[GTALUG] Dirty Power and Wi Fi Far field effect

[phiscock at ee.ryerson.ca]

> On Fri, Mar 13, 2015 at 08:24:38AM -0400, Russell Reiter wrote:
>> I live close to the exhibition grounds which is near to one of the
>> city's
>> major grid switches. For example, they were testing the new streetcars,
>> the
>> ones with three sections for navigating tight turns and they browned us
>> down to (I assume) 50hz. This was visible as all the lights dimmed and
>> the
>> streetcar appeared to navigate the loop a short time later. As I don't
>> have
>> ups I had powered down my tower. The next time I powered up the breaker
>> in
>> the power supply tripped and when I reset it and booted, my 1.5v agp
>> video
>> card was toasted, at least I hope its the card and not elsewhere on the
>> bus.
>
> Changing the frequency of the power grid is VERY hard.  Dropping the
> voltage (which is a brownout) is easy.
>
Yeah, I agree. Frequency isn't likely to change. It depends on the rate of
rotation of massive generators in the Adam Beck generating station, for
one thing. And the whole system is locked together, as Lennart points out.

If you have access to the fuse or circuit box, I'd recommend measuring the
voltage at that point, then at the hair dryer outlet. There might be a
marginal connection somewhere that is dropping the voltage. Don't open up
the distribution box unless you are an electrician, electrical engineer or
immortal. There are lethal voltages and currents inside.

War story: Years ago I worked one summer as the effects guy at the Red
Barn Theatre in Jackson's Point. We had a three phase lighting board and
the power coming into the barn was two phase. So I checked with my power
engineering colleague and he confirmed it was OK to put two phases of the
lighting board on one side of the power and one phase on the other side,
and then to be a bit careful about the loading.

This worked well all through the rehearsal period. Then, at the opening
night reception, where everyone is in formal wear and eating tiny pieces
of fish, all of sudden every light in the place goes out. Of course,
everyone looks at me. So I go down to the distribution box with my
voltmeter, trailed by about 10 people, and measure the power at the entry
point, before the master switch and fuses. No input power. So I say 'Not
our problem, the Hydro is down.' Of course, nobody believes me and there
is some mutinous muttering. So I go down to the road to see if I can see
anything and in the distance, I can see flashing red lights. Turns out
some drunk had taken out a hydro pole. Fortunately, the Hydro guys had it
back up and running in a matter of minutes.

That was a nervous few minutes...

P.



-- 
Peter Hiscocks
Syscomp Electronic Design Limited, Toronto
http://www.syscompdesign.com
USB Oscilloscope and Waveform Generator
647-839-0325