The use of variable speed drives (VSDs) for flow and pressure control of electric motors results in significant energy and cost savings. In addition, VSDs provide soft starting features, which improve system reliability.
Flow and pressure control
Water consumption varies greatly during a day. Consequently, pumps often run at partial load. By controlling the flow and pressure of pumps with VSDs the pumps will operate at maximum efficiency under a variety of flow conditions, considering the actual need.
A pump, controlled by a VSD, running at half speed consumes only about one-eighth of the energy compared to one running at full speed.
Soft starting
VSDs also act as soft starters reducing the stress on network, motors and pumps. During the starting process, the VSD progressively increases the motor speed and smoothly accelerates the load to its rated speed.
Soft starters eliminate high starting currents and voltage dips which can cause process trips. With soft starters, maintenance costs will be reduced and the lifetime of the equipment extended.
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| 1 | High speed for high capacity | • Maximum capacity
• Best productivity |
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| 2 | Precise and optimal speed | • Best Efficiency Point (BEP) of pumps
• Increased lifetime of equipment |
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| 3 | Soft start of motor | • No network voltage dips
• Reduced mechanical stress |
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| 4 | Low speed for low capacity | • Best energy efficiency
• Reduced operating costs |
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| 5 | Soft stop of motor | • No water hammering
• Reduced mechanical stress |
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Fields of application
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| Clean water applications | Pumps for water extraction, transmission, treatment and distribution (incl. Electrical Submersible Pumps) |
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| Water sewage applications | Pumping stations and treatment plants |
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| Desalination plants | Raw water, process and high pressure pumps |
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| Industrial applications | Pumps for cooling water supply and condensation |
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| Others | Irrigation and water lifting / storage and district heating pumps |
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