AEMC K100 User Manual page 21

• Always zero the Model K100/K110 prior to making a measurement.
See § 4.1 for procedure.
• Make sure that probe jaw mating surfaces are free of dust and
contamination. Contaminants cause air gaps between sensor halves,
making the Model K100/K110 susceptible to external magnetic fields
which can contribute to measurement errors. See §5.3 for cleaning
procedure.
• Do not allow probe jaws to abruptly snap closed from the open state.
This can lead to residual readings. If this happens, the Model K100/
K110 will need to be rezeroed.
• Beware of short-circuit currents. Large in-rush currents (which can
occur when power is first applied in a circuit) and large high-current
transients may cause varying degrees of residual readings. If in doubt
of a particular reading, remove the probe from the conductor under
test and check to see that the display device returns zero. If not, it will
be necessary to rezero the Model K100/K110.
• When using the Model K100/K110 to measure AC currents, keep in
mind the maximum current ratings and the frequency response curves
shown in the electrical specifications section. Dynamic currents that
contain large step discontinuities and/or frequency constituents near
or beyond the measurement passband are subject to measurements
errors and waveform distortion (oscilloscope display). If the red LED
comes on during measurement, the MicroProbe's output signal may be
in error.
Many DVMs provide null (relative) measurement capability. A DVM placed
in the null mode displays the difference between a stored null value and
the input signal.
• You can use a DVM's null function in place of the external DC zero
control to cancel any DC offset from the K100/K110. The DVM null
function should be enabled with the probe removed from the conductor
immediately before measurement.
• You can use a DVM's null function to display changes in measured
current from a fixed (constant) level. In this application, the DVM null
function is enabled with the probe connected to the conductor.
When making null (relative) measurements, the probe aperture current
(not displayed current) must not exceed the maximum ratings set forth in
the specifications section.
DC/AC MicroProbe Models K100 and K110
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