The Advantages of Soft Starting in Electric Motors

When an electric motor is switched on directly, it draws a current far above its normal running level and a sudden mechanical jolt occurs. This abrupt start strains the motor, the supply network and the connected mechanical system all at once. To solve this problem, a soft starter is used. Soft starting brings the motor up gradually and provides many advantages. So what are the advantages of soft starting in electric motors?

At DRG Motor, in this article we examine what soft starting is and the benefits it provides. You can find the concepts of motor starting and operation in our article on what an electric motor is.

What Is a Soft Starter?

A soft starter is a device that gradually raises the voltage applied to the motor during start-up. In this way the motor comes online smoothly rather than with a sudden jump. The starting current and mechanical strain are thereby reduced. The soft starter provides a controlled start.

This device protects the motor's life and the health of the connected system. A soft start is part of modern motor control.

Reduction of Starting Current

A motor switched on directly draws several times its rated current. The soft starter, by raising the voltage gradually, noticeably reduces this starting current. Low starting current protects both the motor and the network. This is the most important advantage of soft starting.

Reduced starting current also eases the sudden burden on the electrical installation, which contributes to overall system health.

Prevention of Mechanical Strain

An abrupt start places a mechanical jolt on the motor and the connected equipment. Soft starting eliminates this jolt and provides a gradual, gentle start. In this way belts, couplings, gears and bearings wear less. Mechanical protection is an important benefit of soft starting.

Less mechanical stress extends the life of the entire connected system, which lowers maintenance cost.

Reduction of the Burden on the Network

High starting current can cause sudden voltage drops in the network. This affects other devices connected to the same line. Soft starting limits the starting current and prevents these voltage drops. Network-friendly operation is among the advantages of soft starting.

This benefit is more pronounced especially in plants with many motors. A stable network supports the health of the entire system.

Extension of Motor Life

Each hard start wears the motor's windings and mechanical parts a little more. Soft starting reduces the strain of starting and extends the motor's life. In frequently starting motors, this benefit is far more pronounced. A soft start protects the motor and provides a long life.

A less strained motor runs trouble-free for longer, which is a gain in terms of both cost and continuity.

The Option of a Soft Stop

Soft starters can provide gradual control not only on start-up but also on stopping. A soft stop prevents the motor and the connected system from stopping abruptly. This is important especially in pump systems for preventing water hammer. A soft stop provides additional protection.

The mechanical and hydraulic shocks created by an abrupt stop are prevented with a soft stop, which extends the system's life.

Preventing Water Hammer in Pumps

In pump systems, abrupt starting and stopping leads to water hammer in the pipes. Soft starting brings the motor online gradually and prevents this shock. This protects the pipes and installation. Soft starting provides an important advantage in pumps.

We cover pump motor selection in our article on water pump electric motor selection. A soft start protects the pump system.

Belt Protection in Conveyors

In conveyors, an abrupt start can cause the belt to slip or the carried material to spill. Soft starting sets the belt in motion gradually and prevents these problems. This protects both the belt and production. A soft start is valuable in conveyors.

We explain conveyor motor selection in our article on conveyor and belt motor selection. A soft start protects the belt line.

Suitability for Frequent Starting

In some applications, the motor switches in and out frequently. Because each hard start means strain, soft starting provides a great advantage in frequently starting motors. This reduces the motor's heating and wear. Soft starting suits frequent starting.

In frequently starting motors, soft starting noticeably extends life. This is important in applications such as compressors.

Soft Starter and Frequency Inverter

While the soft starter controls the motor's start, the frequency inverter controls both the start and the running speed. The inverter additionally provides energy savings. According to the application's need, one of these two solutions is chosen. Both offer a soft start.

We explain the advantages of the inverter in our article on the frequency inverter and energy saving. If speed control is needed, the inverter stands out.

Comparison With Star-Delta

Star-delta starting is a traditional method that reduces the starting current; however, a current surge occurs at the moment of transition. A soft starter, by contrast, provides a fully gradual, surge-free start. Soft starting therefore offers a smoother solution. The two methods are chosen according to the application.

A soft starter provides more precise and flexible start control. This makes it advantageous in many applications.

Contribution to Energy Efficiency

Soft starting reduces the needless energy consumption and strain during start-up. Some soft starters can provide additional savings by lowering the voltage at light load. This indirectly contributes to energy efficiency. A soft start supports efficient operation.

Energy savings are an important advantage in continuously running systems. Soft starting is valuable from this angle too.

Its Importance in High-Power Motors

High-power motors draw very high current at start-up and create a large mechanical jolt. Soft starting is therefore almost mandatory in large motors. In these motors, a direct start can seriously damage both the network and the motor. Soft starting protects large motors.

A soft start at high power is critical in terms of both safety and life. This is a standard practice in large motors.

Reduction of Maintenance Cost

Soft starting, by reducing mechanical and electrical strain, also lowers the need for maintenance. Less worn parts mean less maintenance and fewer failures. This provides cost savings in the long run. A soft start is advantageous in terms of maintenance too.

We explain maintenance principles in our article on electric motor maintenance steps. Soft starting reduces the maintenance burden.

In Which Applications Is It Used?

A soft starter is used in many applications such as pumps, fans, conveyors, compressors, crushers, elevators and escalators. Every application where an abrupt start creates problems benefits from soft starting. This gives it a wide field of use. Soft starting is a versatile solution.

The application's starting characteristic determines the need for a soft starter. In the right application, it provides great benefit.

