Application Note

2 Fluke Corporation Event recording (or logging) with a Fluke 287/289 Digital Multimeter
has been reached, then it beeps
and freezes (holds) a stable
reading on the display for the
user to see. If the input changes
to the point that it is no longer
stable, then becomes stable
again, the meter will beep a
second time and hold a new
reading on the display.
Event recording uses a similar
scheme. When the Fluke 289 is
recording, it is looking for peri-
ods of stability. For each stable
or unstable period the meter
logs a start time, the initial
reading, stop time, the maximum
reading, minimum reading (and
the times of their occurrence)
and average reading during
that period. The event recording
feature is designed to store only
enough information to describe
any changes; i.e., events, to the
input signal.
Event recording data
The Fluke 289 excels at record-
ing transition events, but while
it has TrendCapture graphing
capability, it does not have the
kind of large graphical display
resolution needed to analyze all
of the event data. This is where
FlukeView Forms software takes
over, allowing you to view the
recorded data in table or graph
form on a PC. An example is
shown in the figure below.
Looking at this data, you can
see that the recording session
started at 1:54:41 PM and ended
at 2:23:47 PM with an elapsed
time of about 29 minutes. You
can also see that the signal
being measured was stable near
119 V for most of the logging
session.
However, there was one
unstable event detected by
the meter during a 1.6-second
period beginning at 2:18 PM.
The graph clearly shows the
switching event that happened
at that time. What is interest-
ing about this example is that
the table of data shows only six
“events” needed to be stored
in the meter memory over the
entire 29 minutes of logging
to capture the essence of what
happened.
What this illustration shows is
that, with event recording, only
a very small amount of memory
is needed to store the informa-
tion. To capture the same data
using traditional data logging
would require a one-second
sample rate over the entire 29
minutes which would have
produced 1,740 records of data,
yet that level of detail was not
required to detect the problem.
Recording—by the
numbers
Now that we know how the
Fluke 289 records data, let’s
go through the step-by-step
process for recording a desired
signal over time. In this case,
the test will record the signature
of the current drawn by a large
household refrigerator for more
than one day.
The following steps can be
generalized to any recording
situation.
Step 1
Make sure that the battery
indicator in the upper left hand
corner of the Fluke 289 display
shows at least two of the possi-
ble four bars, indicating enough
charge is left for a 24-hour oper-
ation. For any longer recording
period, or if in doubt, replace the
batteries with fresh new ones.
Step 2
Connect the meter to the
circuit being measured.
In this example, the ac current
was measured by connecting
a current transformer probe to
the mA jacks of the Fluke 289.
That is because the probe output
is 1 mA/A. We then place the
jaws of the probe around the
circuit conductor in the distri-
bution panel that is connected
to the breaker dedicated to the
refrigerator. If the DMM function
switch is in any position except
A/mA or μA, the meter will beep
to indicate that the switch must
be in one of these two posi-
tions to proceed, and the display
information screen will show
the details. In this case, we
want the A/mA function. The
meter will sense the presence
of the lead in the mA jack, and
select the proper circuit for the
recording.
Note: Although not required in this
case, if a signal normally varies a full
point, you might want to estimate a
maximum current or voltage that you
expect to encounter, and set manual
ranging to the higher range. This will
prevent recording multiple events due
to auto-ranging.
Step 3
Press the Save (F2) softkey
and highlight the Record option
using the navigation arrows.
Then, press the Record (F1)
softkey below the display.
At this point, the Recording
information screen appears.
Note that the bottom line of this
display indicates the battery
condition. If the battery is par-
tially discharged, the Battery:
partly empty advisory appears.
See step 1 above.
Figure 1.