Lightning Arresotr For Solar Boat

Discussion in 'OnBoard Electronics & Controls' started by ashwinnaique, Sep 25, 2015.

  1. BertKu
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    BertKu Senior Member

    Fanie that is exactly why it is happening. First at all, let me take a statement back. My apology to you. "Some form of regulation is needed on long term, probably for people like you." It could be taken as offensive. let me rephrase it. "Some form of regulation is needed on long term, probably for people like me, who may forget that DC at voltages greater than 45 Volt is deadly).

    Fanie people don't understand. Lightning must be re-routed, not blocked or compressed, but RE-ROUTED. If that is done, what you have mentioned would not have happened, if the correct conductive re-routing was applied.

    I am on the way to Cape Town, to sort my other problems out. You have to argue it out with others.
    Bert
     
  2. Fanie
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    Fanie Fanie

    Instead of looking for regulation to comply to certain requirements, rather gain the knowledge so you won't be dependent on regulation to force you to do the right thing.

    Spikes and other noise can easily be generated in any electrical and electronic circuitry. It is for the designer to decide what is required to make it fail-safe. Spike suppression is supposed to be standard.

    But to re-route lightning ? I'm not so sure. An average lightning is said to have enough power to power a city for a year. The power company cannot even re-route power properly, how the heck are sailors going to re-route a lightning bolt ? ! Lightning is unpredictable, we cannot force it to go where we want.

    Most masts are conductive, and even if you have a composite mast, it has to have wiring in it and in most cases stays that are also conductive. None of that will carry or re-route a lightning strike.

    Radio amateurs use a grounded metal plate they fit against the wall where the antenna wire goes through to the radio to short a high voltage spike to ground, but nothing will save you from a lightning strike. It only save you from inductive spikes in case of a remote strike.

    Furthermore, lightning can occur either from ground to up, or from up there to the ground. I would rather build a small FET circuit using a P and an N cha FET with a polarity plate on either gate to warn you when a static buildup is taking place. And you do not need clouds to get a lightning strike.

    This is where carbon fishing rods work well, when you are in a high static buildup the carbon will begin to shock you and the message is get the hell away from there if you don't want a permanent hair fixture like Einstein or RHP's avatar.

    If you consider the amount of lightning strikes even in cities, I tell you, the Creator must be very, very, very patient considering the few people struck by lightning.
     
  3. BertKu
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    BertKu Senior Member

    You see Fanie, that most of the people don't understand lightning. You yourself should go to the CSIR and talk to the engineers there who have been or are dealing with lightning research. What I don't know, whether that division is still there. I am now 75 and that was a long time ago that I was involved with them. But lightning does not change, although it may have become more severe. Bert
     
  4. BertKu
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    BertKu Senior Member

    To put it in simple terms. If the lightning strikes and it has to find a way to dump its energy into a badly conductive conducting metal. The energy is then in full over that distance the lightning has to crawl through it. In the process you demolish everything.

    If you re-direct and re-route the lightning, you have for that distance a short circuit and the energy over that short distance is low. What is left over is the heat from the air coming towards you. That is easier to protect from.

    This is in simply terms what has to be done. You don't put an arrestor over the protecting equipment, you re-route it to earth. How better your earth is how less damage or better said no damage. But people put arrestors and varistors over something and all what happen is that the energy explodes in that little device. Instead you must re-route the spikes, energy, lightning to earth.
    Bert
     
    Last edited: Sep 28, 2015
  5. gonzo
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    gonzo Senior Member

    What do you do about the electromagnetic field? That is what usually destroys electronics.
     
