[time-nuts] Mains frequency

Jim Sanford wb4gcs at wb4gcs.org
Fri Mar 14 18:36:46 EDT 2014


Here's a url for the task-force report: 

I live near Pittsburgh, PA.  I think there is ZERO interconnection 
between PJM (grid operator we're on) and yours (forgot the name). 
INcidentally, if you read the report, you'll see some incompetence, bad 
decisions, and bad management in the 2003 blackout.  Only reason we 
didn't go dark here is because PJM saw what was happening in Cleveland 
and cut them off.  (Reminding me of one night on a certain ship in the 
late 70's, when one plant was getting unstable and the other plant cut 
them off -- half of ship went dark/lost propulsion, but not the whole ship!)

I do not remember when my clocks started acting up; it WAS after the 
announcement of the relaxation (or requested relaxation).

I have read about the NY blackout you describe in IEEE pubs (I'm a 
member of the power energy society) but don't remember much detail.

All the best,
wb4gcs at amat.org

On 3/13/2014 2:17 AM, Hal Murray wrote:
> [Context is maybe(?) withdrawing the proposal to stop keeping time on the US
> power line.]
> wb4gcs at wb4gcs.org said:
>> Since then, large amounts of generation (primarily coal) has been shut
>> down, so I was not at all surprised by the request.
>> I missed the announcement that the request was withdrawn, and actually
>> thought it had been approved and enacted -- all my line-frequency based
>> clocks are now erratic and not very accurate.
> I could easily be wrong on the withdrawing part.  I haven't seen any recent
> comments either way.
> Where are you located?  Did you notice when your clocks started acting
> erratic?  Do you have any solid data?
> I have 2 old, synchronous, line clocks (stove and clock-radio).  They seem to
> be working normally, but I don't pay a lot of attention to how accurate they
> are.
> I'm in Silicon Valley.  I do monitor the line with a typical time-nut setup.
> That's using the Linux PPS stuff to count cycles.  Here is an updated graph
> covering the last 12 weeks.
>    http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/Dec-2013.png
> The 0 on the left is arbitrary.  Peak-to-peak is 15 seconds.  So if I set my
> mechanical clock correctly, even at the worst time, it would still be within
> 15 seconds of correct.
> That's from counting cycles and dividing by 60.  A single cycle is a big
> event.  Off by one is easy to spot if you look at the right graph.  Here is a
> sample of a glitch:
>    http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-2014-Feb-20-pick.png
> I've only seen one event where a cycle was picked, none for dropped.  I might
> have missed something interesting.  Look at the longer graph above.  It's
> pretty clear I haven't missed a huge pattern either way.
> I saw one comment (don't remember where) that the problem was that the power
> companies had to file a lot of paperwork whenever the line frequency dipped
> below X.  (I don't remember the numbers.)  If they were running slow, (say
> targeting 59.98) to catch up for running too fast, and an event that dropped
> the frequency happened, it was much more likely to trigger the paperwork.
> (Seems like they should fix the paperwork-filing rules to allow for that case, but maybe it's more complicated than I can see.)
> ---------
>>    This is what initiated the 2003
>> blackout in parts of the US & Canada.  A utility had a paucity of  reactive
>> generation on a day with large reactive load, and one of its  generators
>> tripped on over-excitation to prevent damage to the generator  and voltage
>> regulator.  This initiated the cascading events that left  many in the dark.
>>   (The Joint US/Canada task force on that event is a  /fascinating/ read!)
> Do you have a URL?
> In the late 70's there was a big blackout in NYC.  I remember reading the IEEE article on it.  I don't remember any frequency graphs.  Did they archive that sort of data back then?  The deal was that an important line bringing power in to NYC was knocked out by lightning.  Power lines have several load capacities, depending on time.  Thus they can carry X forever, X+x for a half hour, and X+xx for 5 minutes.  A line from Long Island was carrying it's 5 minute rating for way more than 5 minutes.  Somebody in the control room had their thumb on the "shut up" button.  They knew that line was a critical resource, but they couldn't shift any load.  Eventually, it sagged enough to hit a tree.  Then that line when out and so did all of NYC.  (That's my memory from 35 years ago.)
> Blackouts:
>    http://en.wikipedia.org/wiki/Northeast_blackout_of_1965
>    http://en.wikipedia.org/wiki/New_York_City_blackout_of_1977
>    http://en.wikipedia.org/wiki/Northeast_blackout_of_2003
>    http://en.wikipedia.org/wiki/List_of_major_power_outages
> >From 1965:
> the same song recordings played at normal speed reveal that approximately six minutes before blackout the line frequency was 56 Hz, and just two minutes before the blackout that frequency dropped to 51 Hz.
> 51Hz ??!!  Wow.  It would be interesting to see that on a graph.

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