Yaskawa F7 Drive Programming Manual - Manual (Page 33)

Programming 25
b8 Energy Savings
The energy savings function improves overall system operating efficiency by operating the motor at its highest efficiency. This
is accomplished by continuously monitoring the motor load and adjusting the motor terminal voltage so that the motor always
operates near its rated slip frequency. A motor is most efficient when operating near rated slip conditions.
b8-01 Energy Savings Selection
When the Energy Savings function is enabled (b8-01= “1: Enabled”), the Drive reduces the output voltage to the motor below
the voltage value specified by the programmed V/f pattern whenever the motor load is light. Since torque is reduced during
this voltage reduction, the voltage has to return to normal levels once the load returns. The energy savings is realized through
improved motor efficiency. The reduced output voltage causes increased rotor slipping even with a light load. A motor is most
efficient when operating fully loaded (i.e. operating at rated slip).
b8-02 Energy Saving Control Gain
Setting Range: 0.0 to 10.0
Factory Default: 1.0
The output voltage during energy saving operation is the product of the normal V/f settings (E1-03 to E1-13) and the energy
saving gain. The output voltage decreases and recovers according to the energy saving control filter time constant b8-03. As
the energy saving gain increases, the output voltage increases also.
Note: When parameter A1-02 = 2 (Open Loop Vector) the factory default setting is 0.7. When parameter A1-02 = 3 (Flux
Vector) the factory default setting is 1.0.
b8-03 Energy Saving Control Filter Time Constant
Setting Range: 0.00 to 10.00
Factory Default: Model Dependent
Parameter b8-03 sets the response time of the energy saving function. Decreasing this setting will cause the response to
become quicker; however, instability may occur if it is decreased too much.
Note: For Drive models F7U2055 to 2100 and F7U4055 to 4300 the factory default setting is 2.00 when parameter A1-02 = 2
(Open Loop Vector) and 0.05 when parameter A1-02 = 3 (Flux Vector). For all other Drive models the factory default
setting is 0.50 when parameter A1-02 = 2 (Open Loop Vector) and 0.01 when parameter A1-02 = 3 (Flux Vector).
b8-04 Energy Saving Coefficient Value
Setting Range: 0.0 to 655.0
Factory Default: Model Dependent
Parameter b8-04 is used in maximizing motor efficiency. The factory setting will be Drive capacity dependant but can be
adjusted in small amounts while viewing the kW monitor (U1-08) and running the Drive to minimize the output kW. A larger
value typically results in less voltage to the motor and less energy consumption. Too large a value will cause the motor to stall.
Setting Description
0 Disabled (factory default)
1 Enabled