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note the blinking upper bar on the
bar graph (inrush rms current), and
the displayed level (running rms
current).
8. To view the maximum inrush
current, press the MIN-MAX
pushbutton once.
9. Repeat step 6, if necessary.
10. To clear RECORD, press the MIN-
MAX pushbutton for 2 seconds.
6.4 Distribution Transformers
You can measure excessive current,
load balance between phases, true-
rms and frequency of neutral current.
True-rms measurement yields the
effective value.
1. Press the ON-OFF pushbutton to
turn on this Meter.
2. Clamp around a phase wire
of the transformer. Be sure the
clamp jaws are securely closed, of
measurements will not be accurate.
3. Observe the display for true-rms
current flow.
4. Repeat your measurement for
each phase to observe balance.
Unbalanced phases cause large
neutral currents flow.
5. Clamp around the neutral wire.
6. Observe the display for true-rms
current flow. Any significant flow,
with balanced phases, indicates the
presence of harmonic currents.
7. Press the Hz pushbutton to
measure the frequency of neutral
wire. Reading indicates the
frequency of the dominant current
flow (in case of harmonic current
flow, 180Hz reading in a 60Hz
system).
8. To freeze the digital display, press
the HOLD pushbutton.
9. To measure peak amperes, press
the SOFT CREST pushbotton twice
(PEAK is displayed).
10. To record readings and to
view maximum, minimum, and
average values, press the MIN-MAX
pushbutton.
11. To clear RECORD, press the MIN-
MAX pushbutton for 2 seconds.
6.5 Adjustable Speed Motor
Controllers
You can measure input current,
output current and frequency of the
adjustable speed motor controllers.
The output current frequency is
used to calculate the rotating speed
of the motor, while input current
frequency is used to measure
the frequency of the power line.
The frequency of the output current
is important because the voltage
frequency is often meaningless for
the calculations of motor controller
speed.
