User manual

2 Making Measurements 
Measuring Frequency
50 U1190A Series User’s Guide
Measuring Frequency
This measurement function is applicable for U1192A,
U1193A, and U1194A models only.
Your clamp meter allows simultaneous monitoring of real-
time voltage or current with frequency measurements.
WARNING
Never measure the frequency where the voltage or current level
exceeds the specified range.
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 the figure below.
• The clamp meter 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%
U119XA UG.book Page 50 Thursday, September 15, 2011 4:03 PM