[time-nuts] Re: measuring the mains frequency

[Alex Pummer]

Hi Andy, there was a website, which showed the nine freq. error around 
the whole world in real time, did you see it ?and if yes where it is
73
KJ6UNH
Alex

On 2/28/2023 12:03 AM, Andy Talbot via time-nuts wrote:
> I use the CCP module in a 16F628 PIC microcontroller.   Measuring the time
> for four cycles of the mains and then calculating its frequency.  My
> version gives a resolution of about 0.002Hz, but by changing the number of
> cycles, clock frequency etc. this can be tweaked for even higher resolution
>
> In the UK the frequency variation is allowed to be an absolute maximum  of
> +/-0.5Hz, beyond which automatic load shedding kicks-in.  This happened on
> 9 August 2019 when two near-simultaneous failures occurred on the National
> Grid.
> https://www.ofgem.gov.uk/sites/default/files/docs/2019/09/eso_technical_report_-_final.pdf
>
>
> Andy
> www.g4jnt.com
>
>
>
> On Tue, 28 Feb 2023 at 05:14, Demetrios Matsakis via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
>> A few years ago I talked with Prof. Liu at Univ of Tennessee.  She and her
>> students had measurements all over the USA. Here is an interesting recent
>> paper of hers: https://par.nsf.gov/servlets/purl/10234030, which has
>> references to still other papers.  Her bio at the end tells a little more
>> about her activities.
>>
>>> On Feb 27, 2023, at 2:23 PM, folkert via time-nuts <
>> time-nuts at lists.febo.com> wrote:
>>> Hi,
>>>
>>> Has anyone experimented with measuring the net frequency? (50Hz in
>>> Europe, 60Hz in the USA)
>>>
>>> Me and a friend are trying to do this as accurate and precise as
>>> possible. His solution can do that with only a 0.0006Hz error, mine
>>> sofar does +/- 2Hz.
>>> Deviations of max. 0.150Hz are allowed (according to
>>> https://www.mainsfrequency.com/ ) so 2Hz is useless.
>>>
>>> I tried the following:
>>>
>>> - use the hardware comparator of an AVR328 (Arduino Nano) together with
>>>   a 10kHz clock-source and then count the number of external clock-ticks
>>>   between 2 falling edges.
>>>
>>> - I used something like
>>>
>> https://www.botnroll.com/en/outros/4301-230vac-voltage-sensor-for-arduino.html
>>>   to make the 230V into a 5V (DC) sine wave and connected that to D6 of
>>>   the Arduino. D7 is connected to a voltage divider to get a 2.5V
>>>   voltage reference (should be the zero-crossing voltage of the 230V
>>>   input).
>>>
>>> - connected a PicDiv from Tom (a PD03) to an OXCO and the other end to
>>>   pin D2 (ext interrupt) of the Arduino.
>>>
>>> +/- 2Hz (that's 80PPk right?) is way too much. So i'm curious if someone
>>> has a suggestion on how to improve this?
>>>
>>>
>>>
>>> Regards,
>>>
>>>
>>> Folkert van Heusden.
>>>
>>> p.s. the source code is at https://vanheusden.com/permshare/50hz.ino
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