Application Note

ManualsBrandsFluke ManualsMeasuring instruments289

Measuring ac and dc voltage

and current—you’ve got that. But

what about the other features

your DMM has—do you ever

use them? Min/Max/Avg is an

especially useful, but often over

looked function of your tool.

occurred, based on the start of

the monitoring process. The

actual start time for the Min Max

session is also displayed so it

is relatively easy to determine

exactly when the signal changes

have occurred.

Knowing the precise timing of

the highest and lowest signal

variations tells you exactly when

unusual events may have taken

place and gives you critical

insight to the stability of the

signal or the system being evalu-

ated. This can be a real asset and

a time saver as a troubleshooting

tool, if you’re looking for intermit-

tent or unusual system perfor-

mances that happen when you’re

not there.

Application Note

From the Fluke Digital Library @ www.fluke.com/library

Under-utilized functions

on your DMM

Min/Max/AVG

Many of the higher performance

digital multimeters contain a

min-max recording function

which allows the user to capture

a wide range of signal anoma-

lies, such as multiple cycle sags

or swells, unexpected signal

ﬂuctuations, or other types of

unattended monitoring of a signal

over time. The function works

by sampling the input signal

approximately every 100 ms or

longer and can be applied to all

primary meter functions (volts,

amps, etc).

With Min/Max/Avg turned

on, the meter will capture, and

temporarily hold, the highest and

lowest signal levels measured by

the meter. In addition, the meter

will maintain a running average

of the signal levels measured

during the monitoring process.

The average reading is useful

for smoothing out noisy signals,

estimating the percent of time a

circuit is active, and determining

the overall level of instability for

the monitored signal.

Timestamp

Along with these captured levels,

some dmm’s such as the Fluke-

287 and 289, have an elapsed

time clock, which timestamps

the highest, lowest and average

values. The timestamp tells you

exactly when these readings

Summary of content (2 pages)

PAGE 1
Under-utilized functions on your DMM Application Note Measuring ac and dc voltage and current—you’ve got that. But what about the other features your DMM has—do you ever use them? Min/Max/Avg is an especially useful, but often over looked function of your tool.
PAGE 2
Recommended procedure for use First and foremost, read the instruction manual and follow all safety precautions and use safe work practices. Using MIN-MAX-AVG function for signal monitoring 1. Select the appropriate meter function for the measurement to be monitored 2. Attach the test probes to the test points using suitable alligator clips or other connection devices that will allow for a solid connection while the monitoring process is in progress. 3.