[ltp] Running with line power and no battery

[Joerg Bruehe]

Hi,

Henrique de Moraes Holschuh wrote:
> On Thu, 28 Feb 2008, Joerg Bruehe wrote:
>> [[...]]
>=20
>> I work from my home office, so any loss of power would affect running =
=20
>> machines, but I did not get any kind of UPS - that's my assessment of =
=20
>> the risk (for me !). I have heard from colleagues that short outages a=
re =20
>> frequent for them, because they are supplied via overhead wires which =
=20
>> are affected by wind, rain, ice, car accidents, ...
>=20
> Lack of power is not exactly the problem.  The issue is that when you p=
ower
> up a heavy load in an uncontrolled manner (i.e. when power returns to t=
he
> feeding branch that reaches your home), you get nasty variations on the=

> power feed (it is a n-degree system, where n > 2.  If you're lucky, you=
 get
> a single overshoot, but usually you get the full "ringing" effect that =
looks
> a lot like the one of a 2nd-degree undercompensated system).

Ok, I get what you mean, even though I lack the knowledge about the=20
details. I guess the strength of the effect depends on the supply=20
network topology, and here in Berlin (Germany) that is quite a dense=20
mesh of which I hope it will reduce them.  I may be wrong.

Are you (more) concerned about that effect on your power supply, or on=20
the notebook itself ?
(My main concern would have been the halt with files open, operations in =

progress etc - loss of data, file system damage, ...)

Regarding the power supply, I don't see how the battery in the laptop=20
could help these external electronics when the mains power goes wild.

Regarding the notebook, I assumed a power outage (without battery)=20
causes a shutoff so when the power returns it will be off.
If so, I thought there is no drain on the power supply (might help that=20
part), and no unstable DC reaching the internal components.

So, would the battery help with these problems, or do you mention them=20
as problems from power outages in addition to the machine halt ?

>=20
> That can kill electronics and high in-rush current devices like your
> refrigerator quite easily.  Especially with the kind of under-protected=
 crap
> we get for PSUs nowadays.

You live in Brasil ?  According to Wikipedia, your voltage is 120 V=20
then, while we are at 230 V. Accordingly, your currents would be higher=20
than ours for the same amount of power - I guess this will make these=20
effects much stronger for you than for me.

But I feel warned, thanks !

> If you're at home, when the power goes out you should open all circuit
> breakers.  [[...]]

Makes sense.  Until now, I had not opened the breakers, but most of my=20
devices have "old" switches which really break the power, or I have=20
switchable sockets between the wall outlet and the device(s) (especially =

for my PC and accessories) and would switch these off.


Regards,
J=F6rg

--=20
Joerg Bruehe  - persoenliche Aeusserung / speaking only for himself
mailto:joerg.bruehe@web.de