A: There are 3 parameters P22.24~P22.26 are used for setting the conditions of reduce motor:
1. P22.24 pressure allowance 100% is corresponding with P09.02.
2. If variable frequency motor runs frequency reach P22.20, and (PID feedback [P17.24] - PID given[17.23]) > Pressure allowance [P22.24]), this status keep time reach P22.26, meet condition of reduce motor.
3. P22.25 a limit frequency to reduce motor. When the system still have power freq. motor, and VFD output reach this P22.25, keep time reach P22.26, start to reduce the power freq. motor.
4. Also when added a power freq. motor, VFD also output this setting frequency P22.25, then adjust by PID, avoid pipe pressure fluctuation.
5. When reduce motor, VFD operate the relay to switch-off power freq. motor, at the same time, increase output frequency to P22.20 with P22.28 ACC time(if P22.27=1), then adjust output frequency by PID. In order to avoid pipe pressure fluctuation.