4-6
IM WT310E-01EN
Frequency Measurement Ranges
• The measurement range varies as shown below depending on the data update interval (see section 2.10).
Data Update Interval
Measurement Range
0.1 s
20 Hz to 100 kHz
0.25 s
10 Hz to 100 kHz
0.5 s
5 Hz to 100 kHz
1 s
2.0 Hz to 100 kHz
2 s
1.0 Hz to 100 kHz
5 s
0.5 Hz to 100 kHz
10 s
0.2 Hz to 100 kHz
20 s
0.1 Hz to 100 kHz
Auto*
0.1 Hz to 100 kHz
* If the data update interval is set to Auto, the lowest measurable frequency is as follows
depending on the timeout setting (see section 2.10).
TImeout
Lower Frequency Limit
1 s
2.0 Hz
5 s
0.5 Hz
10 s
0.2 Hz
20 s
0.1 Hz
• This instrument automatically switches between the following six measurement ranges: 1 Hz, 10
Hz, 100 Hz, 1 kHz, 10 kHz, and 100 kHz.
• The WT332E/WT333E simultaneously measures the voltage frequency and the current frequency
of the element selected in display D.
Input Element (WT332E/WT333E only)
The elements that you can select vary depending on the model. Check the model when selecting elements.
• 1, 2, or 3: Display the measured values of element 1, 2, or 3.
• Σ: For the display when the phase angle is being measured, see section 4.1. When the frequency is
being measured, hyphens (------) are displayed instead of measured values.
Note
Phase Angle
• Even when the input signal is the same, the display may change if you change the measurement mode
(RMS, VOLTAGE MEAN, or DC). For details on measurement modes, see section 2.1.
• When either the voltage or current falls to 0.5% or less (1% or less if the crest factor is set to 6 or 6A) of
the measurement range, the phase angle will be displayed as an error (“Error”).
• A proper distinction between phase lag and lead can only be made when both the voltage and current are sine
waves and the ratios of the voltage and current input to the measurement range are not significantly different.
• When the power factor is greater than 1, the phase angle is displayed as follows.
• When the power factor is between 1.0001 and 2.0000, the phase angle is displayed as 0.0.
• When the power factor is between –1.0001 and –2.0000, the phase angle is displayed as 180.0.
• When the power factor is greater than or equal to 2.0001 or less than or equal to –2.0001, the phase
angle is displayed as “Error.”
Frequency
• The period cannot be detected if the AC amplitude is small. For information on the detectable frequency
levels, see the conditions listed under “Accuracy” under “Frequency Measurement” in chapter 7, “Features,”
in the Getting Started Guide, IM WT310E-02EN.
• This instrument measures the frequency by synchronizing with the cycle of the input signal. We
recommend that you enable the frequency filter when measuring an inverted waveform or a waveform
with a high noise level. However, depending on the signal’s frequency and level, the frequency may be
displayed as “Error.” This is because the filter, which has a cutoff frequency of 500 Hz, may attenuate the
signal to a level at which no input signal is recognized.
• Even when the frequency filter is disabled, the frequency may be displayed as “Error” if the frequency is
greater than the measurement range and the internal circuit attenuates the signal to a level at which no
input signal is recognized.
4.3 Displaying Phase Angles and Frequencies
