Scarey Shit

[dnar]

This morning I awoke to find that the light globe in our entrance hall had exploded (it was left on overnight). The glass on the floor was all black/silver like the filament had vapourised big time. Curious indeed.

I then went upstairs to my lab, were I have 10 computers running 24x7. My main machines are all powered from a UPS - they were all humming away nicely. I have another 7 machines that are less-critical and some are a new office network (Linux) that is being installed this week, these machines were all dead. Looks like Mr Power Company has some explaining to do......

 

[Neo]

bummer dude, that is not a good sign at all. none of the 7 will fire up at all? hope you have a small deductable on your homeowners ins.

 

[dnar]

bummer dude, that is not a good sign at all. none of the 7 will fire up at all? hope you have a small deductable on your homeowners ins.

Bringing them up now, looks like all systems are fine. Luckily, the new office systems run Ext3 filesystem, the Ext2 systems will of course requiring a long fsck.

I am lucky, no power supply failures so far, just blown internal PSU fuses. How much voltage does it take for a 240V light globe to explode though? I have never seen anything like this in my short 38 years on this rock....

 

[dnar]

I will be most pi33ed if my 486 Linux system is fuX0r3d....

 

[fury]

OUCH! Sorry to hear about the surge.

 

[dnar]

Right, all systems back crunching at 100% again.

Damage bill:

1 x 60W ES light bulb
7 x glass fuses
1 x set of under wear

Even some of the glass fuses were shattered. I know that hte MV to LV transformers in our power grid are not capable of much overvoltage (before core saturation) so I wonder if we lost our neutral for a bit? That would result in one of the 240V single phase legs reaching a potential max of 440V.

Very glad the UPS survived. We lost our HiFi VCR and computer UPS at Christmas when power was restored following a black out, this is just getting too frequent. Funny thing is, the local power company (we have only one) are a customer of mine. I setup and configure the comms (GSM modems) for their remote power quality monitoring instruments, time I had a word to these guys about my woes.

 

[fury]

@ 1 set of underwear



Glad to hear the systems are still going.

Are the fuses and bulb expensive?

 

[dnar]

@ 1 set of underwear



Glad to hear the systems are still going.

Are the fuses and bulb expensive?

No.

It has always been my experience, that an expensive semiconductor will always blow to before the fuse though. I am very lucky.

What a mess though. Glass fuses suck. I have fitted sand filled HRC fuses, much better, much faster acting as a result of the quenching action too.

 

[fury]

Are sand-filled fuses a viable option if there are frequent power problems in a trailer? If so, where would one get them?

 

[dnar]

Are sand-filled fuses a viable option if there are frequent power problems in a trailer? If so, where would one get them?

The idea behind HRC fuses, is that traditional glass fuses tend to arc when the fuse blows, and therefore allow current flow while the fuse blows/arcs. HRC fuses quickly quench the arc and therefore provide more protection. They are generally always used in building switchboards (although breakers are more common these days).

You can find HRC fuses anywere that sells electronic components or electical contractor suppliers. They are easy to spot, the body is generally ceramic and white/cream in colour.

 

[fury]

Cool. Do they have any other obvious benefits besides preventing current from flowing while the fuse arcs?

Like, are they generally safer or stronger, or less easily blown or anything like that?

 

[dnar]

Cool. Do they have any other obvious benefits besides preventing current from flowing while the fuse arcs?

Like, are they generally safer or stronger, or less easily blown or anything like that?

I find them to be generally higher quality, glass fuses tend to be cheap crud (unless made by bussman or any other name brand). One advantage - they dont shatter into a million peices as i have experienced today!

BTW - glass "exposed element" fuses are mostly a problem when protecting inductive loads - motors and transformers etc.

 

[fury]

Thanks! I'll check into them the next time we have a fuse blowing problem.