Hello
I have the cooler master v650s psu,
it's pluged into an inverter(in ups mode !) that is pluged into an AVR,
from time to time, the AC goes bad, and I'm not talking about high or low voltage, basically what happens is that the AC blinks really fast, and the reason is the Neutral line, there is a loose/bad contact in the main Neutral wire that is supplying the house, and this causes the AC to go up and down really fast that it looks like it's blinking,
and since the problem is with the Neutral line, no AC protection device detects the problem and passes the electricity to the pc.
this happened to me once and I was able to shutdown everything really fast.
today it happened again, I wasn't at home and when I returned I found that my unRAID server is off, turned the server on and thankfully it seems nothing bad happened to server.
I don't know the reason exact that it was off, did the inverter malfunction and didn't switch to battery mode or was it something else, but my question is,
do power supplies protect from such event ?, like will bad/blinking DC electricity be passed to the components if the main AC line has a problem like the mention above ?
I'm considering a small 650va online ups that is powered by the inverter to protect the server from such events, but will it really help ?

The neutral problem you describe can cause huge voltage transients (up to 240 volts AC in the US) which could easily burn out your power supply. A good UPS should help to protect against this, but the safest solution would be to hire a qualified electrician to repair the problem instead. Bad wiring in your house is a serious fire and safety hazard and represents a huge risk to yourself and your family.

PSU inside have a big capacitor, in some standard, it require provide at least 16ms power interruption hold time, this is some kind protection. If interruption more then 16ms, then problem would occur.

 

Besides, not all PSU like modified-sine-wave UPS. BTW you should test your UPS functional or not especially the battery condition.

AC in my country is 220-240v, psu is universal (110v-240v 50/60hz)
I have a multi plug adaptor with over/under voltage protection which will cut off the power if the voltage drops or rises above a configurable range, connected to it is an automatic voltage regulator which will also cut off the power if there is a big sudden change in the voltage and the inverter is connected to the AVR which serves as a final protection from voltage spikes, but all of this can't protect me from such problem because it's not with the voltage, it's the Neutral line.
the problem is not with the house itself, but with the Utility pole that supplies the house(I've seen the Utility pole's line wire throwing electric spikes when this happened) and yes it needs to be fixed ASAP.
PSU's have a 16ms hold up time, but does that mean if the AC is down for like 30ms (above the hold up time) but it's still very short period, will the PC turn off and then automatically turns on again ?
I remember that when I turn off and on the power socket really fast like within a second, the pc will turn off and then on again even if it's not configured to turn on after power failures.
that said, I only care about the hard drives, and as I understood from your comment, such thing will only hurt the psu and not components that are plugged into it.

1 hour ago, Benson said:

Besides, not all PSU like modified-sine-wave UPS. BTW you should test your UPS functional or not especially the battery condition.

it's labeled as pure sine wave(even though I know it's a lie, but it's good enough to not cause problems), it's functional and  battery is in good condition too.

15 hours ago, sadeq said:

I remember that when I turn off and on the power socket really fast like within a second, the pc will turn off and then on again even if it's not configured to turn on after power failures.

If you haven't set turn on after power failure, PC won't power up. I haven't idea if you got such founding.

 

Or you may check other power on setting, such wake on lan, wake on link too.

Edited December 12, 20187 yr by Benson

15 hours ago, sadeq said:

I understood from your comment, such thing will only hurt the psu and not components that are plugged into it. 

In ideal case, PSU DC side have different protection, such OVP, UVP, OLP etc (over v, under v, overload). But this not mean PSU won't fault and burn anything.

 

https://forums.unraid.net/topic/76290-hard-drives-not-getting-detected-after-a-psu-failure/

Edited December 12, 20187 yr by Benson

luckily my problem is different, it's not with over/under voltage but with the ground line.
I've just brought an online ups on top of the inverter which should help protect me from such problems in the future.