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Load monitoring for new Extension power cables

Discussion in 'Power Electronics' started by cardom54, Jul 27, 2018.

  1. cardom54

    cardom54

    6
    0
    Apr 3, 2018
    Hello, According to the extension power cable with specifications of 16 amps power cable 14m height 1.5 mm with 110V with plug of trailing socket which I am using with high speed drillers, sometimes I have face some power load issues, and to measure these load variation, I was thinking to use cheaper and better embedded solution which consist of Raspberry Pi and AC current monitoring controller board https://store.ncd.io/product/8-chan...20-amp-ac-current-monitor-with-i2c-interface/ rather than heavy PLC services.
    With some good search I was able to find out some hardware which will be useful but still I need to know about the functionality with which I ll be able to get the desired value I need to know, Any suggestion I f someone have worked or working on this kind solution will be much helpful.
     
  2. kellys_eye

    kellys_eye

    4,286
    1,146
    Jun 25, 2010
    If you know the load, the voltage and the distance to/from source to load you don't need to 'monitor' anything. You can calculate the MINIMUM cable specifications for the permitted volt-drop.

    Protect the cable using the appropriate circuit breaker (with RCD for 'people protection') and that's all you have to do.

    Monitoring those values may give you a set of figures but it won't affect the end result of the cable you have to choose/use for the application.
     
  3. WHONOES

    WHONOES

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    123
    May 20, 2017
    Increase the cable cross section to reduce its resistance. Get some that has a current carry capacity that is double the expected load.
     
  4. kellys_eye

    kellys_eye

    4,286
    1,146
    Jun 25, 2010
    Why?

    If the cable is correctly rated (which it should be) then the volt drop 'should' be acceptable at any load - else you're overloading the machine on the end of the cable anyway - not a good thing.
     
  5. WHONOES

    WHONOES

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    May 20, 2017
    Kellys_eye.
    It's never good practise to use a cable, or anything else for that matter, at its design limits. Equipment running at 110V is always going to draw more current than or (UK) 230V system and requires larger cable to cope.
     
  6. kellys_eye

    kellys_eye

    4,286
    1,146
    Jun 25, 2010
    The specification for all (properly installed) cables accounts for any load within the design specification and there is no reason to 'extend' that spec unless you are deliberately abusing it.

    Design spec can accommodate intermittent use and continuous use but they will always include the required protection.

    The correct cable should be used from the outset and as per my previous post, if it has been specc'd there is no reason to monitor current - especially since, if properly FUSED as well as specc'd, the cable cannot be overloaded under any circumstance.

    Having said that...( :D ) there's no accounting for those that use extension cables under load and whilst still wrapped on the transport reel!!!! This is an invite to problems but a properly designed/specc'd transport reel will also include a thermal cut-out as well.
     
  7. kellys_eye

    kellys_eye

    4,286
    1,146
    Jun 25, 2010
    The values stated by the OP are as per typical extension leads available across the market:

    https://www.toolstop.co.uk/defender-e85111-extension-lead-16a-1.5mm-14-metres-yellow-110v-p79648

    The site transformer/distribution unit should, of course, be fitted with a 16A breaker. If via a site transformer then RCD is not strictly required (the secondary of these transformers being under the required voltage limits (i.e. 55V-0-55V with the 0V grounded) so the maximum potential anyone can reach under exposed wiring conditions is 55V - but, personally, I'd fit an RCD anyway.
     
  8. WHONOES

    WHONOES

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    May 20, 2017
  9. Bluejets

    Bluejets

    3,429
    693
    Oct 5, 2014
    Link not working for some reason.

    By site, I'm assuming construction site.
    Just for a side note, in Aus, the lead must be used on a safety switch/ breaker or combo unit.
    Leads cannot extend further than 30 ft /10m unless and additional portable safety switch is used.
    None of us leckys could ever work that one out but there ya go.

    Of course most applications are single phase extensions and there is almost a book written on additional rulings.

    I also cannot see any reason to have to go over the rated size or the use of any "monitoring" unit.
    One of the additional rulings is the single phase lead must be at least 15A and the insulation heavy duty.

    As the leads terminate in a plug/socket arrangement at the sub-boards, the outlet in these instances is protected by a 20a breaker/safety switch combo whether the outlet is 10A or 15A ....same same.

    Of course there is a standard curve requirement for the breaker.
     
  10. WHONOES

    WHONOES

    639
    123
    May 20, 2017
    Just re-tried SAB-Cable link on post #8 and it worked fine.
     
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