Ametek SEQUOIA Series - Advanced Measurements; Harmonic Analysis; Output Voltage AC Zero Alignment, AC-Mode

Sequoia / Tahoe Series User Manual California Instruments
248 M447352-01 REV-A
Operating
Voltage Mode
Measurement Value
Measurement System
Signal Coupling
AC RMS of AC component AC
DC Total RMS, AC plus DC components DC
AC+DC Total RMS, AC plus DC components DC
Table 7-2. MEASUREMENTS Parameter Value Derivation
7.1.1 Accuracy Considerations
When using the power source for measurement purposes, always consider the accuracy specifications
when interpreting results. Measurement inaccuracies become more pronounced as the signal being
measured is at the low end of the measurement range. This is particularly relevant for low current
measurements. The Sequoia Series power source develops high levels of output power, and, accordingly,
is optimized for providing and measuring high-load currents. When supplying low power loads,
measurement inaccuracies on RMS and peak current values will also affect other parameters that are
derived from those measurements, such as power, power factor, and crest factor.
The measurement system of the power source uses a data acquisition system with a 47 kHz bandwidth.
This means that high-frequency components of the measured signal are filtered out. Any contribution to
the RMS value of voltage and current components above the filter cutoff frequency would not be reflected
in the measurements. Accordingly, voltage and current measurements of waveforms with significant
harmonic content at high frequencies would incur additional errors.
7.2 Advanced Measurements
The Sequoia/Tahoe Series power source offers advanced power analyzer measurement capabilities
through DSP-based digitization of the output voltage and current waveforms. These functions may be
accessed through the menus of the MEASUREMENTS screen. The full capability of advanced
measurements could be accessed through the remote digital interface using SCPI commands or the
Sequoia Virtual Panels GUI; refer to the Sequoia Series Programming Manual P/N M447353-01, Tahoe
Series Programming Manual P/N M445374-01 or refer to AMETEK PPD website,
www.programmablepower.com, to download the latest version.
7.2.1 Harmonic Analysis
The power source analyzer performs a fast Fourier transform (FFT) on both voltage and current. The
resulting frequency spectrum (DC through 49th harmonic) can be displayed on the LCD display in a tabular
as well as a graphical format.
7.2.2 Acquiring FFT data
To perform an FFT analysis on the output of the power source using the front panel display, proceed as
follows:
1. Navigate to the HARMONICS menu of the MEASUREMENTS screen; refer to Figure 7-1.