General > General Technical Chat

did you ever see a plasma ball fly out of a power strip?

<< < (7/7)

coppercone2:
i heard nothing I thought it was just something happening with the regulation, I assume wind took out tree branches because it was really windy, this is unrelated to any rain, thunder or lightning as far as I know.

I don't know what happens I assume they up the voltage because of losses and it shoots up when load is disconnected by a tree?

SilverSolder:

--- Quote from: coppercone2 on March 17, 2021, 07:50:41 pm ---i heard nothing I thought it was just something happening with the regulation, I assume wind took out tree branches because it was really windy, this is unrelated to any rain, thunder or lightning as far as I know.

I don't know what happens I assume they up the voltage because of losses and it shoots up when load is disconnected by a tree?

--- End quote ---

I guess it's possible to get one heck of an inductive "smack" out of those big transformers, in the right (wrong) circumstances?

Berni:

--- Quote from: coppercone2 on March 17, 2021, 07:50:41 pm ---i heard nothing I thought it was just something happening with the regulation, I assume wind took out tree branches because it was really windy, this is unrelated to any rain, thunder or lightning as far as I know.

I don't know what happens I assume they up the voltage because of losses and it shoots up when load is disconnected by a tree?

--- End quote ---

Over here we run 3 phase with neutral on power poles. So if a tree happens to break the neutral line first then the voltage on the least loaded phase is going to shoot up.

But MOVs are known to spontaneously combust here and there. As they experience surges they gradually deteriorate, eventually they deteriorate enough to start conducting slightly at the rated voltage too, making them get hot. Eventually it deteriorates enough where it just start conducting properly at rated voltage, making an enormous amount of power dissipate in them. This makes them smoke, catch fire or explode.

coppercone2:
3 power strips and a clock in 1 day is no coincidence, and I don't think they can explode that bad as the picture shows normally? not sure though

Berni:

--- Quote from: coppercone2 on March 18, 2021, 06:20:37 am ---3 power strips and a clock in 1 day is no coincidence, and I don't think they can explode that bad as the picture shows normally? not sure though

--- End quote ---

Yeah perhaps the quality of the power coming into your house is particularly bad. Try measuring it with a dataloging multimeter.

We had undervoltage problems at out house, we didn't really notice since everything worked fine. But then dad got a solar array installed on the roof and every so often the inverter would trip out into error about mains voltage. So i hooked up a multimeter to the phase it was complaining about the most and logged it over a few days. Turns out the mains voltage was sometimes briefly dropping to 180V, but other times was the proper 230V, sometimes staying at 200V for periods etc... Obviously this was not okay, we emailed the plot to the power company, they came around and installed there own dataloger on all of the phases and came to the same conclusion that this is not good. Eventually they came around and we let them run a new underground cable along our property to give this area of the street its own feed from the transformer.

Opposite effects can happen with overvoltage if the power company decides to 'fix' such a problem by turning the transformer up to a higher voltage tap. This may get the people on the end of the line the proper voltage but the people close to the transformer might be getting too much. Fast transients can also come trough the lines since they might not get swallowed by the transformer due to inductance at high frequency.

But blowing up is an intended mode of operation for a MOV. They are designed to absorb power surges so that they don't blow up something more valuable. If the surge is small enough that might only result in the MOV getting hot from the energy. If the surge is large then the MOV can absorb so much power that it burns up or even explodes, but even then it is still doing its job in turning the energy of the power surge into thermal energy (or light and sound in the extreme cases), this is energy that could have otherwise continued on and blew up a power supply. Just that these large surges physically destroy the MOV so it needs to be replaced.

I repaired things before where lightning hit it. I open it up and find the fuse blown and the MOVs looking like charcoal. I place a incandescent lamp across the fuse to see if the thing still works enough to be worth attempting to fix. Sometimes they are shorted or make a fireworks show when voltage is applied. But often it just needs a new fuse and MOVs. They have taken the sacrifice for protecting the rest of the device.

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod