AMU Use
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3.3.3.2. Calibration factors
Current sensors and assemblies supplied with AMU should be accompanied by a calibration
document containing the sensor’s calibration factor. The values of each calibration factor
should be entered into the correct setting under the Calibration menu. It is important that
the correct factor be entered for each channel, as AMU will not function correctly if the
calibration factors are incorrect.
For channels connected to current transformers, the calibration factor should be equal to
the nominal ratio of the primary to secondary turns. For example a 100A current
transformer with a 5A output and a single primary turn would require a calibration factor of
20. The same transformer with two primary turns would require a calibration factor of 10. A
6500V voltage transformer with a nominal secondary voltage of 100V would require a
calibration factor of 65.
Any channel connected directly to the motor without
an external sensor (i.e. voltage connections on low
voltage units) requires a calibration factor of 1.
3.3.3.3. Motor settings
Nominal voltage, current and frequency:
The nominal voltage, current and speed (in rpm) of the attached motor must be entered
under the Motor Settings menu. These values can be obtained from the motor
specifications. AMU uses these values to determine whether the motor complies with its
specifications and incorrect values are likely to raise alarms. The nominal line frequency (or
most commonly expected frequency in the case of an inverter) should also be set. Similarly,
the motor connection type must be set to one of Star or Delta.
The value of this dominant frequency must be entered
from the Edit Settings menu. If AMU measures the
frequency to be out of the expected range, it will issue
an alarm in both the CHECK MOTOR and LEARN modes
and the user should adjust the frequency setting
accordingly. Nominal speed must be normalized
according to the set frequency. E.g. if the frequency
and speed values on the motor name plate are 50 Hz
and 1500 rpm and if the motor is working on 30 Hz
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