Current Measurements Using The Clamp - Extech Instruments EX650 User Manual

Current Measurements Using the Clamp
WARNING: Do not measure the current on a circuit when the voltage increases to more
than 750V AC or 1000V DC. This can cause damage to the instrument and can cause injury to
persons.
1. Ensure that the probe leads are disconnected from the meter.
2. Set the function switch to the
EX650.
3. Use the M button to select AC or DC. For DC (EX655), press ZERO to remove any residual
magnetism and to null the display before clamping onto a conductor.
4. Press the trigger to open the clamp jaws. Fully enclose only one conductor in the jaws
(Refer to Fig. 4‐3). For optimum results, center the conductor in the jaws.
5. Read the current measurement in the display represented by numerical digits (and the 60‐
segment bar graph on the EX655). The display will indicate the proper decimal point and
value. In DC (EX655), when the polarity is reversed, the display will show (‐) minus before
the value.
6. Press and hold the M button to engage the LPF (Low Pass Filter) circuit (to measure
inverters, VFD, etc.). Refer to the dedicated section on Low Pass Filtering.
7. Press and hold the INRUSH button to activate the Inrush Current utility (EX655 only).
Refer to the dedicated Inrush Current section in this User Guide.
Fig. 4‐3 Correct and Incorrect Clamping
for the EX655 or to the 6, 60, or 600
16
positions on the
EX65x‐en‐GB_V1.6 7/16