  6. BertKu
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    BertKu Senior Member

    I am driving to Cape Town and quickly stopped to give you a reply. I give you a NON practical, and crazy example. However you will better understand what is happening. Here is that crazy BertKu who has 8 thick fat copper wires from the top of his mast going down to the waterline. ll in all 0.0001 Ohm (1mOhm) Also here is Fanie the boer who is perfect and has beautiful stainless steel wires down to the side of the boat and it is 10 Ohm. Now both will have a lightning strike of up to 40 bursts of each 50.000 Ampere for 1 second.
    Bert will survive, he may be deaf and shocked and Fanie is dead human burned flash. The 50.000 Ampere is already been measured lately higher, but we stick to both 50.000 Ampere. Bert top of the Mast is 50.000 x 1 mOhm = 50 Volt potential and the current will equal give the same intensiveness strength field, but the strike is not jumping all over the place to find other shortcuts and also not high enough to burn bert. But he is deaf.
    Fanie has 50.000 Ampere x 10 Ohm has a voltage potential from top of his mast to the waterline of 500.000 Volt. If you want to argue with a dead man called Ohm, that is fine with me, but the law of Ohm will basically apply. I will be back on Thursday.
    Bert
    Bert
     
  7. powerabout
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    powerabout Senior Member

    std on commercial kit which I why I think it survives hits much better than pleasure boat stuff.
    The other reason IMHO is all the 24v power on a ship is floating so -24v is not the hull
    I hear B&G actually suggest now to use 12-12 power supplies for instruments to isolate them.
     
  8. powerabout
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    powerabout Senior Member

    My experience seeing lightning hits and misses here in Asia where we get plenty;
    the cloud above you is looking for a good ground therefore you are inviting it with good earthing surely?
    the tallest mast doesnt always get hit.
    ( I know a keel stepped rig 30' higher than all the boats around in and for several years never got hit when all other around it did.)
    I've never seen it do the same thing twice.
    Some boats seem to be magnets for it yet others not.
    Carbons masts seem to attract it slightly more than others
    Some yachts will suffer from a lightning strike a mile away.
     
  9. philSweet
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    philSweet Senior Member

    Radio guys know all about this stuff. They hang junk on towers, some of which average more than one strike per day. You want to get the voltage surge to a number below 100V at every place anything penetrates the hull. Antennas, cable, phone, shore power, waterline, nav lights, radar, helm station harness, courtesy lighting, sound systems, solar and wind sources, outlets for portable devices, winches, capstans, spotlights and horns. Everything. And there is a gadget for all of them. After that, its all about design and workmanship within the hull. Don't bundle comm with AC with DC with circuits that penetrate the hull with helm with engine harness. Use a subpanel for circuits that are likely to see user mods such as sound and lighting and security and portable devices, and protect that well. Low voltage DC requires special devices.

    Air gaps, wire "drip loops", and properly engineered conduits (waveguides) can get the surge down to spec at the point of penetration. After that, MOVs and PPTCs and selective isolation can be used per equipment manufacture's recommendation. Now all you need is a boat mechanic who knows how to do all this. Large vessels should try to collect the ESAs in a stout metal vault.

    And visually inspect the shore power transformer for a working arrestor (one that's still in one piece). If the transformer's high side isn't protected, you are going to get trampled by shore power surges beyond what you can choke.
     
  10. powerabout
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    powerabout Senior Member

    the drilling rig I worked on had a double hit on the derrick on both DGPS antenna's
    ran down the cables, jumped the arrestors and blew up the receivers then stopped.
    Melted the heavy coax
     
  11. Fanie
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    Fanie Fanie

    PhilSweet has the right idea.

    If you add spike suppressors incorrectly it actually assist in frying the application. Some items are not sensitive, like a battery and does not need protection. One mistake many make is to seek the distribution box and install the suppression there. It does not help any, and in fact it assist the induction Gonzo refers to to induce a large voltage on the wire, because the spike suppressor now help to close the loop so the induction can gain in potential in the loop... or coil, even though it is just through one wire loop.

    To suppress say a radio - the suppressor devices should be fitted right by or close to where the wires goes into the radio. The suppressor device should be between + and - an well as from + to the metal enclosure and from - to the metal enclosure - almost as if you are dealing with three phase power. The negative power may or may not be connected to the enclosure, if it is you need to protect only between + and GND/Neg. The idea is to prevent any part or wire to raise above the max supply voltage.

    There are different types of suppressors.

