Tektronix TCP300A, User Manual

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Reference Notes
Extending Current Range
You may encounter situations where your measurement exceeds the maximum
current rating of the connected probe. This section discusses methods for
extending AC and DC current ranges without exceeding speci
fi ed limits.
WARNING. To avoid personal injury or loss of life due to shock or fi re, do
not exceed the speci fi ed electrical limits of the TCPA300 and TCPA400 or any
applicable accessories. When using multiple conductors, do not exceed current
limits on either conductor.
Extending DC Range
If you want to measure a low-amplitude AC component that is superimposed on
an extremely large steady-state DC component (such as in a power supply), or
if you want to extend the DC current range of your probe, you can add offset
(bucking) current with a second conductor.
WARNING.
To avoid injury or loss of life from shock or fi re, do not put more than
one uninsulated conductor at a time in the probe jaws. An uninsulated conductor
is de
fi ned as any conductor without insulation or without insulation rated for the
voltage present on the conductor under test.
To supply additional bucking current, do the following and refer to the illustration.
(See Figure 16.)
1. Place a second conductor that has a pure DC component of known value in
the probe jaw with the conductor under test.
2. Orient the second conductor so that the bucking current fl ows in the opposite
direction of the DC fl ow in the conductor under test.
3. To determine measurement values, add the value of the bucking current to
the displayed measurement.
32 TCPA300/400 Ampli fi ers and TCP300A/400 Series Current Probes User Manual