Protection for computers and other electronics

Re: Protection for computers and other electronics

I would guess that the possibility of lightening causing problems between grid and off-grid power is very similar...

If you are worried, you best bet is to make sure you make backups of everything as often as needed to prevent loss work...

The chances of a hard drive failing or viruses, or even just an oops (erased file, modifications that you can't undo, etc.), are probably more likely than a lightening strike.

Hard drives last ~2-7 years, and can fail at anytime. A lightening strike that takes out your computer/home electronics is probably a once or twice in a lifetime event (or even less) for most people. Having backups is good practice.

If you use an USB disk to back up your computer, it probably would not be a bad idea to only connect it (signal and a/c power) when you are actually making backups--if you leave it connected (on or off), the chances of a strike damaging your backup drive are probably higher.

-Bill

Re: Protection for computers and other electronics

I have not heard that MOV in surge protectors have problems with MSQW and SW inverters... As long as the peak voltage does not exceed that of a normal sine wave (~180 volts peak or so), there should no problems. It has been decades since I had a MSQW inverter on a scope--but the peak of a MSQW should actually be less than than of a normal sine wave in a utility main (Root Mean Square Power would require a sine wave to have a higher peak voltage to have the same RMS as a square wave--~1.41x higher for a sine wave vs a pure square wave with the same RMS voltage--IIRC).

MOV's are voltage dependent devices and harmonics (which don't add up to more than ~180+ volts peak) should not affect them at all (other than a small capacitive effect with the higher harmonics).

Have you seen the problem Mike?

-Bill

Re: Protection for computers and other electronics

Diodes (or any voltage dependent device--even switches) typically have problems with inductive loads...

When the current is interrupted to an inductor, the field will be begin to collapse in an attempt to keep the current flowing--dramatically increasing the voltage (a few volts can be inductively transformed into several hundred volts very easily) across the switch/transistor/etc...

That is why a (reversed biased) diode is placed across the coil terminals (in a DC circuit). When the field collapses, the diode shorts out the reverse voltage spike, protecting the switch/transistor from arcing.

Or, a capacitor can be placed across the contacts (like in an old car ignition system using points in a distributor)--it delays the voltage spike until the points are open far enough to prevent arcing.

Generally, it would frequency sensitive components (like inductors, capacitors, transformers, motors, and such) which will be most effected by the high frequency components present in a square wave.

-Bill