User Manual, Firmware rev. 3.0 or LATER Owner's manual

164 Publication 1404-UM001F-EN-P - November 2009
Chapter 8 Advanced Features
Each data point is expressed in calibrated analog-to-digital (A/D)
converter counts with a resolution of 8192 (13-bit w/sign) or 128 (7-bit
w/sign). A client may calculate the primary-side instantaneous voltage
or current magnitude of each data point by using the following
formula:
Where:
• M
i
= instantaneous value of the voltage or current data point
• M
(max rms)
= max rms magnitude
= 399.0 line-to-neutral volts for channels 1, 3, and 5
= 691.1 line-to-line volts for channels 1, 3, and 5
= 10.6 amperes for channels 2, 4, 6, and 7
• R
max
= maximum resolution
= 8192 for 13-bit w/sign, capture types 0, 1, and 2
= 128 for 7-bit w/sign, capture types 3, 4, and 5
• N
t
= PT or CT ratio
= PT or CT primary / PT or CT secondary
• M
data
= value of the data point from the Oscillograph
Configuration/Read-back Data Select table
For example, consider the following capture:
• PT primary = 13.8 kV
• PT secondary = 120 V
• CT primary = 100 A
• CT secondary = 5 A
• Delta voltage mode (line-to-line)
• Capture type = 2
You would multiply each data point by the following factor to
correctly display the waveform:
M
i
M
max rms()
2•
R
max
--------------------------------------
N
t
M
data
••=
Factor 691.1 1.414•()8192⁄ 13800 120⁄()• 13.72==