On Tue, 5 Oct 2004 19:19:34 -0700 'clevere' wasted 5 lines of text
to spew in newsgroup: alt.home.repair
It's the same plug. Voltage will fluctuate throughout the day. The
only constant the power company promises 100% accuracy is *frequency*,
which in North America is 60 Hz.
Remove the 'snails' from my email
Frequency from the power company should not change under load (it might if
using a generator that bogs down). For inductive loads peak current may
be out of phase with peak voltage, but both are the same frequency, just
the peaks may be offset from each other.
I am a retired EE who worked on large scale mainframes for over 30
years. I used to monitor incoming AC for the site with power monitor.
I have seen freq. drop(not much half to 1 Hz or so), voltage spikes,
sags, blanking out, etc. all the time. Theorywise yes, but in real life,
no, it fluctuates little bit.
If you don't believe me, go rent a power monitor(now it's all digitally
done) and watch it for a few days and see what's going on yourself.
Well, nothing on this green earth is exact and this includes power line
Back about 30 years ago I was involved with some rotating machinery that was
involved in a timing function. I was given the task to find out what the
tolerance on the line frequency was. After a bunch of calls to Boston Edison
I finally got connected to their engineering department. I was told what the
tolerance was at that time for the frequency. (You know I can't remember now
so don't ask) I was also told that a major factor in the Great Northeast
Blackout in 1965 was the fact that as portions of the grid came under
overload, the generators would go out of sync and the grid just collapsed
like a house of cards.
Typically, the system loses cycles over the course of the day. It is caught
up at night when the load is low.If that did not happen, the standard
electric clocks would eventually be wrong.
Damn, I've been wondering about that for years. I finally had a chance to
fulfill my quest for knowledge and now it too, is gone. Think, Charlie.
Relax your mind and try to remember that day. Recall the papers you wrote.
We're all counting on you so don't let us down.
[original post is likely clipped to save bandwidth]
On Wed, 6 Oct 2004 11:49:38 -0400, "Charlie Bress"
The specific reason is some generators went of phase and were not
disconnected but the protection equipment.
The entire grid must be in sync (including phase) or it fries itself. The
original post I replied to claimed local voltage drop will cause frequency
changes. That would take down he grid every time.
Personal home page - http://gogood.com
gerry misspelled in my email address to confuse robots
Agreed.The slightest 'out of phase in one section of a large connected
network with several generating input points would cause massive fault
currents. Protection equipment should then disconnect that section within
What happened during the 'Great blackout' of a few years ago IIRC was that a
section of transmission line (In Ohio?) developed a fault and the protection
equipment did not at first disconnect it. Also when it was disconnected
extra power suddenly took unexpected alternative paths through the US and
Canada which caused overloads that disconnected other transmission lines in
the US and Canada. Some humans reacted correctly and isolated their areas
others did not; no overall plan. So, how many was it? Over 9 million people
without power for hours?
I happen to live in an area where we are not connected to the 'North
American Electricity network' although our power system is completely
standard at 60 hertz and, despite our at times severe weather, very
But I do recall, in the mid-late 1950s, a peninsula area of one of our
provinces which was separately fed by diesel generators, continually
overloaded these did 'run slow'. I remember seeing frequency meters at 58
cycles! (Which is about 3% slow!). But since that peninsula network was not
connected to anything outside there was no problem, except that electric
clocks ran slow (So nobody bought them and it was before the era of cheap
battery clocks). Also anything on a record player could sound a little odd!
Anyway a little bit of history and comment.
Way back when, before the the electronics age, the local "powerhouses"
used to have a large syncronous motor electric clock and a big old
"Regulator" style pendulum clock (with second hands on them) next to
each other on the wall.
They'd manually tweak the speed of the steam engines driving the
generators to keep the electric clock synchronized with the mechanical one.
They used to use light bulbs connected between the outputs of a loaded
generator and an idling one to get the phases matched to each other.
They'd close the switch to put the idling generator "on line" when the
bulbs remained dark for a few seconds.
My name is Jeff Wisnia and I approved this message....
Jeff, we are contemporaries. In 1953-54 or about I visited a Boston Edison
generating facility. No pendulum clock for these folks. Up on the wall was a
big analog clock. Nearby was a WWV monitor. The story we got was that
starting at midnight they brought the analog clock into agreement with WWV.
If you wanted to set your clock at home the recommendation was for about
3am. Don't wait until you get up on the morning, water heaters and stoves
coming on line to start the day would drag the line down again.
Regards Charlie EE56 xK1ICK
Assuming this is a serious question, yes. Welders are not picky about
the supply voltage, and even if they were 120V and 110V (and 117v) are
just different terminology for exactly the same thing.
Hope this helps,
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