Sequoia / Tahoe Series User Manual California Instruments
M447352-01 REV-A 247
7. Standard Measurements
The Sequoia Series power source is continuously sampling the instantaneous output voltage and current
and storing the data in a buffer that holds 4096 voltage and current data points (frame). The data is used
to calculate the values of the parametric measurements, with two cycles of measurement required to derive
an RMS value. The voltage and current are sampled at two rates, 93.75 ksps or 31.25 ksps, depending on
the output frequency. At ≥ 48 Hz, the sample rate is 93.75 ksps, giving a derivation time of 43.69 ms per
frame. There is hysteresis of 4 Hz when switching to the lower sample rate, so at ≤ 44 Hz, the sample rate
is reduced to 31.25 ksps, and the time required per frame is 131 ms.
Measurement of output parameters is available in either the MEASUREMENTS screen or the
DASHBOARD screen. The MEASUREMENTS screen allows only for the display of measurements, and
provides either a group display of parameters, or a dedicated screen for each parameter that could be
selected when a single parameter is of concern. The DASHBOARD screen provides the display of voltage,
current, and frequency, as well as the ability to set their values. The full extent of the measurements
capability 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 M447354-01 or refer to AMETEK PPD website, www.programmablepower.com,
to download the latest version.
7.1 Parameter Measurements
The output mode of operation, whether AC, DC, or AC+DC, determines which parameters are available in
the MEASUREMENTS screens, as shown in Table 7-1.
Parameter
Output Mode of Operation
AC DC AC+DC
VOLTAGE RMS of AC voltage RMS voltage RMS voltage
CURRENT RMS of AC current RMS current RMS current
FREQUENCY Frequency N/A Frequency
REAL POWER Real power Real power Real power
APPARENT
POWER
Apparent power Apparent power Apparent power
PHASE Phase angle N/A Phase angle
POWER FACTOR Power factor N/A Power factor
CREST FACTOR Crest factor N/A Crest factor
VOLTAGE THD %THD N/A %THD
CURRENT THD %THD N/A %THD
ENERGY Watt-Hour Watt-Hour Watt-Hour
Table 7-1. MEASUREMENTS Screen Parameters
The output voltage mode also determines how parameter value measurements are derived, and how the
measurement signals are internally coupled, whether AC or DC; refer to Table 7-2.
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