I’m new to the community and I’m in the process of calibrating CT sensors (SCT006) with my emonTx running the continuous monitoring firmware. I searched through previous posts and I wasn’t able to find anyone else with the phase cal problem I’m experiencing and that lead me to believe that I’m doing something wrong. So I’m posting here to seek out some help.
I am operating in the US in case it matters and the hardware has been configured accordingly. I’m able to calibrate the amplitudes accurately against a Keysight DVM and clamp on current meters. The phase calibration, however, is problematic because I can’t seem to fine tune the phase cal term to achieve power factor = 1. In my situation, the greatest pf I can achieve is about 0.85 tuning in 1 deg steps of the phase cal parameter. The calibration procedure (https://learn.openenergymonitor.org/electricity-monitoring/ctac/calibration) indicates this parameter should be in the range 0 to 2. But in my case, monitoring power consumption of my 1500W electric hot water kettle, the pf on power up is about 0.77 which would indicate a phase offset of acosd(0.77) ~40 degs; far outside the specified range. Tuning the phase cal parameter to 40 degs yields the optimal pf of 0.85 and thats the best I can do.
On the subject of the large phase cal correction, I considered MAYBE my water kettle has a reactive impedance component that I’m overlooking so I also checked with a counter top electric oven and observed a similar phase behavior - I just can’t achieve pf=1.
Can anyone offer some insight as to what may be happening here?