Extech Instruments MN62 User Manual page 9

AC VOLTAGE MEASUREMENTS with VFC, Hz, and % Duty Cycle
WARNING: Risk of Electrocution. The probe tips may not be long enough to contact the live parts inside
some 240V outlets for appliances because the contacts are recessed deep in the outlets. As a result, the
reading may show 0 volts when the outlet actually has voltage on it. Make sure the probe tips are touching
the metal contacts inside the outlet before assuming that no voltage is present.
CAUTION: Do not measure AC voltages if a motor on the circuit is being switched ON or OFF. Large voltage
surges may occur that can damage the meter.
1. Set the function switch to the VFC position.
2. Insert the black test lead banana plug into the negative COM jack.
Insert red test lead banana plug into the positive V jack.
3. Press and hold the VFC button until the meter beeps and VFC is
briefly displayed. The meter is now applying a low pass filter (Note:
VFC is Variable Frequency Control). Press and hold the VFC button
again to exit the VFC mode (END will briefly display).
4. Touch the black test probe tip to the neutral side of the circuit.
Touch the red test probe tip to the "hot" side of the circuit.
5. Read the voltage in the display.
6. Press the Hz/% button to indicate Hz.
7. Read the frequency in the display.
8. Press the Hz/% button again to indicate %.
9. Read the % duty cycle in the display.
% Duty Cycle Note: Duty Cycle measurements are AC only for this meter. Measurement
signals must be 'zero crossing' and must reach ‐0.7V for the meter to properly display Duty
Cycle %.
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