User Manual
2253i / 2253iX
AMETEK
California Instruments
84
4.5 Measurements
Standard measurements are always available through the
MEAS
key on the front panel. These
measurements are spread across multiple screens to enhance readability. Switching between these
screens can be done by successively pressing the
MEAS
button on the front panel. This will cause the
screen to cycle through all available measurement screens.
4.5.1 Basic Measurements
The following three measurement screens are available:
Parameter
MEASUREMENTS 1
VOLTAGE
AC rms voltage
CURRENT
AC rms current
FREQUENCY
Frequency
POWER
Real power
MEASUREMENTS 2
VA POWER
Apparent power
VAR POWER
Peak current
POWER FACT
Power factor
CREST FACT
Crest factor
MEASUREMENTS 3
VOLT THD
Voltage distortion
CURR THD
Current distortion
PEAK CURR
Instantaneous current found
PHASE
Phase angle (relative to phase A)
Note: The V and I distortion calculations are based on H2 through H50 with the fundamental
component (H1) in the denominator. A RMS referenced calculation may be selected by sending the
“MEAS:THD:MODE FUND” command over the USB or GPIB interface. See i/iX Series Compact
programming manual (CI P/N 6005-961) for details.
Measurements are always running in the background. When the user selects a measurement screen
for display, the power source first updates all the measurement parameters before displaying the
requested screen. Consequently, pressing the
MEAS
key may not always bring up the selected screen
immediately. There will be a perceptible delay. This will prevent the screen from appearing with invalid
or blank readouts.
Note that in AC mode, all measurements are AC coupled only so any DC offset will not be reported.
4.5.2 Accuracy Considerations
Any measurement system has a finite accuracy specification. Measurement specifications are listed in
Section 2. When using the AC source for measurement purposes, always consider these
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 iX Series is optimized for providing and measuring load currents up to 15
Arms. When powering very low power loads, measurement inaccuracies on rms and peak current
measurements will greatly affect derived measurements such as power, power factor and crest factor.
The measurement system on the i/iX Series uses a digital data acquisition system with a 96 KS/s
sampling rate and 48 KHz bandwidth. This means that higher frequency components of the measured
signal are filtered out. Any contribution to the rms value of voltage and current above this cutoff
