Due to transport sugar juice/ clean water /cooling water/ massecuite and wastewater, there are many pumps in the sugar factories. Pumps are characterized by high reliable require¬ments and fairly high dynamics during load changing. They normally make the biggest contribution to a plant's own energy consumption.
With today's VFD technology, those pumps can be efficiently controlled and will not compromise its reliability. Furthermore, mechanical mainte¬nance costs can be reduced by controlling the water flow with VFDs instead of throttling valves or hydraulic couplings.
Fig.1 Power consumption for various pump control methods
Fig.2 Comparison of investment costs and energy losses among different control methods
The advantage of INVT VFDs driving:
1.Significant energy savings
Normally in the sugar factory, they use pumps for loads. But almost all of the pumps were directly driven by grid power. The speed of running pump can’t change. Actually, these pumps do not always run at rated speed. With VFD, pumps can run at optimum operating condition. So there is significant energy saving. From site running date, some pumps energy saving can do 60%.
VFDs build in PID function which can keep the pressure of water or juice stable. It is better for piping and can reduce the loss of shutdown maintenance, save plenty of maintenance costs and increase the lifetime of pumps.
3.More protection for pumps
There is plenty of motor protection, such as overcurrent/overvoltage/overheat. It can protect the motor better.
The starting current of direct-on-line started electric motor is six times that of the nominal current. This will cause a voltage drop and disturb the process, especially when the supply network is weak.
Starting with VFDs are Controlled and smooth start-up.
Fig.3 Pumps with INVT VFDs