HOW TO CHECK THIS IN A TRANSMISSION LINE

Nov 29, 2012 at 10:14 PM

HI BUDDY I HAVE DOWNLOADED UR PHASOR UNITS PCB AND SOURCE CODE.......IF I COMPLETE HOW CAN I CHECK THE PMU FOR THE CORRECT OPERATION....PLEASE REPLY.....

Coordinator
Jan 23, 2013 at 9:12 PM

Hi, Sorry for the late reply.  Not many visitors to this discussion area.

Checking a PMU is a challenge if you do not have other PMUs to compare with.  For immediate observations, use an oscilloscope and set the Trigger to the PPS signal from the GPS.  If you are not using a GPS, then use a signal generator that can generate a pulse in fractions of a second evenly divisible by 1, 2, 3, 4, 5, 6, 10, 15, 20, 30, or 60 pulses per second (i.e. 1 second, 1/2 second, etc.).  If you are in 50Hz grid, the fractions will be 1, 2, 5, 10, 25, or 50 pulses per second.  In a second scope channel, measure the sine wave output from the line or from an AC transformer.   You should be able to observe the phase change by the sine wave being either stationary at the pulse if the power source is nominal frequency.  If the power frequency is less than or more than nominal frequency, the sine wave will drift to the left or right of your pulse on the scope.  If you observe the PMU output using PMU connection Tester, you can observe the frequency and phase meaasurement.  If the phase angle is "level" (unchanging) when the signal on your scope is stationary with respect to the trigger, then you know that the PMU frequency and timing matches that of your scope.

Of course, the above a visual method.  For higher precision consider making recordings of the PMU data and the scope measurements (if you have a storage scope) and comparing the actual measurements.  There are some calibration values in the GridTrak PMU for adjusting its timers.

Let me know if you would like additional information regarding this topic.

//aj