Allen-Bradley 1404-M4, User Manual

Page: 155 / 356

Publication 1404-UM001D-EN-E - October 2004
Advanced Features 8-5
The total number of data points is 4600 for capture type 0, 1 and 2
and 9200 for capture types 3, 4 and 5.
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 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 Table 39
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:
N
datapoint_oscillogram
N
block
1 –
( )
N
datapoint_this_read
+ =
N
datapoint_oscillogram
= the sequence number of the data point in the oscillogram channel
N
block
= the block number
N
datapoint_this_read
= the data point number (1 to 20 or 1 to 50) in the current read
M
i
M
max rms
( )
2
•
R
max
--------------------------------------
N
t
M
data
• •
=
Allen-Bradley HMIs