral to a very low impedance Ground mat does not normally present a problem provided the supply Neutral is continuous from substation to ground mat.

this is precisely my point - so - please may I ask the question again, is it possible for DNO's to monitor the integrity of a neutral line from substation to consumer(s)? is it ever done? if so, how is it done?
I can see that it *should* not present a problem, but under certain circumstances, it could be dangerous.
stonkingly effective QRO RF earths are likely not going to be intentionally made by anybody that does not also have an understanding of their potential hazard when connected to an elecricity supply network. However, it is also very easy (especially with supplementary bonding) to inadvertently connect a very good RF-thru-DC earth to the network; especially a building with metal subterranean plumbing.

A mitigation of the hazard in the domestic radio shack situation could be to run the shack from an isolating transformer, effectively suplying the shack by a miniature TT arrangement.
what about in the other (domestic, inadvertent) case?

 

[JohnW2]

If you imagine a clock face, and the HV winding voltage phasor is at 12 o'clock, then the 11 indicates the LV winding voltage phasor is at 11 o'clock. Assume rotation is anti-clockwise which is IEC convention, then LV is 330 degrees behind HV phasor.

Are you talking about a transformer fed by one phase of the HV? I thought that the 'final' transformers in the UK were 3-phase HV to single-phase LV (the pole-mounted one which supplies me is certainly fed with all three HV phases, and I'd always assumed that all three were 'connected'). If the later, what is meant by the 'phase' of a 3-phase supply?

Kind Regards, John

 

[JohnW2]

A mitigation of the hazard in the domestic radio shack situation could be to run the shack from an isolating transformer, effectively suplying the shack by a miniature TT arrangement.

I've certainly seen that done, although possibly not primarily for the reason you're discussing.

Kind Regards, John

 

[bernardgreen]

is it possible for DNO's to monitor the integrity of a neutral line from substation to consumer(s)? is it ever done? if so, how is it done?

Measuring the potential between the Neutral and True Ground at the consumer's location will give an indication of a broken or high impedance Neutral conductor to that consumer's location. That said where the load on the network is not balanced evenly across the 3 phases there will be a potential between the Neutral and True Ground due to current flowing through the impedance of the Neutral

Creating a miniature TT arrangement is not un-common where the HV to LV transformer is at risk of metal theft.