WEG CFW300 V1.3X, Programming Manual

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V/f Scalar Control
CFW300 | 9-7
9
9.2 START-UP IN V/f MODE
NOTE!
Read chapter 3 Installation and Connection of the CFW300 user manual before installing, energizing
or operating the inverter.
Sequence for installation, verification, power up and start-up.
1. Install the inverter: according to chapter 3 Installation and Connection of the user’s manual, making all the
power and control connections.
2. Prepare and power up the inverter according to section 3.2 Electrical Installation of the user’s manual of the
CFW300.
3. Load the factory default with P204 = 5 (60 Hz) or P204 = 6 (50 Hz), according to the input rated frequency
(power supply) of the inverter used.
4. In order to set a V/f curve different from the default, set the V/f curve using parameters P136 to P146.
5. Setting of specific parameters and functions for the application: program the digital and analog inputs and
outputs, HMI keys, etc., according to the application requirements.
9.3 ENERGY SAVING
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.
(a) Voltage in V/f (b) Voltage in quadratic V/f
P142
Output
voltage (%)
Output
voltage (%)
P590 P590 P145 P145
P142
Output
frequency (Hz)
P134 Output
frequency (Hz)
P591 (%V)
P591 (%V)
Figure 9.8: (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).