Can a safety switch be tripped by an event external to the house?

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
At about 4:15am yesterday morning my UPSs went crazy, indicating loss
of power. When I rang the electricity company they informed me that
there was a known problem in nearby areas, but not specifically at the
substation that my property hangs off. The operator suggested I check
the safety switch at the board before they sent someone out, and to my
surprise it had popped off.

Is this a common thing? A bad coincidence or did an issue at another
substation somehow cause the switch to trip?

Next time there's an outage I'll check the safety switch BEFORE
running around like a mad chook shutting everything down. :)

Re: Can a safety switch be tripped by an event external to the house?
Forgot to add, one reason I'm curious about this is because I
eventually plan to install a residential generator here - a natural
gas powered backup gen (permanently wired) that kicks in when mains
fails. In this instance I don't think it would have provided power
continuity since the safety switch had tripped, and I doubt the backup
generator would be wired to bypass this...

Re: Can a safety switch be tripped by an event external to the house?

Quoted text here. Click to load it

  I haven't seen it a problem here, the only time our internal breaker has
tripped is when something internal has done it.

  My UPS trips here by far more often than it did, and now that I'm seeing a
fault with it, the server comes down every time there's a brief outage.

  Should get to fixing that some day...
--
Linux Registered User # 302622
<http://counter.li.org

Re: Can a safety switch be tripped by an event external to the house?
ive got UPS that did this, it was leaking voltage
back in the mains system, solved it with another
relay added

Quoted text here. Click to load it



Re: Can a safety switch be tripped by an event external to the house?

Quoted text here. Click to load it

Err, generators do not provide power continuity. Their role is to take
over the power provision from an approriate level of UPS. You'll need to
make sure thatyour UPS can now provide any extra needed time for the
generator to come up to speed and sync properly and that the UPS can hand
over(?) to the generator.

Unless it is a big bickies situation, you are probably best just going for
automated shutdown on the ups, then restart on the generator. There is
nothing like the smell of cooked batteies on Monday morning to know that
you are going to have techs in again this week to work out what went
wrong this time and to repair the damage, yet again.


Re: Can a safety switch be tripped by an event external to the house?
Quoted text here. Click to load it

By "power continuity" I meant that my equipment would not die as soon
as mains power disappeared - there's a UPS on all of the important
stuff that was going for about 10-15 mins before I shut everything
down manually. This is not a large or critical installation but it is
used for 24/7 internet business purposes so "continuity" is reasonably
important. Just like a RAID array allows fairly normal operation to
continue if a hard drive fails, rather than absolute downtime until it
is replaced.

BTW, there's little point having a backup gen if the house wiring is
isolated by a popped safety switch. ;)

Re: Can a safety switch be tripped by an event external to the house?

 
Quoted text here. Click to load it

Err, didn't you put your office onto a separate circuit?
Makes it easier to swap it over to the genie, aka get a changeover switch
installed on that circuit only.


Re: Can a safety switch be tripped by an event external to the house?

Quoted text here. Click to load it

Do you have a brand and model worked out?
Or just an idea?

Given that multi-hour outages are becoming more regular here and we have
the gas mains in the street, it is interesting if I can find the business
income to justify it.

Re: Can a safety switch be tripped by an event external to the house?
Quoted text here. Click to load it

I didn't have a specific model in mind, but I was looking at Kohler
Power Systems as the brand.

Heard from a USA acquaintance that a 35kW setup cost about $USD30k
fully installed. I wouldn't be looking to power the entire house so
that level would be overkill. (Would a typical residence even consume
anywhere near that much concurrently??)

Re: Can a safety switch be tripped by an event external to the house?

Quoted text here. Click to load it

If it is an emergency power plant, then you have to look at exactly what
you really need to keep running. If it is servers/internet presence for
a business, then that is one thing, and should be reasonably economic to
do.

OTOH, if you've trained the family such that they think the air con and
ice maker  should keep running no matter what, then you'll probably need it.

