How? Neutral is only required to stabilise uneven phases, and is often a thinner conductor.
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10 years ago
Clamping voltage on surge protector?
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10 years ago
they conduct the charge previous to lightning, discouraging the main bolt from taking that path.
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10 years ago
The reality is that these surge protectors offer very little, if any, protection against lightning strikes. A lightning strike close by can kill your electronic equipment regardless of what protection you have. I regard them in the same league as expensive hi-fi interconnects or snake oil.
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10 years ago
Incoming neutral goes open circuit. If one phase happens to be heavily loaded and the other two very lightly loaded then the voltage on those approaches 415V.
Or, of course, the example you already gave of incorrect wiring.
John
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10 years ago
Except that equipment at comms sites and Radio and TV transmitting stations does survive year in year out;!...
The Ross Andrews lightning conductor!! allows you to use your audio system in any weather!, made of some unknown to science metal a snip at £3,000 a yard;!!..
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10 years ago
That's as may be, but they tend to have rather better quality protection on all their connections than a cheapie "surge protected" 13A strip with a tuppenny MOV in it.
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10 years ago
Perhaps I can interest you all in a new magnetic water softener!
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10 years ago
I once had a surge protected 13A plug, with a 13A fuse, powering an extension cord. Into that extension cord was plugged a UPS (among other things). Into the UPS was plugged a computer and a monitor, which I was using. I didn't notice anything had happened until the UPS bleeped to inform me the battery was almost empty (3 hours later - it had an extended battery). I then checked the surge plug, which had a brown indicator on it instead of white, to indicate it was expired. The 13A fuse had blown. No appliances were damaged, and I was drawing nowhere near 13A on that extension cord, so I can only guess the plug removed a surge, blew the fuse, and prevented the surge hitting any equipment. The plug was undamaged, didn't smell bad, just had a brown indicator.
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10 years ago
Those have considerably better design against damage from electrical storms. Nevertheless they are not immune to damage. Likewise aeroplanes. In a domestic situation it is quite common for large amounts of electronic equipment to be damaged by nearby lightnings strikes without there being any evidence of a direct strike on the equipment.
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10 years ago
Someone was wrong.
Andy
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10 years ago
He designed computer power supplies.
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10 years ago
They will of course go into conduction every half cycle, and quickly have a melt down or fire. But hey you know what you're doing.... apparently.
NT
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10 years ago
The peak equivalent obviously.
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10 years ago
No, they do sometimes dissipate a charge before it builds up to form a much bigger discharge;)...
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10 years ago
Can we have a vote on this, or even better a link to the correct answer?
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10 years ago
RMS=Root of the Mean Squared. It gives the equivalent of the DC for the purpose of calculating power usage etc.
It is the peak voltage x 0.707 = RMS voltage (but only for sine waves).
So if you have 650Vpeak, the RMS value will be 460V
Mains power 230 volts (RMS) peak value is 325 volts.
So the cable insulation has to stand 325 volts.
For square waves the factor is 0.5
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10 years ago
Voltages in AC are normally referenced to zero unless otherwise specified.
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10 years ago
No little bit of electronic bollix will resist a nearby lighning strike.
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10 years ago
All depends on how close the strike is. If you think some bit of electronic crap is going to divert the Megawatts of power in a near strike, you want your head looking. Buildings can be protected with lightning conductors, maybe 250mm squ conductor. Your litte fartbox is worthless in such a situation.
The only real protection is disconnection in these situations. ie pull the plugs (all of them) if you see lightning nearby.
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10 years ago
Maybe it depends how long the surge was. See my other post (reply to a reply to yours) where a room full of computers was fine when connected to two phases by mistake. Just the bulk capacitors in the PSUs blew. I've also accidentally connected a printer and a computer to 240V instead of 110V when the switch was incorrectly set at the back. Also I've seen about 10 computers with the switch set wrongly on purpose by kids. Just a bang and a new capacitor required. I would have expected the fuse or breaker to blow before the voltage got through to the equipment in your case though - the bulk capacitors go short circuit?
A fuse can carry four times it's rated current for an hour before it melts. MCBs are a bit better.
They are clumsy overcurrent devices, voltage makes no difference. In no way will they protect electronic devices. They are not anti-surge protectors.