Power surge

art_94

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Hello,
My wife and I just bought a new LCD tv and we lost power to it from a power surge....What do we need to prevent this from happening in the future?
 

westom

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Why do you think you had a surge? A surge is very high voltage. Power off is zero voltage. They could not be more different.

If your TV needs protection from a surge, then everything in that house needs that protection. Especially the one device most critical during a surge - smoke detectors.

Why is power off destructive to any electronics? It is not. Despite popular urban myths that define power off destructive ... total nonsense.

 

art_94

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your answer didnt help me much
 
If the power surge caused the TV to shut off and you just had to turn it back on again then you will need a power conditioner with battery backup as you would use with a PC. Check the wattage requirements which will be in the specification in the manual that came with the TV. This will also help if the TV was damaged by the surge and required repair or fuse replacement. If you are just trying to prevent damage from surges then by a good quality surge protector (not a cheap one that will not last long). All surge protectors wear out over time so find one that indicated that this is happening if you can.
 

westom

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Answers will only be as useful as information first provided. When AC power goes off, then power is lost to the LCD tv. When power comes back on, the tv works again. Is that what you want to prevent? Nothing in your post demonstates or even implies a surge existed.

If a tv does not operate, well, you never said that. Maybe 15 different reasons could explain that failure. Surge is only one and way down the list of possible suspects.

Define symptoms of that failure. If a surge existed, then define other 'what also must be damaged' appliances. Where and what they were also connected to. And other relevant facts.

If a tv has failed, then no magic box on its power cord will fix it.

Replies were only as useful as information first posted. Better replies also means numbers and other hard facts are provided.

 

anwaypasible

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if a power surge is a moment of higher electricity.. then what on earth is a spike?

i always thought 60hz of whatever amperage could have the amperage increased when the frequency drops below 60hz

like.. the lights will dim if there is fluctuation in the lines outside and the house gets hit with whatever is left from the change.
otherwise, if your power is 60hz at 500 amps .. and if it went to something like 50hz at 800 amps , you really shouldnt be able to see the lights brown out unless they rely heavily on the 60hz cycle.

since your electricity is 'tampered with'
you might as well buy a conditioner to boost the brown outs and prevent the voltage spikes from getting to the electronics.
but
you also need a battery backup for when the power goes out completely.
not only can it be really cool to have your electronics running while the electricity is out everywhere in the area.. it CAN prevent damage to your electronics.

there is no urban myth about yanking the plug from the electrical outlet and causing damage.
the truth is, it really doesnt matter unless the hardware is designed to 'discharge and go into sleep mode'
like.. if you have a CRT television that is on, shutting off the television with the power button might simply turn the electron gun off.. OR it could turn the elcectron gun off and activate a 'blow off valve' for the electricity that was previously going at full speed.

it depends on the power supply and the specifications of the pieces connected.
when you stop providing power, sometimes all of the pieces inside fight for the remaining electricity until it is all gone.
other times, the electricity is going full speed forward and has no place to 'release' the electricity.. this can bounce backwards in the opposite direction OR get totally forced to stay there in one spot.
if it stays in one spot, it could damage something with that piece (by heat or drying it up too fast or 'zapping' itself)
if the electricity travels backwards in the opposite direction, that is like the whole circuit seeing DOUBLE the voltage it is ment to.
this would obviously lead to premature failure since the stress levels for the circuit are twice as high.

like if the electron gun gets shut off.. the power supply to the electron gun DOES NOT have to shut off immediately.
you can switch on a relay that dumps all of the excess electricity into a bank of resistors to release the pressure safely.

ever wonder why many of the cheap CRT televisions make no noise when you turn them off except for the static on the screen?
and have you ever compared that noise to a $1,500 sony television that makes a click when you shut it off?
sometimes other brands will click when shut off if the screen is large enough.

its about allowing the excess electricity some place to go.
if you unplug it without turning it off, then the last piece in the chain will zap itself (and maybe some of that electricity goes backwards if the first piece is sloppy or 'easy going' )

it is just like a vehicles engine with a turbo.. you HAVE TO have a blowoff valve to release the air pressure when the rpms go down.
if you dont release the air pressure.. you are gonna put like 50 - 60 psi into the intake and the intake is gonna explode (or break a seal if the pressure isnt too high)

not all electronics need excess electricity to be 'relieved' its pressure.
but
dont think for a second that the electricity wont play 'hungy hungry hippo' when the electricity stops coming.
nothing you can really do about the electricity inside if there isnt a design to release it all.
since a power supply typically works on a 1:1 ratio of input to output (stepping up or stepping down the voltage aside)
if you kill the power from the input of a step up or step down transformer.. the electricity is going to stop on the first coil and the second coil will have nothing to suck up.

