14
III.2.5. Total Harmonic Distortion (% THD-F)
a. Set the rotary switch at position V. Then select the correct fundamental
frequency by moving the sliding switch at the side of the tester.
b. Insert the test leads into the input jack. Connect the test prods of the test
leads in PARALLEL to the circuit to be measured.
c. Press the FUNC button three times. The symbols of “THD” and “%” will be
shown in LCD. The total harmonic distortion in percentage with respect to
the fundamental frequency (50 or 60 Hz) will be measured and displayed.
%THD-F = (
√
(V2
2
+ V3
2
+ … +V49
2
+ V50
2
) / V1) * 100
Where,
V1: magnitude at the fundamental frequency
V2: magnitude at the second harmonics
…
V50: magnitude at the 50-th harmonics.
NOTE: In the measurement of THD, the response to the button or switch
operation becomes slow due to heavy math calculation.
NOTE: For model 23, users can not disable the auto-power-off function
by holding the FUNC button for 2 seconds in the measurement of THD.
To Next Page
Loading...
