1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

network fault monitoring

Discussion in 'Electrics UK' started by SparkyTris, 18 Nov 2018.

  1. SparkyTris

    SparkyTris

    Joined:
    24 Nov 2004
    Messages:
    390
    Thanks Received:
    4
    Country:
    United Kingdom
    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?
     
  2. Sponsored Links
  3. ban-all-sheds

    ban-all-sheds

    Joined:
    27 Aug 2003
    Messages:
    69,784
    Thanks Received:
    2,857
    Location:
    London
    Country:
    United Kingdom
    Why do you need to know?
     
    • Thanks Thanks x 1
  4. SparkyTris

    SparkyTris

    Joined:
    24 Nov 2004
    Messages:
    390
    Thanks Received:
    4
    Country:
    United Kingdom
    why did you feel the need to ask that rather fatuous question?
     
  5. SparkyTris

    SparkyTris

    Joined:
    24 Nov 2004
    Messages:
    390
    Thanks Received:
    4
    Country:
    United Kingdom
    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
     
  6. bernardgreen

    bernardgreen

    Joined:
    3 Nov 2006
    Messages:
    24,127
    Thanks Received:
    2,346
    Location:
    Bedfordshire
    Country:
    United Kingdom
    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
     
  7. bernardgreen

    bernardgreen

    Joined:
    3 Nov 2006
    Messages:
    24,127
    Thanks Received:
    2,346
    Location:
    Bedfordshire
    Country:
    United Kingdom
    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.
     
  8. SUNRAY

    SUNRAY

    Joined:
    28 Jul 2009
    Messages:
    3,835
    Thanks Received:
    259
    Location:
    Kent
    Country:
    United Kingdom
    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.
     
  9. ban-all-sheds

    ban-all-sheds

    Joined:
    27 Aug 2003
    Messages:
    69,784
    Thanks Received:
    2,857
    Location:
    London
    Country:
    United Kingdom
    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.
     
  10. Sponsored Links
  11. AdrianUK

    AdrianUK

    Joined:
    22 Sep 2009
    Messages:
    537
    Thanks Received:
    80
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    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.
     
  12. FrodoOne

    FrodoOne

    Joined:
    20 Feb 2017
    Messages:
    408
    Thanks Received:
    46
    Location:
    Melbourne, Australia
    Country:
    Australia
    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!
     
  13. Simon35

    Simon35

    Joined:
    27 Sep 2011
    Messages:
    528
    Thanks Received:
    58
    Location:
    Yorkshire
    Country:
    United Kingdom
    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.
     
  14. SparkyTris

    SparkyTris

    Joined:
    24 Nov 2004
    Messages:
    390
    Thanks Received:
    4
    Country:
    United Kingdom
    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?
     
  15. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    45,046
    Thanks Received:
    2,875
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    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
     
  16. JohnW2

    JohnW2

    Joined:
    28 Jan 2011
    Messages:
    45,046
    Thanks Received:
    2,875
    Location:
    Buckinghamshire
    Country:
    United Kingdom
    I've certainly seen that done, although possibly not primarily for the reason you're discussing.

    Kind Regards, John
     
  17. bernardgreen

    bernardgreen

    Joined:
    3 Nov 2006
    Messages:
    24,127
    Thanks Received:
    2,346
    Location:
    Bedfordshire
    Country:
    United Kingdom
    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.
     
Loading...

Share This Page