8
MOTOR CONTROL
8.2.1 Energy Saver (EOC)
The efficiency of a machine is defined as being the ratio between the output mechanical power and the input
electrical power. Remember that the mechanical power is the product between torque and rotor speed, and that
the input electric power is the sum of the output mechanical power and the motor losses.
In the case of the three-phase induction motor, the optimized efficiency is achieved with ¾ of the rated load. In the
region below this point, the Energy Saving function has its best performance.
The Energy Saving function acts directly on the voltage applied on the inverter output; thus, the flux relationship
delivered to the motor is changed so as to reduce the motor losses and enhance the efficiency, consequently
reducing consumption and noise.
P145 P145P134 P134P590P590
P142 P142
P589
P589
Output
frequency (Hz)
Output
frequency (Hz)
Output
voltage (%)
Output
voltage (%)
(a) Voltage in V/f (b) Voltage in quadratic V/f
Figure 8.19: (a) and (b) Example of voltage behavior in V/f and quadratic V/f
The function will be active when the motor load is below the maximum value (P588) and the frequency is above
the minimum value (P590). In addition, in order to prevent the stalling of the motor, the applied voltage is limited to
a minimum acceptable value (P589). The parameter group presented in the sequence defines the characteristics
necessary for the energy saving function.
✓
NOTE!
The use of the energy saving function is recommended in quadratic torque applications (blowers,
fans, pumps and compressors).
P011 - Power Factor
Range: 0.00 to 1.00
Properties: ro
Description:
It indicates the power factor, that is, the relationship between the real power and the total power absorbed by the
motor.
P407 - Motor Rated Power Factor
Range: 0.50 to 0.99
Properties: cfg, VVW
Description:
Setting of the motor rated power factor.
In order to obtain the proper operation of the energy saving function, the motor power factor must be correctly set,
according to the information on the motor nameplate.
8-24 | Micro Mini Drives
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