×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Power-grid experiment (1 year)

Power-grid experiment (1 year)

RE: Power-grid experiment (1 year)

The only clocks which will be affected are those which rely on the grid frequency. As far as I know that limits it to the types using synchronous motors, or possibly some vibrating element if any such device exists. The standard clocks which use quartz crystals won't be affected - the author is talking out of his arse when he suggests that ".... wall clocks and those on ovens and coffeemakers — anything that flashes "12:00" when it loses power — may be just a bit off every second, and that error can grow with time". They're quartz types with no battery back up. Makes for a good story though. smile

It's an interesting idea though, and I'll be looking for a more technically sound report if this goes ahead. It certainly does cost a fair bit of money to maintain the frequency at nominal value.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Power-grid experiment (1 year)

I really don't know of which I speak, but It seems strange that in the days prior to "digital", maintinaing "time" was just something that was done.  Pre sunrise, the dispatcher starting asking for MWs to get slightly ahead of the load, ie a little fast.  then as the day came to end, back down to minimun and wait through the night with the system a little slow.


my quick research into the AP news story was that the official "time correction" operation period was going to be less rigorous.  I was looking to see if the "experiment" had any thing to do with the actual generator's frequency respnse since my current peeve is after a life time of working mechanical linkage and hydraulic pistons to have the best responding governor possible, only to have it replaced with a computer that has programed dead band.

I ponder this as I try to read and comment on a bid spec derived by the utilities digital group to replace an OEM anolog EHC STG system.  makes me sick

RE: Power-grid experiment (1 year)

I suppose the thinking behind this experiment is a normal step in the spread of "Fuzzy Logic".
 

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Power-grid experiment (1 year)

Quote:

"Is anyone using the grid to keep track of time?" McClelland said. "Let's see if anyone complains if we eliminate it."
Good strategy.... try it and see what happens.  

=====================================
(2B)+(2B)'  ?

RE: Power-grid experiment (1 year)

Hi Scotty. I was surprised to find that my digital alarm clock did not keep time properly when in construction camps powered by diesel generators.
I guess they saved the cost of a crystal by counting cycles.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Power-grid experiment (1 year)

I remember the days of 2 clocks on the control board.  One was driven by the system, the other not.  I can't remember the interval, but occasionally, the operator would compare the two and adjust the system frequency accordingly.

That was way before I got my ME degree, and now thinking back, I have to wonder what the gage accuracy of the independent clock was.

rmw

RE: Power-grid experiment (1 year)

here is the proposal by nerc for abondoning time correction
http://www.nerc.com/files/Final_BAL-004_NOPR_Comments.pdf
I like the comment that requiring utilities to run above frequency to compensated for the time they ran below freq added "wear and tear".  I just wonder if they then allow the lower of the frequency to allow allow the system to carry more load without increasing generation

I never saw the dual clock, but my one and only visit to the "dispatcher" when begining with GE, I recall a large nixie tube display
 
google "henry warren master clock" for the history

RE: Power-grid experiment (1 year)

"I remember the days of 2 clocks on the control board.  One was driven by the system, the other not.  I can't remember the interval, but occasionally, the operator would compare the two and adjust the system frequency accordingly."

We still have those two clocks (digital clocks now).  There's also a display of the number of seconds difference, which the system operator uses to increase decrease the system frequency.

And for the record, when the frequency clock drifted and we lost about 15 minutes over Easter weekend last year, a number of people did notice.

RE: Power-grid experiment (1 year)

I don't get the 'apocalypse now' scenario. In India, our frequency excursion is about 49 to 51 Hz and my washing machine/microwave/alarm clock and other such knickknacks haven't started to walk by themselves.

Yet.

Muthu
www.edison.co.in

RE: Power-grid experiment (1 year)

Hi Bill - that really is taking cost-saving to the extreme!
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Power-grid experiment (1 year)

I did buy the cheapest clock on the shelf, so I guess the cost cutting worked for them. grin
Hi mgtrp. Sounds like an independent grid. Where in the world are you?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Power-grid experiment (1 year)

cost savings is correct.
If you have already sold those under frequency MWs, why generate the extra MWs just to make the total count of cycles correct at the end of the day.

If any manufactoring process was varied due to operating while under frequency, wouldn't a similar variance occur durring the correction period.

and for those anitiquated devices that use grid frequency as their time regulation, they need to step into the digital age.  Just throw those devices away like with anolog TV and "cash for clunkers".  this should be a stimulus for the economy ;)

RE: Power-grid experiment (1 year)

Yes to the independent grid, and in the Yukon.  Although slightly less independent as of last Thursday after our Northern and Southern independent grids were linked together, giving us close to 1000 km of high voltage transmission line transporting less than 60 MW about the territory.

