Brymen BM157 User Manual page 10

9
1. PF (Total Power Factor) is displayed automatically in the secondary mini display.
2. Annunciator "A-lags-V" turns on to indicate an inductive circuit is being measured.
That is, the Current waveform is lagging the Voltage waveform, and the phase-shift
angle θ is "+".
3. On the contrary, together with significant PF values, WITHOUT "A-lags-V" being
turned on indicates that a capacitive circuit is being measured. That is, the Current
waveform is leading the Voltage waveform, and the phase-shift angle θ is "-".
Note:
1. Under proper measurement setups for load circuits, the W (real power) readings are
always positive. Negative W readings indicate reversed clamp-on jaws direction or test
leads polarities, or even incorrect voltage lines are being measured as in 3-phase
measurement setups. Correct them for proper "A-lags-V" indications.
2. When encountering largely distorted waveforms, "A-lags-V" detection might be
affected due to the influence of harmonics. It is recommended to manage (e.g. filter out)
harmonics problems before measuring/dealing with phase-shift problems.