Appendices
52
The measured phase angle between
corresponding voltage and current channels was
not in the range: 0 <= <= /2
The ordering of the current phases was different
to that of the voltage phases or the angle between
two phases was not 120º
Division by zero was attempted during data
acquisition
An illegal value was detected for one or more of
the following quantities during data acquisition:
Calibration constants, balance values, admittance,
estimated physical parameters
(CHECK MOTOR and LEARN only). The measured
frequency differed from the nominal value. During
the learning period, AMU learns the motor only at
the dominant frequency. In inverter driven
systems, it is important to set the nominal
frequency to this dominant frequency otherwise,
AMU may never complete the learning period.
This condition is relaxed during normal monitoring
(IMPROVE and UPDATE) where unlearned
frequencies are updated automatically
Illegal value for the mean frequency (IMPROVE,
UPDATE and
MONITOR)
The estimated admittance is inconsistent with the
measured RMS values for voltage and current.
This usually indicates excessive noise in the data