RE: Stepping up 120v - 240v - can the Hz be converted too?

["Nigel Giddings" <nigel@xxxxxxxxxxxxxx>]

Load on the Grid will affect frequency of the mains, however they do
have an obligation to keep mains synchronized clocks relatively
accurate, within 20 seconds at 0800 every day.



I had a long chat with the power engineer at a sewage farm open day 30
years ago... They produced much of their own power from methane and
sometimes disconnected themselves from the grid. They also sold excess
to the grid from time to time. He had 4 clocks that he had to monitor,
GMT, Site Time, Grid Time and a fourth showing the difference in
seconds. He could change the clocks on site (slightly) by disconnecting
from the grid and adjusting the frequency of the power he produced....



Some more info here



http://www.vf.utwente.nl/~ptdeboer/misc/mains.html



*	On short term (seconds to hours), several mechanisms are
employed that continuously try to keep the frequency as close as
possible to 50.0000 Hz, but that do not consider the phase (i.e., clock
error).
*	As long as the deviation between the true time and the time
indicated by a mains-driven clock is less than 20 seconds, observed at 8
o'clock in the morning, no further measures are taken.
*	When that deviation exceeds 20 seconds, a correction is
scheduled: during the next day (from midnight to midnight) frequency
regulators in the entire zone will be set to 10 mHz higher or lower than
the normal 50.0000 Hz. Ideally, this results in a correction of 17.28
seconds.
*	The above should normally keep the deviation within about 30
seconds. Only if the deviation exceeds 60 seconds are larger corrections
than 10 mHz allowed.





-----Original Message-----
From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
Of Richard (lists)
Sent: 02 January 2009 08:07
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Stepping up 120v - 240v - can the Hz be converted
too?



They make up for it offpeak, at least here in NZ,

Its not uncommon to see line powered clocks to drop back a couple of
mins
and then catch up again.

From: ukha_d@xxxxxxx <mailto:ukha_d%40yahoogroups.com>
[mailto:ukha_d@xxxxxxx
<mailto:ukha_d%40yahoogroups.com>
] On
Behalf Of
Mark Hindess
Sent: Friday, January 02, 2009 9:01 PM
To: ukha_d@xxxxxxx <mailto:ukha_d%40yahoogroups.com>
Subject: Re: [ukha_d] Stepping up 120v - 240v - can the Hz be converted
too?

On 2 January 2009 at 16:27, "Richard \(lists\)"
<rich_lists@xxxxxxx
<mailto:rich_lists%40richms.com>
<mailto:rich_lists%40richms.com>
> wrote:
>
> Replace the clock will be the cheapest thing you can do.

I agree.

I read somewhere that the frequency is reduced when there is high load
on
the grid. So even if you could fix it you'd have a clock that would run
slow during the ad breaks for popular tv shows. ;-)

I'm sure lots of people on this list are monitoring their power usage,
but
is anyone monitoring this?

I have a linev graph for my ups but I'm not sure this varies in a
similar
way.

-Mark.

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]


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