Author Topic: Neutral line fault detector NFP-1801?  (Read 12895 times)

0 Members and 1 Guest are viewing this topic.

Offline Siwastaja

  • Super Contributor
  • ***
  • Posts: 9449
  • Country: fi
Re: Neutral line fault detector NFP-1801?
« Reply #25 on: January 27, 2023, 12:14:15 pm »
I have to visit Finland. Crazy, can you show some photos how this Finnish PEN looks like?
Maybe the phrasing on that website is odd, but here's nothing weird about it
There is. You live in Finland and you see that every day but believe me - we do not have such overhead designs elsewhere. I meant: How does such overhead line with phase conductors supported by PEN cable look like? Could you post an example photo?

Quote from: Caruna.fi
the PEN conductor, which is a metal cable that supports the phase conductors between poles.

https://mycourses.aalto.fi/pluginfile.php/1473286/mod_resource/content/3/S%C3%84HK%C3%96ENERGIAJ%C3%84RJESTELM%C3%84N%20RAKENNE%20JA%20OSAT.pdf
See page 9 for images

This is for low-voltage distribution, on countryside. More densely populated areas have been converted to underground cabling of course.
 
The following users thanked this post: Alti

Offline Alti

  • Frequent Contributor
  • **
  • Posts: 404
  • Country: 00
Re: Neutral line fault detector NFP-1801?
« Reply #26 on: January 27, 2023, 04:48:39 pm »
This is for low-voltage distribution, on countryside.
AMKA cables. Or Aerial Bundled Cable.
Overhead lines are popular of course but it is the first time I see a bare PEN conductor that serves as mechanical support for phase conductors.. I thought such cables have an additional steel strand that serves as mechanical support.

An AL+FE version of PEN.

And some bigclivedotcom YT:

« Last Edit: January 27, 2023, 05:53:58 pm by Alti »
 

Offline Siwastaja

  • Super Contributor
  • ***
  • Posts: 9449
  • Country: fi
Re: Neutral line fault detector NFP-1801?
« Reply #27 on: January 28, 2023, 07:40:16 am »
AMKA cables. Or Aerial Bundled Cable.

Looking at a datasheet for a cable used here, it says the conductors are just aluminum, but the supporting bare wire is aluminum alloy. So probably some alloy with better mechanical strength. Not going to beat steel, of course.

I would assume such bundle almost always breaks as a whole, making neutral faults rare (or last for only some milliseconds). But it's impossible to completely eliminate neutral wire from breaking as long as the wire exists.
 

Offline okaro

  • Newbie
  • Posts: 1
  • Country: fi
Re: Neutral line fault detector NFP-1801?
« Reply #28 on: January 11, 2024, 09:11:28 pm »
The stupid thing about it when it comes to EVSE regulation, is it's required in UK for single phase EVSEs, which disconnects the cars' chassis from PE. Of course that doesn't help with any devices in the house where suddenly PE became essentially a phase/live. If you were to put such a device in the panel for the entire house/unit, that would make more sense. There is added risk due to much crappier PE bonding now, since it goes through a relay back to the supply.

EVs are a large grounded item that is straight on the ground so the risk is seen as high. Also they are a new thing. It is easier to make requirements when people install new things than to to regulate afterwards. When you are inside bonding protects you from shocks between grounded items and metallic surfaces like taps. There are some 400 PEN-faults in the UK annually with some 40 injuries (electric shocks).
 

Offline excrucio

  • Newbie
  • Posts: 3
  • Country: hr
Re: Neutral line fault detector NFP-1801?
« Reply #29 on: January 01, 2025, 11:42:01 pm »
So, this is inside of it
https://youtu.be/kBxAjbUnYos?si=SDFH6r0xE856L2yl&t=440

Inductor...
What is principle behind it?
 

Offline f4eru

  • Super Contributor
  • ***
  • Posts: 1120
  • Country: 00
    • Chargehanger
Re: Neutral line fault detector NFP-1801?
« Reply #30 on: January 07, 2025, 07:16:40 pm »
Seems like an LC network, i.e defined impedance that is connected between neutral and PE ?
then it triggers an RCD if the neutral deviates from PE.
Works only of course if the defect is after the bonding point, or if the PE comes from a separate earth rod...

Could it be that the LC is tuned to 50Hz, so that normal sine does not pass, but HF/harmonics of DC will trigger the RCD ?
I would have expected more like a 25V VDR or so.


In any case, it's probably not nice, because injecting currents into the RCD can make it inefficient against it's original purpose....
« Last Edit: January 07, 2025, 07:23:27 pm by f4eru »
 

Offline excrucio

  • Newbie
  • Posts: 3
  • Country: hr
Re: Neutral line fault detector NFP-1801?
« Reply #31 on: January 07, 2025, 09:41:27 pm »
injecting currents into the RCD can make it inefficient against it's original purpose....
there is no current until it is N fault, and when it is it is not big. so rcd works as it is intended
 

Offline f4eru

  • Super Contributor
  • ***
  • Posts: 1120
  • Country: 00
    • Chargehanger
Re: Neutral line fault detector NFP-1801?
« Reply #32 on: January 09, 2025, 07:18:39 am »
not really. There are often a few volts between PE and N.
If it would trigger suddently, and then connect a resistor between L and PE, having the same effect as the RCD "Test" button, then I would agree that it does not affect the RCD.
« Last Edit: January 09, 2025, 07:20:59 am by f4eru »
 

Offline themadhippy

  • Super Contributor
  • ***
  • Posts: 3311
  • Country: gb
Re: Neutral line fault detector NFP-1801?
« Reply #33 on: January 09, 2025, 10:50:29 am »
Quote
If it would trigger suddently, and then connect a resistor between L and PE, having the same effect as the RCD "Test" button
thats not how the test button is wired as the PE  rarely goes anywhere near the rcd,its wired across the incoming side and  the output side
 

Offline uer166

  • Super Contributor
  • ***
  • Posts: 1030
  • Country: us
Re: Neutral line fault detector NFP-1801?
« Reply #34 on: January 09, 2025, 09:29:50 pm »
not really. There are often a few volts between PE and N.
If it would trigger suddently, and then connect a resistor between L and PE, having the same effect as the RCD "Test" button, then I would agree that it does not affect the RCD.

And to be clear: triggering a upstream RCCB/RCBO via leakage to PE as a safety function is specifically prohibited by most product and installation standards both in EU and NA, it's a janky and dangerous way to go about it.
If you need a remote trip, use a shunt trip attached to a breaker or something, don't be cheap about it.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf