Soft Starter

Starting large motors in industrial environments requires careful consideration of the starting method to avoid mechanical stress, electrical disturbances, and grid instability. Traditional methods such as Direct-on-Line (DOL), Star-Delta, and Auto Transformer starters are commonly used for low-voltage motors. However, when it comes to medium voltage (MV) and high-capacity motors, these methods often fall short in terms of performance, flexibility, and grid compatibility.

In such applications, reactor-based soft starters—notably FCMA (Flux Compensated Magnetic Amplifier) and HFSR (Harmonic Free Series Reactor) types—have emerged as the preferred technologies. These systems offer smooth, reliable, and energy-efficient motor acceleration while ensuring minimal impact on the electrical network.

FCMA-Based Soft Starters

FCMA soft starters function through the principle of gradually reducing the impedance across the motor circuit during startup. This is achieved using specially designed magnetic amplifiers that regulate voltage without introducing harmonics. The result is a smooth acceleration curve with a significantly reduced starting current—typically as low as 1.5 to 2.0 times the full load current.

Advantages:

No semiconductor components, ensuring long life and high mean time between failures (MTBF)
Suitable for high-inertia and high-duty cycle applications
Minimum maintenance requirements due to passive components
Complete elimination of harmonics in the supply line
Highly customizable and scalable for different load profiles

HFSR (Harmonic Free Series Reactor) Soft Starters

The HFSR soft starter is built around a harmonic-free series reactor designed to limit the initial voltage and current during motor startup. Unlike traditional reactors, HFSR units use a specially engineered air-core reactor design, eliminating the risk of core saturation and associated waveform distortions.

Advantages of HFSR with Air-Core Design:

Harmonic-Free Operation: Designed to avoid harmonic distortion commonly associated with core-type reactors
Air-Core Reactors: No magnetic core, ensuring linear behavior under varying load conditions and eliminating saturation
Thermal Stability: Superior heat dissipation and reduced thermal aging, improving long-term performance
Robustness: Mechanically and electrically durable, ideal for harsh industrial environments
Current Limitation: Capable of reducing starting current to as low as 1.5 times the full load current
Compact and Modular: Flexible installation options tailored to customer site requirements

Industrial Applications

FCMA and HFSR soft starters are extensively used in critical applications across industries such as:

Oil & Gas (pumps, compressors)
Water and Wastewater (large bore pumps)
Steel and Cement (kilns, crushers, conveyors)
HVAC and District Cooling (chillers, blowers)

Their harmonic-free and rugged construction makes them highly suited for grid-sensitive and high-reliability environments.

Conclusion

In applications where voltage quality, reliability, and mechanical protection of the motor are of prime concern, FCMA and HFSR-based soft starters offer a proven, long-life, and maintenance-free solution. With an air-core design that eliminates harmonics and core-related losses, LEPL’s soft starters represent a best-in-class technology for modern industrial motor control.