How LV Soft Starters Reduce Inrush Current and Extend Motor Life

Electric motors are essential to industrial infrastructure. Pumps, compressors, fans, blowers and process equipment all depend on motors that can start reliably and reach operating speed without placing unnecessary stress on the electrical network or mechanical system.

The challenge is that motor starting can create a short-duration current significantly higher than normal operating current. This sudden demand can contribute to voltage disturbance, mechanical shock and accelerated wear if it is not properly controlled.

A low voltage soft starter helps manage this process by controlling the way voltage and current are applied during motor acceleration. Rather than allowing the motor to start abruptly, the soft starter reduces the electrical and mechanical impact of the starting cycle.

Lecon Energetics' LV FCMAplus Soft Starter is one example of this approach. The system uses an air-core series reactor architecture and is designed for motor applications including pumps, compressors, fans and blowers. It is available for 415V and 690V systems and motor ratings up to 2,000kW.

Why Motor Starting Current Matters

When a motor starts directly across the line, it can draw several times its normal full-load current.

This temporary increase is known as inrush or starting current.

Although the high current usually lasts only during acceleration, it can affect both the motor and the wider electrical system. Depending on the network and motor size, high starting current may contribute to voltage drop, heating and increased electrical stress.

Mechanical equipment can also experience a rapid increase in torque.

Pumps, couplings, belts, gearboxes and driven machinery may all be exposed to sudden forces when the motor accelerates too quickly.

This is why soft starters for motors are often evaluated not only for electrical current control but also for smoother mechanical acceleration.

How an LV Soft Starter Controls Starting Current

A soft starter limits the electrical conditions applied to the motor during the starting period.

Lecon's LV FCMAplus system uses air-core based series reactors as part of the motor-starting arrangement. The solution is designed specifically around motor and load characteristics, with factors such as torque-speed curves, current-speed behaviour and moment of inertia considered during engineering.

This customised approach is important because motors do not all start under the same load conditions.

A centrifugal pump can have a different starting profile from a compressor or heavily loaded conveyor. The motor soft start controller therefore needs to be matched to both the motor and the driven equipment.

Starting Current Can Be Reduced Substantially

Lecon states that its standard LV FCMAplus models are designed for a starting current of approximately 3 to 3.5 times full-load current.

For applications requiring greater current limitation, a Dynamic Compensator can reduce starting current to approximately 1 to 1.5 times full-load current, according to the manufacturer's current product data.

This provides an important engineering option where the available electrical network cannot comfortably support a high motor-starting demand.

Reducing the starting current can help minimise voltage disturbance while enabling larger motors to start on a constrained supply system.

The appropriate limit still needs to provide enough motor torque for the connected mechanical load to accelerate successfully.

Current Reduction and Starting Torque Need to Be Balanced

Lower starting current is not automatically better in every application.

A motor requires sufficient torque to overcome the inertia and resistance of the driven equipment. If current is reduced too aggressively, the motor may accelerate too slowly or fail to reach normal operating speed.

This is why the starting arrangement should be designed using the complete motor and load characteristics.

Lecon notes that its FCMAplus systems are customised by analysing motor torque-speed curves, load torque-speed curves, current-speed characteristics and moment of inertia.

For an adjustable soft starter, this balance between current limitation and adequate accelerating torque is one of the most important design considerations.

Smooth Starting Can Reduce Mechanical Stress

The benefit of controlled starting extends beyond the electrical network.

An abrupt motor start can produce mechanical shock through the motor shaft and connected equipment.

In pumping systems, sudden acceleration may also contribute to hydraulic disturbances. Conveyors can experience belt and coupling stress, while compressors and fans can place additional loading on mechanical drive components.

A correctly engineered soft-start sequence allows motor speed and torque to increase more gradually.

This can reduce the shock experienced by:

• couplings
• gearboxes
• shafts
• belts
• bearings
• pump systems
• connected process equipment

Over repeated operating cycles, reducing these stresses can help limit unnecessary wear.

Soft Starting Can Support Longer Equipment Life

Motor life is influenced by many factors, including operating temperature, loading, insulation condition, maintenance and supply quality.

Starting conditions are another contributor.

A motor that starts frequently can be exposed to repeated thermal and mechanical stress. Where each start involves excessive current and sudden torque, these effects can accumulate over time.

A soft starter cannot eliminate normal motor ageing, but controlling the starting cycle can reduce one source of repeated stress.

The same principle applies to the driven machinery.

Smoother acceleration can help protect mechanical components that would otherwise experience repeated shock loads whenever the motor starts.

Soft Stopping Can Also Be Important

Some motor applications benefit from controlled stopping as well as controlled starting.

Pumps are a common example.

An abrupt stop can change fluid velocity rapidly, potentially contributing to pressure transients in the system. A controlled stop can help reduce the severity of this change depending on the application.

The broader objective is to manage the motor transition between stopped and running conditions in a more controlled manner.

This is why LV soft starters are often considered as part of the complete motor-control philosophy rather than only as a way to reduce start current.

