Powerdrive F300 Getting Started Guide 89
Issue Number: 5
Safety
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8.1.2 RFC-A Sensorless mode
Induction motor without position feedback
Pr 00.046 {05.007} Motor Rated Current Defines the maximum motor continuous current
The motor rated current parameter must be set to the maximum continuous current of the motor. The motor rated
current is used in the following:
• Motor thermal overload protection (see section 8.2
Motor thermal protection on page 96, for more
information)
• Vector control algorithm
Pr 00.044 {05.009} Rated Voltage
Defines the voltage applied to the motor at rated
frequency
Pr 00.047 {05.006} Rated Frequency
Defines the frequency at which rated voltage is
applied
The motor rated voltage Pr 00.044 and the motor rated frequency Pr 00.047 are used to define the relationship
between the voltage and frequency applied to the motor, as shown.
The motor rated voltage is used by the field controller to limit the voltage applied to the motor. Normally this is set
to the nameplate value. To allow current control to be maintained, it is necessary for the drive to leave some
'headroom' between the motor terminal voltage and the maximum available drive output voltage. For good
transient performance at high speed, the motor rated voltage should be set below 95 % of the minimum supply
voltage to the drive.
The motor rated voltage and motor rated frequency are also used during the rotating autotune test (see Autotune
Pr 00.040 later in this table) and in the calculations required for automatic optimization of the motor rated speed
(see Motor rated speed optimization Pr 05.016, later in this table). Therefore, it is important that the correct value
for motor rated voltage is used.
Pr 00.045 {05.008} Rated Speed Defines the full load rated speed of the motor
Pr 00.042 {05.011} Number Of Motor Poles Defines the number of motor poles
The motor rated speed and motor rated frequency are used to determine the full load slip of the motor which is
used by the vector control algorithm.
Incorrect setting of this parameter has the following effects:
• Reduced efficiency of motor operation
• Reduction of maximum torque available from the motor
• Reduced transient performance
• Inaccurate control of absolute torque in torque control modes
The nameplate value is normally the value for a hot motor; however, some adjustment may be required when the
drive is commissioned if the nameplate value is inaccurate. Either a fixed value can be entered in this parameter
or an optimization system may be used to automatically adjust this parameter (see Motor Parameter Adaptive
Control (05.016), later in this table).
When Pr 00.042 is set to 'Automatic', the number of motor poles is automatically calculated from the motor Rated
Frequency (00.047), and the motor Rated Speed (00.045).
Number of poles = 120 x (Motor Rated Frequency (00.047 / Motor Rated Speed (00.045) rounded to the nearest
even number.
Pr 00.043 {5.10} Rated Power Factor
Defines the angle between the motor voltage and
current
The power factor is the true power factor of the motor, i.e. the angle between the motor voltage and current. If the
Stator Inductance (05.025) is set to zero then the power factor is used in conjunction with the motor Rated Current
(00.046) and other motor parameters to calculate the rated active and magnetising currents of the motor, which
are used in the vector control algorithm. If the stator inductance has a non-zero value this parameter is not used
by the drive, but is continuously written with a calculated value of power factor. The stator inductance can be
measured by the drive by performing a rotating autotune (see Autotune (Pr 00.040), later in this table).
Powerdrive F300 Getting Started Guide English Iss2.book Page 89 Tuesday, July 28, 2015 3:23 PM
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