VLT
®
5000 Series
List of handling of multi-references
■ Automatic Motor Adaptation, AMA
Automatic motor adaptation is a test algorithm that
measures the electrical motor parameters at a motor
standstill. This means that AMA itself does not sup-
ply any torque.
AMA is useful when commissioning systems, where
the user wants to optimise the adjustment of the VLT
frequency converter to the motor applied. This fea-
ture is used in particular where the factory setting
does not adequately cover the motor in question.
There are two motor parameters that are of primary
significance in automatic motor adaptation: the sta-
tor resistance, Rs, and the reactance at normal
magnetising level, Xs. Parameter 107 allows a
choice of automatic motor adaptation, with determi-
nation of both Rs and Xs, or reduced automatic
motor adaptation with determination of only Rs.
The duration of a total automatic motor adaptation
varies from a few minutes on small motors to more
than 10 minutes on large motors.
Limitations and preconditions:
• For AMA to be able to determine the motor pa-
rameters optimally, the correct nameplate data for
the motor connected to the VLT frequency con-
verter must be entered in parameters 102 to 106.
• For the best adjustment of the VLT frequency
converter, it is recommended to carry out AMA
on a cold motor. Repeated AMA runs may lead
to a heating of the motor that will result in an in-
crease of the stator resistance, Rs.
• AMA can only be carried out if the rated motor
current is minimum 35% of the rated output cur-
rent of the VLT frequency converter. AMA can be
carried out up to one oversize motor.
• If a LC filter is inserted between the VLT fre-
quency converter and the motor, it will only be
possible to carry out a reduced test. If an overall
setting is required, remove the LC filter while run-
ning a total AMA. After completion of the AMA
reinsert the LC filter.
• If motors are coupled in parallel only use reduced
AMA if any.
• When using synchronous motors it is only possi-
ble to make a reduced AMA.
• Long motor cables can have an effect on the
implementation of the AMA function if their resis-
tance is bigger than the stator resistance of the
motor.
MG.51.A1.02 - VLT is a registered Danfoss trade mark
90
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