Optimization; Motor Map Parameters; Open Loop Motor Control - Emerson Powerdrive F300 User Manual

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8

Optimization

This chapter takes the user through methods of optimizing the drive set-up and maximize the performance. The auto-tuning features of the drive
simplify the optimization tasks.
8.1

Motor map parameters

8.1.1

Open loop motor control

Pr 00.046 {05.007} Rated Current
• The rated current parameter must be set to the maximum continuous current of the motor. The motor rated current is used in the following:
• Current limits (see section 8.3 Switching frequency on page 160, for more information).
• Motor thermal overload protection (see section 8.2 Motor thermal protection on page 159, for more information)
• Vector mode voltage control (see Open Loop Control Mode (00.007), later in this table)
• Slip compensation (see Enable Slip Compensation (05.027), later in this table)
• Dynamic V/F control
Pr 00.044 {05.009} Rated Voltage
Pr 00.047 {05.006} Rated Frequency
The Rated Voltage (00.044) and the Rated Frequency (00.047) are used
to define the voltage to frequency characteristic applied to the motor (see
Open Loop Control Mode (00.007), later in this table). The Rated
Frequency (00.047) is also used in conjunction with the motor rated
speed to calculate the rated slip for slip compensation (see Rated Speed
(00.045), later in this table).
Pr 00.045 {05.008} Rated Speed
Pr 00.042 {05.011} Number Of Motor Poles
The motor rated speed and the number of poles are used with the motor rated frequency to calculate the rated slip of induction machines in Hz.
Rated slip (Hz) = Motor rated frequency - (Number of pole pairs x [Motor rated speed / 60]) =
If Pr 00.045 is set to 0 or to synchronous speed, slip compensation is disabled. If slip compensation is required this parameter should be set to the
nameplate value, which should give the correct rpm for a hot machine. Sometimes it will be necessary to adjust this when the drive is commissioned
because the nameplate value may be inaccurate. Slip compensation will operate correctly both below base speed and within the field-weakening
region. Slip compensation is normally used to correct for the motor speed to prevent speed variation with load. The rated load rpm can be set higher
than synchronous speed to deliberately introduce speed droop. This can be useful to aid load sharing with mechanically coupled motors.
Pr 00.042 is also used in the calculation of the motor speed display by the drive for a given output frequency. When Pr 00.042 is set to 'Automatic',
the number of motor poles is automatically calculated from the rated frequency Pr 00.047, and the motor rated speed Pr 00.045.
Number of poles = 120 x (Rated Frequency (00.047) / Rated Speed (00.045)) rounded to the nearest even number.
Pr 00.043 {05.010} Rated Power Factor
The power factor is the true power factor of the motor, i.e. the angle between the motor voltage and current. The power factor is used in conjunction
with the Rated Current (00.046), to calculate the rated active current and magnetising current of the motor. The rated active current is used
extensively to control the drive, and the magnetising current is used in vector mode stator resistance compensation. It is important that this
parameter is set up correctly. The drive can measure the motor rated power factor by performing a rotating autotune (see Autotune (Pr 00.040),
below).
Powerdrive F300 User Guide
Issue Number: 2
Electrical Getting Basic
installation started parameters the motor
Running NV Media Card
Optimization
Operation
Defines the maximum continuous motor current
Defines the voltage applied to the motor at rated frequency
Defines the frequency at which rated voltage is applied
Defines the full load rated speed of the motor
Defines the number of motor poles
Defines the angle between the motor voltage and current
Onboard Advanced Technical
PLC parameters data
Output voltage characteristic
Output
voltage
Pr 00.044
Pr 00.044 / 2
Output
Pr 00.047 / 2 Pr 00.047
frequency
00.042 00.045
⎛
----------------- - × ----------------- -
00.047 =
⎝
2 60
UL listing
Diagnostics
information
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