    On phone lines in the plug they put a spark arrestor, you saw them. It has two plates like a capacitor, usually in a vacuum or some gas that allows a spark without a flame. If the lightning strike, the plates short the incoming voltage, the initial gap creates an ion path that enhances flow. The gap determine the spark voltage.

    Then you get MOV's (Metal Oxide Varistor) which has a gradual clamping characteristic at the breakdown voltage. These usually goes short circuit if totally overpowered and they get too hot, as a result will trip the supply. Had a couple that went open circuit also. You get really big ones but they are $$$

    Not to be confused wit MOF's. A mof is a scew bloke.

    One also get transzorbs. These can be uni or bi-polar. On DC one would use uni-polar ones. These devices are the fastest and they have a more precise clamping voltage like a zener diode. Zener diodes are far too slow to clamp most spikes, so they made these devices and they are really fast. In the "zener" direction, the transzorb will clamp at say 16V, if the polarity is reversed due to the induction, the transzorb will work like a diode and short the reverse induction at around <1V. You can parallel these devices for more power as well.

    Lastly just simple ultra fast diodes between any wires will clamp (conduct) reverse polarity spikes.

    The spark arrestor is good for general purpose ie where a wire comes from outside and is not connected to anything sensitive.
    For electronic equipment I prefer the transzorbs. If you have multiple protections on one conductor set, their abilities are parallelled, but, never the less do no underestimate lightning.
    You could add some MOV's in the distribution box just to help keep the spikes at a more controllable level.

    Now when you installed your spike suppression it is not the end, no sorry. You are going to have to accept a bit of responsibility for your stuff, because as long as there are closed loops, ie wiring connected from the battery to the spike suppression where a loop is closed, induction can take place that can still fry the application if the devices capabilities are exceeded. A switch can open the loop, hence disconnecting the equipment. A pain to switch things off, but it may help.

    Ideally you want an open circuit so that current cannot flow, the devices then only have to handle static voltage, which are much easier suppressed without current. You should always keep one wire, usually the negative, connected to the rest of the electrical system, because if it is floating, it may be pushed many many thousands of volts above anything else and can make a lightning strike all by itself !

    One example if this is I had a friend (passed away) who had a very nice time with the wife, so just with his socks on he went into the lounge to fetch the glasses on top of his TV cabinet to pour them a drink. As he reached up for the glasses, he got one big surprise as mr pecker discharged the sock's static build up to the TV :eek:

    His spike suppression held up because they had kids later on, and no, I wasn't there, he told me. And in much more detail I did here. If he had a wire through all his activities ;) connected to his *snif* and to the TV ground, the incident would not have occurred. Keep this in mind next time you have plans, and if she wants to know what the roll of wire is for, tell her you'll show her. Just make SURE you connect that wire to EARTH, ok, GROUND :D

    Like Powerabout said, nothing helps for a direct hit. A bit like connecting that wire end to live mains and the earth leakage doesn't work...
     
  12. Fanie
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    Fanie Fanie

    I'm not much for complicate wiring, looms and these spider webs most people spin their boats with circuit breakers and fancy stuff.... I've seen wiring jobs where the back and forth wiring probably weighed and cost more than the hull :rolleyes: I simply use a pos and neg "buz bar" or thick set of wires and run them through the length of the boat and well apart so them getting near each other is unlikely. Every few meters you can put a MOV or two to keep the difference in check.

    If you do run these wires side by side, where you make a connection, open the insulation one more left from the other so you do not have bare connections that align that can be shorted together.

    Where ever I want to install something, I simply connect the application there, and that applications suppression will be at that light or radio or what ever. There is no easier way to do wiring and fault finding is simple, and wires are short. I like to use poly or multi-fuses with an LED (and resistor) over the device. IF a short or over current occurs, the LED will light up when the poly or multi fuse goes open circuit to indicate a problem, and it does not affect the supply.

