[time-nuts] Logging the grid frequency....

Peter Gottlieb nerd at verizon.net
Sat Feb 23 14:05:36 EST 2013


Some grid connected inverters have a LOT of noise around the zero crossings, so 
much so that certain digital power meters won't function as they can't get 
frequency lock.  I've seen this on the large Parker units as well as the low bid 
units out of China.  So if you have solar or wind farm alternative energy 
projects nearby you may indeed see excessive noise.

Excess noise and high order harmonics from such inverters has on occasion caused 
capacitive line filters on nearby equipment to overheat and catch fire.

Peter



On 2/23/2013 7:53 AM, Didier Juges wrote:
> "I am curious how this compares with the zero crossing method."
> I suppose it should work much better because this method will not be so sensitive to noise around the zero crossings. It will use the entire waveform.
>
> Didier
>
>
>
> Sent from my Droid Razr 4G LTE wireless tracker.
>
>
>
> -----Original Message-----
> From: Gabs Ricalde <gsricalde at gmail.com>
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Sent: Fri, 22 Feb 2013 9:01 PM
> Subject: Re: [time-nuts] Logging the grid frequency....
>
> Hello,
>
> I also don't have a Picotest or similar equipment but I've done similar
> things by using the line input of a soundcard. Multiply the recorded
> signal with a 60 Hz quadrature oscillator, apply a low pass filter then
> do some analysis on the resulting phasor. The stability of the sound
> card oscillator should be enough for this purpose.
>
> You can measure the frequency difference w.r.t. the 60 Hz oscillator by
> taking the slope of the phasor angle (be careful with phase wraparounds)
> and you can do this as often as you like. I'm curious how this compares
> with the zero crossing method.
>
> On Fri, Feb 22, 2013 at 8:46 PM, Daniel Mendes <dmendesf at gmail.com> wrote:
>> Hi, I have a Picotest U6200A. I´m trying to log the grid frequency (60Hz) to
>> generate data for my work. I need to get data from every cycle. I setup
>> their program (it always starts in chinese... very funny) but seems that it
>> can only log every 100ms. Questions:
>>
>> 1) Is that a limitation of the equipment or the software?
>>
>> 2) Using direct comands, can I get data faster?
>>
>> Thanks for any help...
>>
>> Daniel
>>
>>
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