Yaskawa P7 Drive User Manual - Manual (Page 108)

Programming 5 - 24
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 when 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).
b8-04 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.
b8-05 Power Detection Filter Time
Setting Range: 0 to 2000 mS
Factory Default: 20 mS
The Energy Saving function will search out the lowest output voltage in order to achieve minimum output power usage.
Parameter b8-05 determines how often the output power (kW) is measured and the output voltage is adjusted.
b8-06 Search Operation Voltage Limit
Setting Range: 0 to 100%
Factory Default: 0%
Once Energy Savings is enabled and the optimal energy saving coefficient value has been set, the programmer can have the
Drive further search out the proper voltage to achieve the lowest output power by making minute changes to the output voltage
and measuring the output power every b8-05 ms. Parameter b8-06 sets limits to the range over which the voltage will be
adjusted in order to minimize the power output. Settings too large a value may allow the motor to stall if the load is applied
abruptly.
If b8-06= 0, then the optimum voltage search operation is disabled (but not Energy Savings itself).
Setting Description
0 Disabled (factory default)
1 Enabled