24
IM 701450-61E
Maximum Record Length That Can Be Computed
The maximum record lengths that can be computed on Math1 and Math2 are as follows:
When the operator is Power and the computation source waveform is CH5 or CH6
2 MW.
When the operator is Z or I
2
t
2 MW.
When the operator is PS
1 kW or 10 kW.
When the operator is Harmonics
When 16 cycles of the 50-Hz or 60-Hz waveform (fundamental waveform) contains waveform data
of 8192 words or more, 16 cycles of waveform data is used. The T/div and record length settings
that meet this condition are listed in the table in appendix 2. For the setup procedure of T/div and
record length, see sections 5.12 and 7.2, respectively, in the
DL7440/DL7480 User’s Manual
.
For all other cases
•
On 4 MW memory models (701450 and 701470), the maximum record length is 4 MW.
•
On 16 MW memory models (701460 and 701480), the record length is 8 MW and 4 MW when
interleave mode is ON and when interleave mode is OFF, respectively.
Computation Start Point
For waveform computation on which the computation start points is specified, the
following range and resolution can be used.
Selectable range
±
5 div
Resolution
10 div
÷
display record length
For a description of the display record length, see appendix 1 in the DL7440/DL7480 User’s Manual.
Time Window
You can select the time window for operator PS. For details, see section 9.6 in the
DL7440/DL7480 User’s Manual
.
Computed Waveform of Harmonics
1
Special measurement/computation conditions and parameter settings shown in the table
below are required for waveform computation of harmonics.
Trigger mode
To perform waveform computation of harmonics continuously when waveform acquisition is
started, set the trigger mode to Normal. For a description of the trigger mode, see section 6.1 in
the
DL7440/DL7480 User’s Manual
.
Time window
Rect (Rectangular).
Number of waveforms and number of waveform data points
To perform computation according to the harmonic current emissions standard, 16 cycles of the
fundamental waveform
2
are required In addition, harmonic computation is performed only when
the number of data points contained in the 16 cycles of waveform data is at least 8192 points.
The T/div and record length settings that meet this condition are listed in the table in appendix 2.
Harmonic order
3
Harmonic components
4
of up to 40th order are computed.
1 Harmonics
Harmonics
refer to sine waves whose frequency is integer multiple of the fundamental wave
(normally sine waves of commercial frequency 50-Hz or 60-Hz). The lowest harmonic
frequency is twice the fundamental frequency. The input current that flows through the power
rectification circuit, phase control circuit, and other circuits used in various electric and
electronic equipment generate harmonic current or voltage on the power line. When the
fundamental and harmonic waves are combined, distortion occurs in the waveform, and
interference sometimes occur in equipment connected to the power line.
2 Fundamental wave and fundamental component
The sine wave with the longest period among the different sine waves derived from the
periodic complex wave. Or the sine wave that has the fundamental frequency within the
components of the complex wave.
Fundamental frequency
refers to the frequency
corresponding to the longest period in the period complex wave.
3 Harmonic order
Integer ratio of the harmonic frequency with respect to the fundamental frequency.
4 Harmonic component
Waveform component with frequency that is an integer multiple (twice or greater) of the
fundamental frequency.
7 Performing Waveform Computation on Power Analysis Parameters
