Medium Voltage Soft Starter Solution for Controlled Pump Starting in Desalination Plants

Application: Desalination Plant Pump Systems

The Via Maris desalination plant in Palmachim Industrial Park, Israel, required a reliable and controlled motor starting solution for critical seawater pumping operations. The installation includes eight medium voltage motors rated at 3000 kW, 6.6 kV, and 3000 RPM, with TEWAC construction, driving high-capacity pumps within the desalination process.

In desalination applications, precise control of pump operation during startup is essential to maintain process stability and protect infrastructure. The system must ensure a controlled increase in water pressure to prevent damage to piping and membrane filtration systems.

Challenge: Controlling Motor Starting and Pressure Increase

The desalination plant imposed strict operational and engineering constraints on the motor starting process:

• The water pressure increase rate during startup was limited to 1 bar per second to protect piping systems and membranes
• High-power motors required controlled acceleration to prevent excessive starting current and thermal stress
• The system required high accuracy, with a maximum deviation of ±3% in acceleration rate
• Extended starting times of up to 300 seconds had to be supported
• Integration with an auxiliary booster water turbine, accelerating the motor to approximately 60% speed, required coordinated control

These conditions required a closed-loop motor starting solution capable of maintaining precise acceleration and pressure control throughout the startup sequence.

Solution: Closed-Loop Medium Voltage Soft Starter with Encoder Feedback

Solcon-IGEL supplied and commissioned eight medium voltage soft starter systems designed for controlled motor starting in desalination pump applications.

The solution is based on a closed-loop soft starter system, using real-time feedback from a 100 PPR digital encoder installed on the motor shaft. This enables continuous monitoring and adjustment of motor speed during startup.

Key Technical Features

• Closed-loop motor control ensuring precise acceleration and pressure regulation
• Digital encoder feedback integration for accurate speed monitoring
• Controlled starting current, maintained at approximately 2.5 PU
• Extended ramp capability supporting starting times up to 300 seconds
• High-precision control, maintaining acceleration deviation within ±3%
• Coordinated operation with auxiliary turbine-assisted acceleration

This configuration ensures that both electrical and mechanical stresses are minimized while maintaining strict process requirements.

Results: Stable Motor Acceleration and Controlled Pressure Ramp-Up

Field commissioning results confirmed the effectiveness of the medium voltage soft starter solution:

• Uniform increase in motor speed and three-phase current, ensuring smooth startup behavior
• Controlled pressure increase, maintained below specified limits throughout the starting sequence
• Accurate tracking of the required acceleration profile, within defined tolerance levels
• Reduced thermal stress on motors, due to controlled starting current
• Improved system reliability and protection of piping and membrane systems

The system successfully achieved all design objectives, delivering a stable and repeatable motor starting process for desalination applications.

Technical Summary: Medium Voltage Soft Starter for Desalination Pumps

• Application: Desalination plant pump systems
• Motor rating: 3000 kW, 6.6 kV, 3000 RPM
• Motor type: TEWAC
• Number of soft starters: 8
• Control method: Closed-loop with digital encoder feedback (100 PPR)
• Starting current: ~2.5 PU
• Starting time: Up to 300 seconds
• Acceleration accuracy: ±3%
• Pressure control requirement: ≤ 1 bar/sec

Medium Voltage Soft Starters for Desalination Applications

Medium voltage soft starters provide a reliable solution for controlled motor starting in desalination plants, where pump systems require precise acceleration, reduced electrical stress, and stable pressure control.

By integrating closed-loop control and real-time feedback, these systems enable safe and efficient startup of high-power motors, ensuring long-term operational reliability in critical water treatment processes.