User Manual    AMETEK Programmable Power 
RS Series    112 
4.5.2  3Pi Controller Measurements 
For RS Series with the -3Pi controller, the following four measurement screens are available: 
Mode  AC  DC  AC+DC 
MEASUREMENTS 1 
VOLTAGE  AC rms voltage  DC Voltage  AC rms voltage 
POWER  Real power  n/a  n/a 
MEASUREMENTS 2 
VA POWER  Apparent power  power  Apparent power 
PEAK CURR  Highest AC current 
found 
Highest DC current 
found 
Highest AC 
current found 
POWER FACT  Power factor  n/a  Power factor 
CREST FACT  Crest factor  n/a  Crest factor 
MEASUREMENTS 3 
VOLT THD  Voltage distortion  n/a  Voltage distortion 
CURR THD  Current distortion  n/a  Current distortion 
INST PK CURR  Instantaneous peak 
current 
Highest DC current 
found 
Instantaneous 
peak current 
PHASE  Phase angle  n/a  Phase angle 
 
The 3Pi controller has a fourth measurement screen for harmonics and trace analysis 
measurements. This subject is covered in the next chapter. 
Note: The V and I distortion calculations are based on H2 through H50 with the RMS current in 
the denominator. Note that some definitions of THD use the fundamental component (H1) as the 
denominator. This may result in different readings between instruments depending on the 
implementation chosen. 
Measurements are always running in the background. When the user selects a measurement 
screen for display, the AC source first updates all the measurement parameters before 
displaying the requested screen. This process may take up to a second. 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. 
The measurement method for voltage and current will depend on the power source’s operating 
mode.  The following table shows the return value type (rms or average) and method of coupling 
when the measurement command is initiated with a different extension at various operating 
modes (AC, DC or AC + DC).