Tektronix TCP300 Series, User Manual, Page: 32 / 80

Getting Started
AC Measurements
To measure AC current only, and remove the DC component of the current being
measured, follow the instructions below. These are identical to the instructions for
DC current measurements except that the ampli
fi er coupling in step 2 is set to AC.
1. Verify that the oscilloscope input coupling is set to DC.
2. Verify that the ampli fi er input coupling is AC, and the input impedance is set
to 50 Ω . (The NOT TERMINATED INTO 50 Ω LED is on if impedance
is not 50 Ω .)
3. Adjust the ground reference of the oscilloscope to move the trace to the
desired graticule line.
4. Lock the probe closed without a conductor passing through it, and then press
the ampli
fi er PROBE DEGAUSS AUTOBALANCE button.
WARNING. Do not clamp the TCP305 or TCP312 current probes around
uninsulated wires. Damage to the probe or personal injury may result. Only use
the TCP305 or TCP312 current probes on INSULATED wires.
The TCP303 and TCP404XL current probes can be used to measure current on
uninsulated wires. However, the circuit must be de-energized when connecting or
removing the current probe.
5. Open the probe slide, place the probe around the conductor under test, and
then lock the slide. For correct measurement polarity, make sure the probe
arrow is pointing in the direction of conventional (positive to negative)
current
fl ow. Reversing the fl ow will invert the displayed current waveform
on the oscilloscope.
NOTE.
Even when making AC current measurements, leave the oscilloscope
coupling on DC. Change only the ampli fi er coupling to AC. Using the oscilloscope
AC coupling may cause the ampli fi er to exceed its output dynamic range.
6. Adjust the oscilloscope time base and trigger as needed.
14 TCPA300/400 Ampli fi ers and TCP300/400 Series Current Probes User Manual