The problem I can see is that is if you have anything significant, you
are basically sitting on a residential gas feed and it is going to
experience peakish demand about the same time you see want a big
generator running. Yep, most of our neighbours strike up the BBQ when the
electric power goes out. Newer homes will have those BBQs on the gas feed.

I had looked at the bottom end stuff from Advanced Power a while ago, but
that was a significant whack to convert a petrol to LPG at the time.
Frankly, we could get away with a basic genie outside the window approach
even now, but I'd change my mind if it started to happen every
quarter<mutter, bound to with privatisation>.

If (when X) I was going to be spending $30K, then I'd look at grid
attached solar(rebates, reducing current ongoing expenses) with onsite
batteries option. If the grid goes off, then I'd have the batteries to
feed the UPSs for the computers(*), inverters, etc.

Then I would add the gas generator, although, it might be better to think
more along the lines of "battery charger" in that case.

(*) I am currently looking at mini-box.com dongles that allow you to run
computers directly off batteries. They claim 90% & recharging lead acid
is about 90%, so 80%+ efficency as a full time feed now(no UPSs).
Really need to get out the DMM and see just what the real efficency of my
current computer power supplies are.


Re: Can a safety switch be tripped by an event external to the house?


Quoted text here. Click to load it

Possible. I've seen enough electronic device suddenly rattle/shake/roll
from something and spurious signals on the powerline seems a common
likely.

It is an answer that you are never going to know unless you hae a full
time wave logger on the power supply to log wafeform.

Or, it could just have been a cockie having a shit in a warm place {:-0.


Re: Can a safety switch be tripped by an event external to the house?

Quoted text here. Click to load it

Bad power can't cause an earth current to flow on its own. One of your
devices had to have leaked the current, and even if the power is bad a
device shouldn't do this unless you have somehow gotten very excessive
voltage, like over 400V.

I have seen dust/insects/spiders in PC's do this, light that fail can do it.
Once I had a PC near a window and someone watering the garden accidently
sprayed water though it and into the PSU shorting mains to earth.
Condenstation will do this also. Any thing with a capacitor to earth can do
it when the caps leak/fail/open and then it can appear as if nothing is
wrong, as most caps to earth are just to filter noise.

One way i often see is when the 'chassis' (usually just exposed screws) of a
2 pin DC plug pack device touch the chassis of a 3 pin device. The 2pin
devices can have a cap between a DC terminal and chassis, which then goes to
the next chassis and to earth, causing an earth leakage current to flow as
the cap changes its charge.



Re: Can a safety switch be tripped by an event external to the house?
Quoted text here. Click to load it
[...]

This is my main concern, that it *was* a coincidence, and there's
possibly an issue which will rear its head again. I have 5 UPSs, 7
PCs, assorted networking equipment and an air conditioner in the
office. Of course there's also all of the other sundry electrical
equipment in our house.

It was 4:15am so it's unlikely that the switch was tripped by a one-
off event caused by a human (or feline - they were asleep on the bed
with me)

Of note is that the power dipped twice again during the day, so
perhaps the substation wasn't quite so isolated.

Re: Can a safety switch be tripped by an event external to the house?
Quoted text here. Click to load it

Possible. After renovations, our safety switch would trip
every few days, always at exactly 7:58 AM. I searched for
the problem, and when I was convinced it wasn't in our
house, argued with the power company about it. Initially
they denied it and said I should replace the safety switch
because it was too sensitive, but after I pointed out that
it can't possibly be *time* sensitive, they agreed to
replace it for me.

The contractors they sent said that they'd replaced hundreds,
and it was caused by the power factor correction capacitor
banks being switched in at that time, in preparation for
industry firing up for the day. The new safety switch has
never false triggered since.

It doesn't help you work out what actually happened at 4:15am,
but it indicates that something on the power line could have
tripped it, and that getting a different one might make it
less likely to happen again.

Clifford Heath.

Site Timeline