Table of Contents
Advertisement
7.1 Harmonic Measurement Function
Functional Limitations by Measurement Modes
Relationship between the Rms Values of Voltage U/Current I and Measurement Modes
Measurement mode
Computing method
Characteristics
Display order setting
of the measurement
function
Display on the screen
Display example of the
voltage measurement
function of element 1
*1 When the number of displayed items is set to All, rms is not displayed. Distinguish between normal measured value and total
value by checking the measurement mode display at the upper left of the screen.
7-2
Wide bandwidth harmonic measurement mode and IEC harmonic measurement mode
perform internal computation differently from other measurement modes in order to
achieve the respective harmonic measurement functions. Therefore, some functions such
as waveform or bar graph display on the screen, store function, motor evaluation function
(option) cannot be used in these measurement modes. In addition, some measurement
functions such as peak measurement, integration, and efficiency computation cannot be
carried out. For a list of functions with limitations and measurement functions that cannot
be measured, see appendices 10 and 11 in the User's Manual IM WT3001E-01EN.
The rms values of voltage U and current I consist of two types: normal measurement
value and total value. The computing method and display of these values vary depending
on the measurement mode as shown below. The normal measured value and total value
cannot be measured simultaneously.
Normal Measured Value
Normal measurement mode
Waveform computation mode
FFT mode
Voltage fluctuation and flicker measurement mode
Cycle-by-cycle measurement mode
Compute the average based on the sampling
data in the measurement period
For details, see appendix 1, in theUser's Manual
IM WT3001E-01EN.
Total value of all frequency components in the
measurement frequency bandwidth
[---]
The "rms" indication is attached to the
measurement function.
*1
Urms1
Example in Which a Difference Occurs between the Normal Measured
Value and Total Value.
For example, let's assume that a 10-kHz harmonic component is included in the inverter
voltage signal with a fundamental frequency of 50 Hz. The total value that is determined
by measuring this signal from 0
rms components exceeding 5 kHz. Therefore, the value does not include the rms
component of 10 kHz. In addition, if the voltage signal includes a 316-Hz (frequency
that is 6.32 times the fundamental frequency) component, it is not included in the total
*2
value.
This is because the total value uses a computing method that takes the total of
the rms components of each order in the specified range. On the other hand, the normal
measured value is an rms value that includes the 10-kHz and 316-Hz components
described above. Moreover, if the measurement bandwidth is limited by a line filter, both
the total value and normal measured value do not include rms components that exceed
the measurement bandwidth.
*2 In IEC harmonic measurement mode, rms components that are not an integer multiple of
the fundamental signal may be included. For details, see chapter 9.
IEC harmonic measurement mode
Wide bandwidth harmonic measurement mode
Total value of the components of each order between
the minimum order and maximum order that are
specified in the setup menu of the measured order of
harmonic measurement.
For details, see section 7.10.
Value that excludes rms components of orders
outside the specified order range and rms
components that are not integer multiples of the
fundamental frequency.
The "rms" indication is not attached to the
measurement function.
th
th
order (DC) to 100
order (5 kHz) does not contain
Total Value
*2
[Total]
U1
IM WT3001E-51EN
Advertisement
Table of Contents
