Lightning Question

quique
quique Solar Expert Posts: 259 ✭✭
in Solar Beginners Corner #1
This is not a solar or renewable energy topic per se but please bare with me.

We just had the first thunderstorm of the season and a lightning struck somewhere nearby.

I think the chronology was:

1). Milliseconds before the lightning, power dipped.
2). Lightning lit up the sky
3). Thunder was heard and by that time power was back to normal.

The dpi I refer to was the lights dimming and the AC slowing down.

My question is, what causes those dips in power?

I understand lightning strike on a tower or cables can cause voltage spikes. But why dips?
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #2
    Re: Lightning Question

    My first guess--Lightning is a DC current... Hit a power line and you create a DC current in the power system. AC transmission transformers are usually designed to limit current by saturating the core (limits maximum current). Throw a DC current into an AC transformer, they will generally saturate and limit their output current (short brownout).

    If the system does not "shunt" the power or open a breaker (they can be computer controlled and will try to reconnect after a trip a couple of times). That can also cause your quick power failures.

    Anyway, my first guesses.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #3
    Re: Lightning Question

    I should add another possible reason for a brown out--High voltage from the lightning creates a plasma from lightning strike line to ground (across an insulator, through insulation, etc.)--That plasma could have low enough resistance to short out one phase of an AC line (tripping breakers, browning out a phase, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: Lightning Question

    first explanation sounds better bill.
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  • brboyer
    brboyer Registered Users Posts: 3 ✭
    #5
    Re: Lightning Question

    Lightning strike on/near distribution line. The emergency breakers trip (and automatically re-close a couple seconds later) on the affected circuit. Customers on that circuit see it as a momentary outage, customers on other circuits may see a voltage sag due to the increased demands on the remainder of the system and the perhaps because of the 'increased distance' the power has to now flow.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: Lightning Question

    that sounds plausible too.
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  • quique
    quique Solar Expert Posts: 259 ✭✭
    #7
    Re: Lightning Question

    Just so y'all know, I learned tons just from thinking and reading about the subject!

    Found this:http://www.academia.edu/5738413/Electric_Power_Syatem_Basics_by_Steven_W.Blume

    Thx guys!

    Just wish there was an easier way to distinguish between transformers (all subtypes), breakers, reclosers, regulators etc.

    They all share any common features.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #8
    Re: Lightning Question

    From that document: "Suppose a lightning strike hits a distribution feeder’s “B” phase near the substation and causes a B-phase-to-ground fault. The ground overcurrent relay would sense the increase in ground current and instantaneously send a trip signal to that feeder’s breaker."

    So, that tends to sound like the plasma argument above is correct since the strike is temporarily grounding the phase.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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