if you want to talk about nasty transformers... then there might be some electrical radiation from a magnet when the power is cut.. but that is what your power filters are for.
and if the radiation is going to kill the first or second coil wires (or the magnet itself) then the transformer is self-destructing without any help.


not all capacitors stay charged when the power is shut off.
the electricity can scatter like an army of ants.. or more violently, an army of roaches.
that is why there are quite a few electronics that have a delay when you turn them on.. the circuits inside are charging up.

one might think to put a bunch of light bulbs in parrallel with all of the capacitors and transistors, with a relay to turn the lightbulbs ability to shine off/on ... but that will ruin the slew rate of the circuit.
and even then.. the resistors dont always like to be fed lower voltage than what they are designed for.

this is a mention of how these pieces age FASTER.
because simply receiving their voltage and being there without voltage isnt anything out of the ordinary.
and this puts stress on the designers of the pieces.. since they know good and well that they could design a piece that actually 'resets' itself whenever the smaller voltage is applied.
and if you take away the 'reset' .. then the piece might die faster than it would if you left it alone.
lots of options to choose from.. either it will be seeing voltage differences when the power is shut off OR it wont see differences when the power is shut off.
things like capacitors, resistors, diodes, transisters.. these things usually see the voltage difference when the power is shut off.
if you buy a product that has these pieces inside that are ready and willing to be tortured like that.. then the piece of hardware might last for 15 - 20 years.
compared to a product that has pieces inside that ARE NOT ready and willing to be tortured like that.. and the hardware fails in 6 - 8 years. (although i would hope it is 8 - 10 years personally)


to say that the pieces on the circuit board dont care, that is insensitive of the person.
and to say that i am a liar is to say that i am over-sensitive.
a person who knows exactly what model number we are talking about might know the pieces inside are ready and willing to accept that type of torture.. and that person would say something like 'that product should be safe'
but
not everybody is going to talk about what they know because people might start begging for information.
and the person might have answers, with no time to be asked questions.
or
the person might not have all the answers for the many different electronic products on the market, and simply want to avoid a situation like 'i know this one.. but i dont know that one'

these people who do know, they usually get stalked and harassed by electronics enthusiasts, since their 'enthusiasm' takes over and they want their curiosity answered.

how many electronics have we seen fail over the last decade??
really ask yourself that question and answer it.
because i know the answer is 'a lot'
hundreds (maybe thousands) of CRT televisions have broken.. same thing with the LCD and plasma televisions.
motherboards
modems
printers
fax machines
amplifiers
receivers
and any of those causal designer 'toys' such as clocks and other department store electronics

these things have failed early for a lot of people.
even big name companies like comcast and directv or dish have seen their cable boxes fail early.

if everybody had power conditioners and battery backups.. then we would really know how bad the electronics industry has treated us when we give them our money.
but
since we dont have the power conditioners and battery backups.. it is all a guess as to whether it was dirty power from the outlet or a seriously inferior product because of junk components on the circuit board.
sure, you might be able to grab one and test it individually to learn if it is junk.. but us consumers cant do that on a wide scale based on reviews and complaint stories.
we dont have the insurance put in place to be angry.. since algebra still exists and we have not ruled out a variable.

this also means we should be careful choosing the power conditioner, since you dont want the device that is supposed to save your products from premature failure to actually be sending excessive voltage to the hardware.
that would be counter-productive.
 

richrom

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Westom has no real idea how to help on this level of a forum. Wetom assumes that the poster is an electrical specialist that can determine the difference between a surge and a fluctuation, or some other common household brown-out. So rather than provide and answer, he just spouts on about BS that most would not understand. Either post helpful info for the poster or just keep quiet.

" If a surge existed, then define other 'what also must be damaged' appliances."
Do you really think if the poster has a surge that went through the house and damaged other electrical components that he would be posting that type of question here? Seriously. That's like someone getting into a major car accident that totals his car, and then asking how to fix a scratch in the paint.

Other posters provided useable feedback, like line conditioning or better surge protectors. Perhaps you could start there and see if this helps the poster before you try to impress with your PHD in Electrical Engineering.
 
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