6-2
IM WT310E-01EN
Auto Range Operation
The auto range operation when harmonic measurement data is displayed is the same as the operation
during normal measurement. For details, see section 2.3.
Note
If the range changes repeatedly in auto range mode, PLL synchronization is lost, and resynchronization is
repeated. Consequently, this instrument is unable to obtain correct measurements, and this may lead to
further instability in the range setting. In such cases, set a fixed range appropriate for the measured values.
Data Update Interval, Holding Measured Values, and Updating
Display Data
Same as normal measurement.
Error Display
When the Fundamental Frequency of the PLL Source Is Outside
the Measurement Range
The fundamental frequency range of the PLL source is 10 Hz to 1200 Hz. If the frequency is not within
this range, all harmonic measurements will be displayed as no data (------).
Note
The measurement range of the harmonic frequency in harmonic measurement is different from the frequency
measurement range of normal measurement. For details, see section 7.3 in the Getting Started Guide, IM
WT310E-02EN.
Over Range Indication
Harmonic measurements do not have over range indication (---oL-) or indication for measured values
that are too small.
* See “Indications When the Measured Value Is Too Small” on page 1-12 in the Getting Started
Guide, IM WT310E-02EN.
Measurement Suspension/No Data Indication (Hyphens)
Hyphens are displayed in the following circumstances.
• When there is no analysis data to display during harmonic measurement data display
• Immediately after the harmonic measurement data display is turned on
• When PLL synchronization is lost and resynchronization is taking place
• Until the first measurement data is acquired after the settings are changed
• When the harmonic order of display A exceeds the upper limit of measured harmonic, which is
determined by the fundamental frequency
Averaging
If the averaging type is set to EP (exponential averaging), averaging is performed using the specified
attenuation constant.
Effects of Aliasing
This instrument does not have anti-aliasing filters. Aliasing errors occur in the following circumstances.
Fundamental Frequency f (Hz)
Aliasing Occurs When
10 ≤ f < 75
512th and higher harmonic components are present
75 ≤ f < 150
256th and higher harmonic components are present
150 ≤ f < 300
128th and higher harmonic components are present
300 ≤ f < 600
64th and higher harmonic components are present
600 ≤ f < 1200
32th and higher harmonic components are present
6.1 Harmonic Measurement Feature