GW Instek GCP-300 Instruction Manual page 9

5. Adjust the probe channel and oscilloscope's time base as necessary to
get a clear and stable view of the signal. Set the oscilloscope input to DC
volts to see both the AC and DC currents; set the channel to AC to see
the AC current only.
The current drawn by different devices look much different than that of
others. While the RMS current can only be used in low frequency current,
the momentary peaks may be quite high. Figure 3 shows the difference
between the line current drawn by a resistive load and a motor controller.
Congratulations on your purchase of the GCP-300, a multifunctional
current probe. When connecting to a digital meter, use the BNC-to-
banana adapter. Connect the black lead to the meter COM (black letters
on the meter), and the red lead to the VΩ input (red letters on the meter).
To measure only AC current, set the meter to measure AC volts.
To measure DC current, set the meter to measure DC volts. Note the
current convention arrow on the probe to get the proper polarity reading.
To increase the measurement sensitivity of the GCP-300 current probe,
loop additional turns of the wire under test through the jaws. See Figure
4. The sensitivity of the GCP-300 current probe is multiplied times the
number of loops in the jaws. For example: 10 mV/A X 4 turns = 40 mV/A.
Figure 3. Typical current waveforms
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