the hair drier we tested, have two switch for different heat level. we found when MAX power, the signal from CT sensor is well, but when set to middle level, the signal from CT sensor is bad, fixed DC signal. so let the BL0910 energy meter chip lost some data, let the data incorrect, so in this case, should chose the CT sensor that can anti-DC signal version, just this CT sensor will be larger.
the signal is well, it's a sine wave.
the signal is bad, not sine wave.