pulses over the mains voltage system

[mic-d]

When I'm laying there awake in the wee hours, as I do from time to time and the ceiling fan is on, I hear signals through it. Now before you say I'm what I mean is I can hear pulses that alter the tone of the fan that happen exactly on the hour, maybe the half hour too. eg, one pulse, two pulses, three pulses, six pulses, five pulses, two pulses. Kind of like morse code, only there is no short/long. What's this for?

Cheers
Michael

[NCArcher]

That's the Supply Authority either switching your off peak on or off, or reading your meter or using your broadband connection. Well maybe not the last one. Or performing switching operations or any number of other things that they don't have to leave the office for anymore.

[tea lady]

Now you'll have us all lying there in the night listening.

Wonder if they go on during the day? Could be why your light globes sare blowing if it is littlw power surges. .

[joe greiner]

Periodic correction of mains frequency, to ensure "accurate" time display of clocks using synchronous motors, and reliable speeds of other motors. More modern generators may count pulses more frequently, e.g. every minute, so the corrections are less noticeable.

Early television sets assumed mains frequency to set the picture framing rate, but 'twas found unreliable enough to require local pulsing in the set itself.

Just a wild guess, of course.

Cheers,
Joe

[mic-d]

Periodic correction of mains frequency, to ensure "accurate" time display of clocks using synchronous motors, and reliable speeds of other motors. More modern generators may count pulses more frequently, e.g. every minute, so the corrections are less noticeable.

Early television sets assumed mains frequency to set the picture framing rate, but 'twas found unreliable enough to require local pulsing in the set itself.

Just a wild guess, of course.

Cheers,
Joe

I was with you right up 'til you said periodic.
CHeers
Michael

[SPIRIT]

yes they are talking to you , there are other dimension's and maybe the only way they can contact us is though surging the power supply

[tea lady]

Periodic correction of mains frequency, to ensure "accurate" time display of clocks using synchronous motors, and reliable speeds of other motors. More modern generators may count pulses more frequently, e.g. every minute, so the corrections are less noticeable.

Early television sets assumed mains frequency to set the picture framing rate, but 'twas found unreliable enough to require local pulsing in the set itself.

Just a wild guess, of course.

Cheers,
Joe

"hmm" May explain why my digital clock is always wrong. but I have never heard of this. (which I guess doesn't mean much. But I WAS once a telecom technician apprentice and this sort of thing was never mentioned. )

Does it happen right ON THE HOUR? Weird.

[mic-d]

"hmm" May explain why my digital clock is always wrong. but I have never heard of this. (which I guess doesn't mean much. But I WAS once a telecom technician apprentice and this sort of thing was never mentioned. )

Does it happen right ON THE HOUR? Weird.

Yep, right on the hour, perhaps you will hear them through the potter's wheel

Cheers
Michael

Sleep well!

[tea lady]

Maybe we could all go out and look at the power board as it comes up to.......(. Is that the time? B(&%#% computers. Just a time vortex, I'm off too bed. )We've got a digital power board. I don't know how much info you could see on the things. Like what the actual voltage is, or what the true frequency is. another Might have a look at it myself tommorrow.

'night. :zzz:

[joe greiner]

See http://en.wikipedia.org/wiki/Utility_frequency

Prowl down to "Stability." I was mistaken about more frequent correction. Hey, I said it was just a wild guess, didn't I?

Joe

[Ashore]

The truth is out there , pulsing away

[mic-d]

See http://en.wikipedia.org/wiki/Utility_frequency

Prowl down to "Stability." I was mistaken about more frequent correction. Hey, I said it was just a wild guess, didn't I?

Joe

That's an interesting page, thanks Joe.

Cheers
Michael

[kiwigeo]

The pulses are to remind you to have another beer......

[derekh]

If I remember, I can ask the guys in the Control Centre on Monday. I actually applied for a job there last year but withdrew my application because my manager wanted me to stay with the Retail systems side of the business.

[jaksam]

The noises you are hearing are used by the supply authority to turn off and on controlled tariffs (eg. hot water systems). This is usually done as a requirement of the particular tariff or can be used to reduce load on the electrical network. Not all hot waters are turned off at once (although they can be). Specific hotwaters are controlled by the code in the on-off signals (ie. different "channels"). So even though you may be hearing the signal, it may not be affecting your hot water. There are other loads that can be controlled by the signal, but this will depend on your specific case / tariff / retailer / etc. This signal is picked up by your relay in your meter box and it will either turn off or on as required, thus controlling the load.

WARNING : TECHNICAL INFO FOLLOWS !!!

The technical term is audio frequency load control (AFLC) and is typically 1050 Hz (or it is in the ENERGEX network). It used to be generated by motor generator sets in substations and still is in some locations (they make a lot of noise if you are in the room...) but it is now mostly generated electronically. You will often hear the signal in iron cored appliances (such as the fan) and most often at night when the background noise is low. The signal is also transmitted through the day.

This signal is not used maintain the timing of synchronous motors in clocks. For starters, it's at the wrong frequency (1050HZ instead of 50Hz), the signal is impressed on the 50 Hz signal (FM style) so does not alter the frequency of the carrier (50Hz signal) and the signal is controlled at the substation / feeder level meaning that it is not possible to control all clocks in all areas at once. I have previously been told that the generators will adjust frequency slightly to correct the clocks, but I don't know how often they do it or even if they still do. Adjusting frequency can also cause grief with respect to the stability of the electricity transmission network, so I am guessing very small adjustments only when necessary.

So I think it's either the AFLC signal or aliens...

Jaksam