    These poly or multi fuses goes hot and almost open circuit when over-current occurs, then regulates the quiescent current with temperature until the over current is resolved, it cools down and return to it's low impedance state. No fiddling for fuses, playing with trip switches, no 5 or 6mm screw fuse replacements ;)

    To prevent dips in power over a length of wire ie where a fridge motor switches on drawing a surge current, an easy solution is to connect a capacitor to the fridge's wires. When the motor starts up, the capacitor will supply the surge power and the line voltage does not get affected much. A good rule of thumb is at least 1000uF (or more) per amp drawed for the surge, and if you want better regulation, use a low-ESR cap(s) instead of an electrolytic(s). Lo-ESR caps have a lower internal resistance hence regulate more rigid. It works similar to what supercaps does when you start a large engine with a small battery. It cranks the engine longer and faster than the big battery could without the caps.
     
  13. Fanie
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    Fanie Fanie

    The supercap works because the starter battery has an internal resistance. When you crank the engine the start current is like a short which causes the battery voltage to momentary drop low, this causes losses and you lose torque. Every time the brushes switches over to a new coil, you get a similar effect.

    When you add the supercap, the impedance or internal resistance of the cap is lower, and it hence does not allow the battery voltage to drop as low. The starter hence turns faster because the voltage is higher, and the battery does not take the many hard knocks when it gets shorted momentary and supply a more smooth current. This allows a smaller battery with a supercap to outperform a larger battery without a cap. The battery life is hence also prolonged.

    Sorry, I'm off on a tangent here, just wanted to mention to let you okes know we electronic okes have our ducks in a row. Now we're just waiting for the composite blokes and the rest to come up to speed so we can have ultra light, dirt cheap, super strong and lightning fast boats as well :p

    Well, the micro's we use run in the megs already, you okes are still fiddling with km/hr and knots, ancient stuff :D
     
  14. BertKu
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    BertKu Senior Member

    That is indeed a good question.

    Referring to my quick answer along the road to Cape Town. I am back, came earlier home, too much rain in the Cape and have some time to answer your question.

    The way I see it is as follows.
    For ”Fanie” solution, I have none. The Voltage potential is so high 500.000 Volt and the lightning strike will jump all over the place. I cannot predict how. Also because of the quite high resistance between top of the mast and the waterline is so great, that it will take “quite some time” to travel and therefore the magnetic field is equal as high as in the version of BertKu, but there we have a different controlled situation and the impact is much less by BertKu. Let me explain this. Because of the resistance only being 1 milliOhm the electrons flow faster from top of the mast to the waterline. (or from waterline to the top of the mast, it depends a strike from earth to cloud or from cloud to earth) Also it is spread over 6 copper cables, while Fanie has only one top quality stainless steel line. Therefore the impact is much less. Probably a few hundred times less by BertKu also because the field of those combined 6 are spread over those 6 copper lines. Over and above we will have some kind of a Faraday cage effect, which also have a reduced impact. Look Gonzo, I know it is a crazy example and no boat builder will ever use copper cables on his boat, but it shows you the difference between surviving a lightning strike and being dead flesh after the strike. Trust that this explains your question. Bert
     

  15. BertKu
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    BertKu Senior Member

    Hi Powerabout.
    You actual answer your own observations you have. A lightning strike WILL travel via the easiest and lowest resistance to earth or from earth to the clouds. Therefore indeed, if the tallest building has a “worst” connection to earth then the lower building, I can guarantee you that the lightning strike will hit the lower building. Let’s now analyse your examples and observations you have noted.

    For that highest constructed top of the boat above the waterline, which never has been hit, the “easy” connection is not present. Probably they don’t use much metal or lots of cabling high up or has no electrical connection from top to the waterline. Now you would say, you see, you see, I am not earth my mast to the waterline. Much safer. Yes, until the boat is wet and has salt deposits on the deck and all over the place and suddenly the lightning strike discover that this is the best route to go. It will then blow your boat to pieces, because of the heat, electromagnetic field and the high electrical resistance to the waterline, which just does all kinds of unpredictable destruction. Therefore as explained in example BertKu, it is much better to have a boat electrical controlled and you can predict what the most likely outcome is.

    Now you’re other observations. The one boat gets hit, the other not. Where they exactly the same electrical connected to the waterline? Probably not. As explained above, a lightning strike will travel the easiest, lowest resistance to earth or visa versa. Bert
     
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