Why Pumps, Fans, Blowers and Compressors Are Common Applications

Lecon lists pumps, compressors, fans and blowers among the principal applications for its LV FCMAplus Soft Starter.

These applications are common across water infrastructure, HVAC, manufacturing, oil and gas facilities and industrial processing.

Large pumps, for example, may operate on electrical networks where uncontrolled starting current could create an undesirable voltage dip.

Fans and blowers often use motors with significant inertia, while compressor starting conditions can depend strongly on the mechanical process.

A soft-starting solution can be engineered according to these different load characteristics.

The FCMAplus Approach Uses Air-Core Series Reactors

The Lecon system differs from conventional electronic soft starters that rely primarily on semiconductor switching.

The LV FCMAplus uses air-core, vacuum-pressure epoxy-impregnated reactors with electrolytic copper conductors. The system is designed according to IEC 60076-6 and is air cooled.

The published technical specifications include:

• 415V or 690V input voltage
• motor ratings up to 2,000kW
• 50Hz or 60Hz frequency
• indoor installation
• operating temperature from 0°C to 55°C
• Class F insulation or customised insulation
• five-tap reactor design with 5% voltage difference at each tap

These characteristics position the system for a wide range of industrial low-voltage motor-starting applications. (Lecon Energetics Private Limited)

Bypass Operation Reduces Losses After Starting

A soft starter primarily performs its function during motor acceleration.

Once the motor has reached normal operating speed, it is generally desirable to remove the starting impedance from the circuit.

Lecon provides its LV FCMAplus systems with a bypass device, which can be either a power contactor or an air circuit breaker depending on the customer's preferred arrangement.

After starting is complete, the bypass carries normal motor current.

This helps avoid unnecessary continuous losses through the starting reactor during normal operation.

Complete Motor Feeder Integration Is Possible

In some installations, the soft starter is only one part of a wider motor feeder.

Lecon states that complete systems can be supplied with an air circuit breaker or power contactor, motor-protection relay and metering for switching and protection functions.

This type of integrated arrangement can simplify motor-control planning because starting, switching, protection and monitoring can be considered together.

It also reinforces the importance of viewing a motor soft start controller as part of the complete motor feeder rather than as an isolated component.

PLC and HMI Automation Add Control Flexibility

Modern motor-control systems increasingly incorporate automation and remote monitoring.

Lecon's LV soft starters are automated using a PLC with HMI, supporting system control and remote technical assistance.

For industrial facilities, automation can support clearer operating sequences, alarm handling and integration with wider control systems.

The specific level of plant integration depends on the project, but PLC-based control can provide more flexibility than a purely manual starting arrangement.

When Is an LV Soft Starter Particularly Useful?

A soft starter can be considered where direct-on-line starting creates unacceptable electrical or mechanical effects.

Typical situations may include:

• large motors on relatively weak electrical networks
• applications with high starting frequency
• pumps where abrupt acceleration should be limited
• fans and blowers with significant inertia
• compressors requiring controlled acceleration
• installations where mechanical shock affects equipment life
• projects where reducing voltage dip during motor start is important

The decision should still be based on motor data, load characteristics and the electrical network.

A soft starter is not automatically required for every motor.

Soft Starter or Variable Frequency Drive?

Soft starters and variable frequency drives are sometimes considered for similar motor applications, but their primary functions differ.

A soft starter mainly manages the starting and stopping period. Once the motor reaches normal speed, the starter is typically bypassed and the motor operates at line frequency.

A variable frequency drive controls both motor voltage and frequency and can regulate motor speed continuously during normal operation.

If the application requires only controlled starting and stopping, a low voltage soft starter may provide a more focused solution.

If continuous speed control is required, a variable frequency drive may be more appropriate.

The choice should depend on the process requirement rather than assuming one technology is universally better.

Motor Starting Technology at Middle East Energy 2026

Motor control and energy-management technologies will form part of the wider electrical infrastructure discussion at Middle East Energy 2026, scheduled for 1–3 September 2026 at Dubai World Trade Centre, UAE. The event covers electrical infrastructure, energy consumption and management, critical power and related technology sectors.

Dutco Tennant LLC is one of the soft starter suppliers, scheduled to exhibit at Hall H5, Stand D10, with Lecon Energetics' FCMAplus Low Voltage Soft Starter included in its Middle East Energy 2026 technology portfolio. Dutco Tennant identifies pumps, compressors, conveyors, fans, water-treatment facilities and industrial processing equipment among the relevant application areas.

For utilities, industrial operators, EPC contractors and electrical engineers, the exhibition provides a useful setting for examining how motor-starting technology can help address electrical and mechanical stresses associated with large industrial motors.

As motor-driven systems continue to support critical industrial processes, controlling how those motors start can play an important role in equipment reliability. By limiting inrush current, managing acceleration and reducing mechanical shock, LV soft starters can help create a more controlled transition from standstill to normal operation.

Dutco Tennant LLC provides solution for civil engineering market by offering pipes, potable water valves, waste water valves, surveying equipments, and waste water treatment solution.