Allen-Bradley 1404-M4, User Manual

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Publication 1404-UM001D-EN-E - October 2004
8-12 Advanced Features
models and 10 floating-point elements in the M6 and M8 models. The
table contains the following parameters.
•
Channel number: the voltage or current channel being returned.
See above
•
% IEEE THD: Total harmonic distortion in per cent based on the
IEEE definition. Range 0.0 to 1000.0
•
% IEC THD (DIN): Total harmonic distortion in per cent based
on the IEC definition. Range 0.0 to 1000.0
•
Crest factor: Range 0 to 10
•
THD & Crest iteration: each new calculation increments by one
from 0 to 32,767 and rolls back to 0
•
TIF: Telephone influence factor. Range 0.0 to 999.9*10
22
•
K-factor:
Range 0.0 to 999.9*10
22
•
IEEE-519 TDD: Total demand distortion. Range 0.0 to 999.9*10
22
•
IEEE-519 Pass/fail: -1 = unknown, 0 = fail, 1 = pass
•
FFT iteration: each new FFT calculation (used in the previous
four parameters) increments by one from 0 to 32,767 and rolls
back to 0
A data client may determine the relative freshness of data by
comparing the
THD & crest iteration or FFT iteration parameters in
repeated reads of this table.
Reading Individual Harmonic Values
The M6 and M8 models provide several data tables containing
individual harmonic results. Individual harmonic value data is not
available via Modbus communications. Write to Table A.33 to select
the read-back mode, data type (magnitude or distortion per cent)
and/or channel number of harmonic data. A data client reads the
tables listed below in indexed read-back mode to obtain individual
harmonic data. In auto-increment mode, read Table A.34 to index the
channel.
•
Table A.35 Harmonic Results; Odd Harmonics 1 to 21 (M6 and
M8)
TIP
The remaining elements are reserved in the M4 and
M5 models and return values of 0.