2-12
IM 760301-01E
The crest factor can be set to 3 or 6 on the WT3000. The measurable crest factor is as
follows:
{measurement range
×
CF setting (3 or 6)}
Measured value (rms value)
Crest factor (CF) =
* However, the peak value of the input signal must be less than or equal to the maximum
allowable input.
If the crest factor of the measured signal is greater than the specifications of the
measurement instrument (the crest factor defined at the rated input), the signal can be
measured by setting a greater measurement range.
For example, even if CF is set to 3, measurement is possible for signals with a crest
factor greater than 5 when the measured value (rms value) is less than 60% of the
measurement range.
If the minimum effective input (1% of the measurement range) is being applied at CF = 3,
measurement for CF = 300 is possible.
The voltage range, current range, effective input range, and measurement accuracy vary
depending on the crest factor setting. For details, see chapter 12, “Specifications.”
Input Filter «For procedures, see section 4.8.»
There are two types of input filters. The WT3000 makes measurements by synchronizing
to the input signal. Therefore, the frequency of the input signal must be measured
accurately.
• Line Filter
The line filter is inserted into the voltage, current, and power measurement input
circuit and directly affects the voltage, current, and power measurements (see the
block diagram in section 2.1). When the line filter is turned ON, the measured value
does not contain high frequency components. Measurement of voltage, current, and
power is possible by eliminating high frequency components from inverter waveforms,
strain waveforms, etc. The cutoff frequency is selectable.
• Frequency Filter
The frequency filter is inserted into the frequency measurement input circuit and
affects frequency measurements. If the display update rate of the WT3000 is set to 50
ms, 100 ms, 5 s, 10 s, or 20 s, it affects the detection of the measurement period for
voltage, current, and power measurements (see section 4.7 and appendix 6). In
addition, if the data update rate is as indicated above, the frequency filter is also used
to accurately detect the zero crossing (see section 2.2 and appendix 6). The
frequency filter is not inserted into the voltage, current, and power measurement input
circuit. Therefore, the measured values include high frequency components even
when the frequency filter is turned ON.
2.3 Measurement Conditions