Amprobe ACDC-620T Clamp-On-Multimeter Manuel d'utilisateur télécharger pdf (Page 32)

DISTRIBUTION TRANSFORMER MEASUREMENT

You can measure current, phase imbalance between phases, and true RMS neutral

current. True RMS measurement yields the effective value.

1) Set the rotary switch to " A ".

2) Clamp around a phase wire of the transformer. Be sure the jaws are completely

closed or measurement will not be accurate.

3) Observe the display for true RMS current.

4) Repeat your measurement for each phase to determine balance. Imbalanced

phases and/or harmonics can cause neutral currents.

5) Observe the display for true RMS current reading. If the phases are balance, any

significant current flow on the neutral may indicate the presence of harmonic cur

rents.

6) Press the HOLD/MAX● MINbutton to freeze the digital display.

7) Press and hold the SHIFTbutton (>I sec) to enter the PEAK mode (DH MAX dis

played). Measure the half cycle PEAK current. Divide first reading into the sec

ond reading to determine crest factor. Acrest factor other than 1.4 is an indication

of harmonic current.

8) Press and hold the SHIFT button (>11 sec) to exit the PEAK mode.

9) Press and hold the HOLD/MAX● MIN (> 1 sec) to enter dynamic recording

mode. Momentarily press HOLD/MAX● MIN button to review recorded maxi

mum, minimum, and average values.

10) Press and hold the HOLD/MAX● MIN button (> 1 sec) to exit recording.

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Amprobe ACDC-620T Clamp-On-Multimeter Manuel d'utilisateur Page 32