Grid Time Errors

This is the Arduino based "Grid Tracker"

Software in the Arduino measures the phase of the power grid AC voltage, in reference to the 1PPS timing signal from a GPS reciever. 

An Ethernet Shield is used to push phase measurements up to the server every 30 seconds.

Grid Tracker Pix

View Live Updates from my Grid Tracker Circuit Here


Ideally, every 24 hrs., a 60 hz power grid should produce exactly 5,184,000 cycles of power.  In reality, load balancing tries to deliver that many cycles. 

MyGridTracker keeps track of the actual number of cycles delivered by comparing the power grid to a precise time standard.  The net difference between the actual number of cycles and the expected number of cycles is referred to as a "time error" and will actually affect electric clocks that are driven with synchronous AC motors.  In the present "digital age", clocks are not affected by the number of cycles of power delivered each 24 hr. period.  

Here are the last 30 days of recorded Grid Tracker activity showing how the grid gets ahead or behind in cycles of power produced.  In general, the grid gets behind when load is increasing (AM), and then catches back up when load is decreasing (PM).



Grid Tracker Detected Anomaly:

Grid Graph

Around 11:09AM local time, there was some sort of event on the grid. The nominal 60Hz power dropped down about 80 mHz.  The system quickly recovered to 50mHz.  A generator may have gone off line or perhaps there was a sudden increase in load.


Large Time Error Correction of over 570 cycles, a time error of almost 10 seconds.


large time correction Feb 2014

Various Grid Time Error Links

WECC  Bonneville at Hanford Bus:  Hanford Frequency


- - - Real Time Status - - -


Real Time New Zeland Power Grid


Eastern Time Error


Dynamic Demand 50Hz Monitor


Synchrophasor Development System





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