GW Instek APS-1102A - Page 84

APS-1102A User Manual
APS-1102A
4-12
b) Calculation method of the measurement values
Output voltage and current are sampled and A/D converted at 50 kS/s in general or at 5 kS/s when
a sequence program is running. The frequency bandwidth of each analog circuit from a voltage or
current point to the A/D converter is 50 kHz.
RMS, average and peak values of voltage or current and active power values are calculated with
following formulas and sampled values over integer multiples of their periods nearest to 100 ms.
The following values are used as the periods: frequency setting values in INT/ADD modes,
synchronization frequency measurements in SYNC modes, and fixed values to 100 ms in EXT
modes or when the frequency is lower than 10 Hz in any mode.
RMS voltage:
   




1
0
2
1
N
n
rms
nV
N
V
RMS current:
   




1
0
2
1
N
n
rms
nI
N
I
DC average voltage:
 




1
0
arg
1
N
n
nV
N
V
DC average current:
 




1
0
arg
1
N
n
nI
N
I
Max voltage:
   
nVMAXV
peak


Min voltage:
   
nVMINV
peak


Max current:
   
nIMAXI
peak


Min current：
   
nIMINI
peak


Active power:
     




1
0
1
N
n
nInV
N
W
However,
 
nV
,
 
nI
: sample output voltage/current measurement data
N
: Number of samples.
Apparent power, reactive power, crest factor and peak current hold are calculated from equations
below using previous calculated values.
Apparent power:
rmsrms
IVVA 
Reactive power:
 
2
2
var WVA 
Power factor:
VA
W
PF 
Crest factor:
 
rms
peakpeak
I
IIMAX
CF


,
Current peak hold:
 


peakpeakph
IIMAXholdI ,