Inside a Power Bar After a Surge, and How MOVs Work

Рет қаралды 4,750

Күн бұрын

Got this used power bar. Noticed a rattle. Looks like it's seen some lightning. This is why you check used things. Nothing that can't be fixed. Also a little explanation of how MOVs work in protection equipment and a little rant about how I think a lot of surge protector ratings are misleading at best.
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Пікірлер: 33

@UnforeseenLife 2 жыл бұрын

I've never actually seen the aftermath of a power surge through a power bar. Super informative!

@manletopia4801 7 ай бұрын

I have in real time it was a multiday surge the fluorescent lights were buzzing really loud blew out fridge compressor I was playing video games Infront of TV heard electrical crackling sounds behind TV and all my electronics cut off immediately smelled burnt electronic smell when i poked my head behind TV opened up all my surge protectors all the MOVs were completely charred all of our electronics were saved the fridge wasn't on a protector

@WizardTim 2 жыл бұрын

I’ve seen surge protector companies claiming that PCB trace spark gaps should be included in the joules rating, that can easily inflate the value. I wish companies would be more transparent about it, often times marketing will just say “surge protected” with no joules rating and modern products have non-reversable screws so taking them apart for inspection is very annoying and often destructive.

@gorak9000 2 жыл бұрын

I'm sure it's pure marketing wank. How are you going to measure how many joules a random surge was to prove it was under the limit? Has anyone ever actually recovered any money from any of the claims of "$xxx of protected equipment guarantee"? I'm sure you need the original receipt, and the original packaging (and probably the poops you took immediately before and after buying the power bar) to even begin to think about collecting (which everyone throws out 5 seconds after you plug the power bar in), and then even if by some chance you actually had that, they would just say "well, the surge was greater than YYYY joules" and how could you ever disprove their claim?

@scotscheideman9800 2 жыл бұрын

Size has NOTHING to do with clamping or varistor voltage in MOV's The numbers on the side indicates voltage and for example - 14mm(medium size that blew up) and 20mm(the 3 new ones you're handling) Bourns MOV's are Both available with The Same Varistor Voltages from 18 to 1800 volts. Size combined with voltage rating does have a direct bearing on the Joule rating . An example of the numbering system - 20D241K- 20D=20mmDiameter-- 241=240volt nominal Varistor Voltage--K=10% Tolerance. Depending on the voltage rating, 20D MOV's can have from 11Joule to 626Joule rating. At the same voltage ratings, a 20D has about 1.6 times higher Joule rating than the same voltage 14D. The crazy ratings seen on many new units is curious indeed, I think they have switched to IsoMOV's which are an "all in one" MOV and GDT which creates a much longer life component. These do not have the same Joule rating but a Max Peak Current rating. No doubt some form of "Creative Mathematics" by the manufacturer's marketing dept. has somehow converted it to Joules , very optimisticly!!!

@roostydoo2 2 жыл бұрын

I've never actually seen the aftermath of a surge nice video keep it up!

@manletopia4801 7 ай бұрын

@victorcoss2600 2 жыл бұрын

So is a grounded outlet required for surge suppression or not? If the MOV's are placed on each combination of the 3 legs, then shouldn't surge suppression still work? I was under the impression you have no device safety without a proper ground, but you can get human safety by adding a GFCI. I am in a 1960s home which has no grounding, so a lot of my UPS' and power strips show wire fault or the protection light won't light up. But I have heard they make special surge suppressors that'll use Neutral. Maybe I'm confused, if MOV's absorb excess voltage/spikes instead of sending said excess to ground.

@TheUbuntuGuy 2 жыл бұрын

Nothing is sent to ground, that's a different type of fault. A MOV between line and neutral will still provide surge protection without grounding.

@victorcoss2600 2 жыл бұрын

@@TheUbuntuGuy Interesting, I always thought the MOV's send the excess to ground, which is the whole point of having a ground, that and a backup for if you lose neutral.

@gorak9000 2 жыл бұрын

@@victorcoss2600 The MOV basically turns into a short when a voltage over its threshold is reached. The MOV sacrifices itself to shunt the excessive voltage. If it's a MOV from line to neutral, then it just shorts line to neutral to try to dissipate the voltage spike. Neutral is connected to ground at your breaker panel or service entrance anyway, but "ground" is never meant to carry current (for safety reasons) whereas neutral is always carrying current in most circumstances.

@scotscheideman9800 2 жыл бұрын

@@TheUbuntuGuy Most decent surge protectors now have MOV's that span Hot-Neutral, Hot-Ground and Neutral -Ground, so YES in some cases they can send to ground. Transients can come in on any of the 3 lines though most come in on Hot and can be shorted to neutral by the MOV.

@assertivekarma1909 2 жыл бұрын

Testing of MOV's would have been a bonus, I have a box of larger what appear to be MOV's but they don't have identifying info. They were likely industrial.

@gorak9000 2 жыл бұрын

They're not all gray - I have that exact same power bar in off-white (cream? beige?) color. Actually thinking about it, I think the MOV might've blown up in mine too - it exploded once when I turned it on, but it worked fine after (though maybe it was the switch itself that crapped out, and I took it out and soldered the wires together permanently and covered the hole where the switch used to be by wrapping electrical tape around the whole thing - don't exactly remember now) - now I'm curious. Next time I find that power bar, I'm going to check!

@windisk1112 2 жыл бұрын

Make sure you paint over that "burned in carbon". The "carbon" left behind from blown MOVs is conductive and can cause all sorts of problems.

@majorkramer Жыл бұрын

Stupid question. What is the rail metal composed of?

@Phil-D83 8 ай бұрын

Can they be rebuilt with new movs?

@nomusicrc 2 жыл бұрын

It amazes me that the power strip still works after these have been blown I would think that it would stop it from working because you no longer have surge protection

@docferringer Жыл бұрын

Yeah, that's why a good surge protector has a light on it to indicate if there is a surge. There is just no other way to tell unless the blown varistor and the lightning damage the outer casing. I like power strips with an all metal body for this reason. If you have anything flammable around your power strip you want to be sure that any internal shorts stay internal and don't melt their way onto the carpet.