Phase angle measurement using zero crossing

[leezy90]

I am using  zero crossing to measure the phase angle between (voltage and current) which is represented as  two input in my vi  to  eventually get the power factor. But however the reading i got for the power factor remain at 1 all through no changes. I am using an SCT- 013 -000 current transformer for the current and a power transformer for the voltage 240 - 6V . below is my vi . Can anyone help me troubleshoot why my result is showing 1 for different loads  including resistive , capacitive and inductive loads . 

[johnsold]

Are you working with Nigel91 who posted a similar question in the Electrical Power Suite board?

You have the same problem that he has. For dt = 0.02 (equivalent to a 50 Hz sampling rate) you cannot measure anything about a signal with a frequency higher than 25 Hz. And you could not get meaningful phase information at frequencies above a few hertz.

To get good phase information at typical power line frequencies sampling rates of 1000-1200 Hz or higher should be used.

Lynn