Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, Firmware rev. 3.0 or LATER - Manual (Page 170)

170 Publication 1404-UM001F-EN-P - November 2009
Chapter 8 Advanced Features
IEEE-519 TDD and IEEE-519 Pass/Fail
IEEE-519 is the IEEE standard for Recommended Practices and
Requirements for Harmonic Control in Electrical Power Systems. The
1404-M6 refers to the 1992 version of this standard. IEEE-519 provides
recommended limits for the level of harmonic current injection at the
Point of Common Coupling (PCC) between the utility and your setup.
The PCC is typically defined as the location in the power distribution
system where the utility meters are connected. The standard provides
recommended limits for individual harmonic components as well as a
limit for Total Demand Distortion (TDD). Total Demand Distortion is
defined as the root sum square of the current distortion expressed as a
percent of the maximum fundamental demand load current (based on
the maximum demand over the applicable demand interval). The
formula for computing TDD is the same as the IEEE THD formula
except the configured value for maximum fundamental load current is
substituted for the magnitude of the measured fundamental load
current.
Table 10.3 of the IEEE standard specifies the limits. The appropriate
limits are selected by computing the ratio of the available short circuit
current to the maximum fundamental demand load current. The row
of the table that corresponds to the ratio is then used to determine the
proper limits for each of the individual harmonics and the TDD
specified in the table columns. IEEE-519 also recommends maximum
voltage distortion levels that the utility should remain below.
Table 11.1 of the IEEE standard specifies these limits based on the
magnitude of the line to line voltage at the PCC. Once configured, the
1404-M6 will automatically monitor the system voltage and current for
IEEE-519 compliance.
Harmonic Magnitude
The powe rmonitor calculates the RMS magnitude of each individual
harmonic. Results are calculated for harmonics 1…41 (M6) or 1…63
(M8) for all 7 voltage and current channels. Each result is expressed in
RMS volts or amps.
TDD
∞
Σ
n 2 =
Hn ( ) 2
H1
------------------------- =
Where:
•
H
n
= magnitude of the n
th
harmonic
(n
≤
41 or 63)
•
H
1
= maximum fundamental load
current