If NERC wanted to see the effects of wandering frequency in North America, we'd be a good place for a trial.  Not that we could keep our frequency within the 59.95 - 60.05 Hz band that they seem to be talking about....

RE: Power-grid experiment (1 year)

(OP)
mgtrp;  Do you have anything to do with that building full of Cats on Dugas St in Dawson?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Power-grid experiment (1 year)

A little.

RE: Power-grid experiment (1 year)

I loved my time in the Yukon but wussed out at 40 and 50 below.
Do they still have the old diesel standby at Carmacks? I remember a transmission line outage in Carmacks in the early 70's. The old diesel came on as back-up. The frequency and voltage were both below any spec you care to name. We were in the restaurant watching the fluorescent light fixtures cycle off and on on their thermal protection. The low voltage and low frequency was causing the ballasts to overheat and trip the thermal protectors. At any one time about one third of the light fixtures were off. A somewhat unique load shedding process. No complaints though. Any power was better than no power.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Power-grid experiment (1 year)

The Carmacks diesel is owned by the local distribution company, not my company, but there's still one there... whether it's the same one as you had in the early 70's, I'm not sure.

RE: Power-grid experiment (1 year)

The NERC reference to saving "wear and tear" made me laugh.  If they are really worried about wear and tear, they should also shut down all the wind turbines.  They are causing some actual wear and tear.


 

David Castor
www.cvoes.com

RE: Power-grid experiment (1 year)

I've noticed that while my battery backed up digital (display) alarm clocks do not flash 12:00 after an outage, they will drift a considerable amount during that short outage. I conclude they continue to use the power frequency for accuracy. I predict there will be complaints.
Nearly every electrical appliance you buy now seems to include a clock whether a timing function is needed by the device or not. Do all these "convenience clocks" have quartz crystals? I'm guessing that like waross, they bought the cheapest displays they could find for a function no one looked closely at prior to the experiment.    

RE: Power-grid experiment (1 year)

Some of these use a ceramic resonator instead of a quartz crystal - I think to make it less expensive.

Some of the most inaccurate local oscillators used for keeping time that I've come across have been on protective relays.

I've done some work at a mill that often operates in island mode.  They have two clocks and claim their local clock keeps better time than the clock running off the grid - I didn't argue with them.  

I like my "Atomic" clock that receives radio signals from WWV in Fort Collins.

dpc

David Castor
www.cvoes.com

RE: Power-grid experiment (1 year)

I find it frustrating that I can pick up a cheap watch for £1- on the Sunday market which keeps better time than the (un)realtime clock in my PC, the one in the multi-function protection relays (very true dpc!), or the variable speed drives. More to the point, it makes me wonder about where else the costs have been cut in these products.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Power-grid experiment (1 year)

for ScottyUK.

Not only how cheap are the components, what about the button-type batteries that one finds often on internal boards on protection relays and other microprocessor type equipment- what happens when these batteries eventually go dead?  Are then the programming and settings gone to relay-heaven (long after the guarantee period is up, or the OEM no longer exists....) In todays fast-track world of youthful innovation and short-term foresight, are we not in for some ugly surprises down the road (years?) when,  one fine day, it all begins to fail and fall apart, system by system...

If power station control and protection as implemented today, are no more reliable or lifetimed as have been computer operating systems and hardware, (over the last decade or two), we are indeed in for some interesting times ahead.

Not to mention an EMP event...

rasevskii





 

RE: Power-grid experiment (1 year)

I have seen relays that lose there settings with the loss of power, but also many that use eeproms.

The comments about cheep clocks in devices reminds me of what I was told in lab class. The test power supply is a power supply. Not a highly accurate volt meter. If you want to know the voltage, use a highly accurate voltmeter.

RE: Power-grid experiment (1 year)

rasevskii,

I doubt we will see any of the modern relays still in service seventy years from now. There are quite a few electro-mechanical relays on the UK's network which date back to the 1940s. I wonder how many are even older and still in service?
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Power-grid experiment (1 year)

(OP)
Welcome to my world.. Probably 1/2 of all machine tools die ONLY because of a dead $3 coin cell.  A typical machining center has probably 400 parameters programmed into it defining torques, speeds, limits, etc.,etc.  Those parameters all evaporate and the company is gone or they don't support that model anymore.  It's really sad.

Keith Cress
kcress - http://www.flaminsystems.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources