User`s guide

2 Making Measurements
Measuring Frequency
82 U1273A/U1273AX User’s Guide
Figure 2-37 Frequency, pulse width, and duty cycle measurements
Pressing controls the input range of the primary
function (voltage or ampere) and not the frequency range.
1 To measure frequency, rotate the switch to one of the
primary functions allowing frequency measurements
highlighted in Table 2- 20.
2 Press . Probe the test points, and read the display.
NOTE
• Measuring the frequency of a signal helps detect the presence of
harmonic currents in neutral conductors and determines whether these
neutral currents are the result of unbalanced phases or non-linear
loads.
• Frequency is the number of cycles a signal completes each second.
Frequency is defined as 1/Period. Period is defined as the time
between the middle threshold crossings of two consecutive,
like-polarity edges, as shown in Figure 2-37.
• The multimeter measures the frequency of a voltage or current signal
by counting the number of times the signal crosses a threshold level
within a specified period of time.
Rise Time Fall Time
+ Width – Width
Period
90%
50%
10%
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NOTE
To obtain the best measuring results for frequency measurements, please
use the AC measuring path.
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