Choosing the Right Starting Method

The right starting method is chosen according to the motor's power, the application's starting need and the speed control requirement. A soft starter is preferred for a gradual start, a frequency inverter for speed control. The right choice ensures efficient and safe motor operation. This choice is made according to the application.

The starting method is a complementary part of motor selection. The right method eliminates starting problems.

Soft Starting and the Right Motor

Soft starting yields the best result when combined with a quality, correctly selected motor. A quality motor is already durable; soft starting guards it against the strain of starting. Together, these two ensure long and safe operation. The right motor and starting method are an ideal combination.

We explain the importance of a quality motor in our article on rotor copper-wound electric motors. Quality and a soft start gain value together.

Adjusting the Start Time

Soft starters offer the ability to adjust the start time according to the application. A heavily loaded application requires a longer start time, while at light load this time can be shortened. An adjustable start ensures the motor comes online in the most suitable way in every application. This flexibility is an important advantage.

The correct start time both protects the motor and meets the application's need. This setting is made by experts.

Torque Control

A soft starter also allows the torque during starting to be controlled. This prevents a sudden torque jolt, especially in sensitive applications. Controlled torque prevents the connected equipment from being damaged. Torque control is an advanced benefit of soft starting.

Sudden torque can cause breakage or damage in the connected system. Controlled torque eliminates this risk.

The Effect on the Electricity Bill

High starting current can increase the demand cost in some tariffs. Soft starting helps lower this cost by reducing the starting current. This provides an indirect energy cost advantage. A soft start is also reflected positively on the bill.

This effect accumulates especially in frequently starting motors. This is an economic benefit of soft starting.

Reduction of Noise and Vibration

An abrupt start creates a noise and vibration jolt. Soft starting eliminates this jolt with a gradual start and provides a quieter start-up. This increases operating comfort. A quiet start is a side benefit of soft starting.

Less vibration also protects the connected equipment, which contributes to the overall health of the system.

Soft Starting in Compressors

Compressors demand high torque and current at start-up, which places them among the applications that benefit from soft starting. A soft start protects the compressor motor and the network from starting strain. This extends the compressor's life. Soft starting is valuable in compressors.

We cover the compressor motor in our article on compressor motor starting torque. A soft start protects the compressor.

Elevators and Moving Systems

Elevators and escalators require a soft start for comfort and safety. An abrupt start is both uncomfortable and strains the mechanical system. Soft starting provides smooth, safe movement in these systems. A soft start is important in these applications.

In applications requiring comfort, soft starting is indispensable. This increases user satisfaction.

Reduction of Heating

High starting current contributes to the motor's heating at each start. In frequently starting motors, this heating accumulates. Soft starting reduces the starting current and limits this heating. This lets the motor run cooler.

We explain the importance of heat control in our article on electric motor temperature control. A soft start also reduces heating.

Installation and Setting

Installing and setting the soft starter correctly maximises its benefit. A wrong setting either makes the start inadequate or weakens the protection. Installation and setting must therefore be carried out by experts. Correct installation ensures the effectiveness of soft starting.

A setting suited to the application ensures the motor comes online ideally, which yields the best result.

Soft Starter Selection

The soft starter is chosen according to the motor's power and the application's starting characteristic. A wrongly sized starter does not provide adequate protection or runs inefficiently. The right choice must be compatible with the motor and suited to the application. This requires expert evaluation.

A correctly matched starter and motor provide the highest benefit. This compatibility is the foundation of the right choice.

Soft Starting and the Efficient Motor

Soft starting, when combined with a high-efficiency motor, provides both energy savings and a long life. The efficient motor uses little energy; the soft start guards it against starting strain. This combination offers the best performance. Together, they are an ideal solution.

We explain the importance of efficiency classes in our article on high-efficiency electric motors. Efficiency and a soft start reward you together.

Contribution to Production Continuity

Soft starting, by protecting the motor and the connected system, reduces unexpected failures. This supports production continuity. Fewer failures mean less downtime and more production. A soft start indirectly contributes to production as well.

A protected system runs without interruption, which is a direct gain for the business.

The Return on the Investment

A soft starter requires an investment; however, it repays this investment by protecting the motor and the connected system. Prevented failures, reduced maintenance and extended life all provide a return. Soft starting is therefore a profitable investment. The protection it provides more than covers its cost.

Especially in large, frequently running motors, this return is fast, which makes soft starting sensible.

The Total Benefit of Soft Starting

In short, soft starting reduces the starting current, prevents mechanical strain, protects the network, extends motor life and lowers maintenance cost. Together, these benefits make soft starting valuable in many applications. In the right application, it provides comprehensive protection. This is an informed choice.

Soft starting is an important component of a modern, efficient motor system, which means a long-term gain.

Expert Support for the Right Solution

Soft starter selection and installation require planning according to the characteristics of the motor and the application. Consulting an expert lets you determine the solution best suited to your application. The right support protects both the motor and the system. Expert evaluation is the key to the right choice.

At DRG Motor, we offer technical support in soft starting solutions. The right solution extends your motor's life.

DRG Motor for Soft Start Solutions

At DRG Motor, we offer quality, durable motors that work in harmony with soft starters and frequency inverters. Our aim is to protect your motor from starting strain and ensure long-lived operation. According to your application's starting need, we recommend the most suitable starting solution.

To select a motor suited to soft starting and to receive technical support, you can contact DRG Motor and explore our range on the products page, or visit our home page. Soft starting is a smart choice that extends the life of your motor and your system.