[time-nuts] Simple AC mains zero-cross detector

[Bob Camp]

Hi

Using GPS timing for power network analysis and control dates back into the 1980’s. The guys at Quebec Hydro set up the first system I’m aware of. They had tried it with Loran-C before, but the noise in the vicinity of a major power station made that impossible. GPS being microwave helped them a lot with that part of it. They did a paper at FCS(?) on the results. Back then being able to actually get very accurate phase data over a 100’s of mile range  was a pretty novel thing. Using GPS timing for this actually pre-dates the whole CDMA / GPSDO thing. 

Bob

> On Dec 18, 2014, at 5:59 PM, Mike Garvey <r3m1g4 at verizon.net> wrote:
> 
> There is an interesting article in the Nov/Dec issue of Inside GNSS
> describing the robust measurement of "...voltage and current phasors at
> widely dispersed locations in a power grid".  A Phase Measurement Unit
> measures and time stamps the voltage and current phasors "...thousands of
> times per second..." to an accuracy of <1 us using GPS.  The authors discuss
> several strategies for dealing with jamming and spoofing of the civil GPS
> signals.  It's a good read.
> 
> See http://www.insidegnss.com/node/4281 
> 
> Mike 
> 
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Hal Murray
> Sent: Wednesday, December 17, 2014 3:28 AM
> To: Discussion of precise time and frequency measurement
> Cc: hmurray at megapathdsl.net
> Subject: Re: [time-nuts] Simple AC mains zero-cross detector
> 
> 
> csteinmetz at yandex.com said:
>> That one is not ideal for this task, because (i) its output pulse is 
>> symmetrical about the mains zero cross, and (ii) the hysteresis zone  
>> is not well characterized and will drift with temperature and input  
>> voltage.  So, there is no edge that is well characterized in relation  
>> to the AC mains zero cross.
> 
> What are you going to do with data from the line accurate to 1 microsecond?
> 
> 
> 
> --
> These are my opinions.  I hate spam.
> 
> 
> 
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