Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, Firmware rev. 3.0 or LATER - Manual (Page 30)

30 Publication 1404-UM001F-EN-P - November 2009
Chapter 3 Powermonitor 3000 Unit Operations
Voltage, Current, and Frequency Results
Line-to-line voltage results (L1-L2, L2-L3, and L3-L1) are calculated for
all wiring modes. Line-to-neutral voltage results (L1-N, L2-N, and
L3-N) are calculated in wye and single-phase wiring modes only. In
delta wiring modes, line-to-neutral voltages return a zero value.
Average line-to-line (Avg. L-L) and line-to-neutral (Avg. L-N) voltage
results return the mathematical average of the three line-to-line or
line-to-neutral voltages, respectively. For single-phase wiring modes,
the average line-to-neutral voltage is the mathematical average of
phase 1 to neutral (L1-N) and phase 2 to neutral (L2-N) voltages.
Voltage results return 999 if the line-to-neutral voltage exceeds
347 volts.
Current results include individual phase current (L1, L2, L3) and
average three-phase current. L4 current returns neutral or
zero-sequence current (refer to symmetrical component analysis
discussion below).
Frequency results include Last cycle frequency and Average
Frequency, calculated over your selection of either one or the last
eight cycles. Frequency results return 0 if either the frequency is less
than 40 Hz or if the voltage magnitude on all three voltage inputs is
too low. Frequency results return 999 if the frequency is greater than
75 Hz. The power monitor selects one voltage phase input for
frequency calculations and automatically switches to another in case
of a phase loss. Frequency source indicates which phase is used to
calculate frequency results.
Frequency source is accessible only via communication.
Phase rotation returns a value indicating forward (ABC), reverse
(ACB) or no rotation.
RMS Resolution and Averaging
There are a number of configuration options in the power monitor
that affect metering results.
•
RMS Resolution – the high-resolution setting provides more
accurate RMS results when significant levels of harmonics are
present. You may also configure for nominal resolution if you
require faster update rates but can accept lower accuracy as a
trade-off. The M4 default is Nominal. The M5/M6/M8 default is
High.
•
RMS Result Averaging – the default setting provides a more
steady result by averaging the results of the last eight
calculations. You may also configure no averaging for the fastest
response to a changing signal.