Loading ...
Loading ...
Loading ...
True-rms Digital Multimeters
Making Measurements
43
selector to the menu item labeled Hz,%,ms. Next press the
softkey labeled Hz.
Menu
60.050
Hz
VAC123.45
Save Setup
Auto Range
500 VAC0 100 200 300 400
8:10pm
06/13/07
est22.eps
Figure 24. Frequency Display
As shown in Figure 24, the frequency of the input signal is
displayed in the primary display. The volts or amps value of the
signal is shown in the secondary display. The bar graph does not
indicate frequency but indicates the volts or amps value of the
input signal.
Selection between a rising trigger c or falling trigger dedge is
performed by pressing the softkey labeled c d. This softkey
toggles the trigger setting between the two selections.
The following are tips for frequency measurements:
If a reading shows as 0 Hz or is unstable, the input signal may be
below or near the trigger level. You can usually correct these
problems by manually selecting a lower input range, which
increases the sensitivity of the meter.
If a reading seems to be a multiple of what you expect, the input
signal may be distorted. Distortion can cause multiple triggerings
of the frequency counter. Selecting a higher voltage range might
solve this problem by decreasing the sensitivity of the meter. In
general, the lowest frequency displayed is the correct one.
Measuring Duty cycle
Duty cycle (or duty factor) is the percentage of time a signal is
above or below a trigger level during one cycle, as shown in
Figure 25.
The duty-cycle mode is optimized for measuring the on or off
time of logic and switching signals. Systems such as electronic
fuel injection systems and switching power supplies are
controlled by pulses of varying width, which can be checked by
measuring duty cycle.
1.888.610.7664 sales@GlobalTestSupply.com
Fluke-Direct.com
Loading ...
Loading ...
Loading ...