When is a soft starter the optimal solution and when do you benefit from a frequency converter? A comprehensive comparison for machine builders and plant operators.
When is a soft starter the more economical choice compared to a frequency converter?
A soft starter is often the more economical solution, when no variable speed control is needed during operation and the focus is on a gentle motor start as well as the reduction of inrush currents and mechanical stresses . This is particularly true for applications with constant loads and infrequent starts.
What is the main advantage of a frequency converter compared to a soft starter?
The crucial advantage of a frequency converter is the precise and stepless control of motor speed over the entire operating range. This allows for an optimal adaptation to process requirements, resulting in significant energy savings of often 30% to 60% especially with variable load profiles.
Can soft starters control the speed of a motor during operation?
No, soft starters are primarily designed for the starting and stopping process. They reduce the voltage at start-up, to bring the motor gently to nominal speed. A continuous speed control during operation is not possible with a standard soft starter ; a frequency converter is required for that.How do soft starters and frequency converters affect the lifespan of motors and mechanical components?
Wie wirken sich Softstarter und Frequenzumrichter auf die Lebensdauer von Motoren und mechanischen Komponenten aus?
Both devices contribute to protection. Soft starters reduce mechanical shocks and current spikes at start-up. Frequency converters provide additionally through controlled acceleration and deceleration ramps as well as the ability to adjust speed to the load, a more comprehensive protection, which can extend the lifespan of the motor, gearboxes, and the entire system..
What acquisition costs should I expect for frequency converters compared to soft starters?
Frequency converters generally have higher acquisition costs, they are often two to three times more expensive than soft starters of comparable power. However, this additional investment can pay off through energy savings, reduced mechanical wear, and improved process control often within 1 to 3 years..
Do frequency converters generate disturbances in the power grid that need to be considered?
Yes, frequency converters can generate electromagnetic interference (EMI) . To avoid impairments to other electronic devices or the power grid, measures such as the use of power filters, shielded cables, and proper grounding are often necessary. Maßnahmen wie der Einsatz von Netzfiltern, geschirmten Kabeln und eine fachgerechte Erdung notwendig.
How does the maintenance effort differ between soft starters and frequency converters?
Soft starters are generally lower in maintenance due to their simpler electronic structure and fewer components. Frequency converters, on the other hand, contain wear parts like. Frequenzumrichter hingegen enthalten Verschleißteile wie fans and power capacitors, which require regular inspections and possibly preventive replacement , to ensure high availability.
For which typical applications in industry are soft starters particularly suitable?
Soft starters are excellently suited for applications with constant operating speed, where a gentle start and stop to reduce mechanical stresses and inrush currents is a priority. Examples include pumps, fans, compressors, conveyors, and agitators, which do not need to be continuously controlled in speed.
The decision between soft starters and frequency converters is application-specific: soft starters are optimal for gentle starting in constant speed applications and can reduce inrush currents by up to 70%, while frequency converters enable precise speed control, und energy savings of up to 60% with variable loads.
Although frequency converters higher acquisition costs cause (often 2-3 times higher than soft starters), they can compensate for this through significant energy savings und reduced mechanical wear often within 1 to 3 years., leading to lower overall operating costs.
Both technologies protect mechanical components like gearboxes and couplings. Frequency converters provide a more comprehensive protection through continuous adjustment of speed and torque and can extend the machine lifespan by up to 20%and improve process quality. contact our experts now.
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Introduction to soft starters and frequency converters.
Find out which drive is best suited for your application: soft starter or frequency converter. We compare costs, benefits, and areas of use.
Are you facing the decision of whether a soft starter or a frequency converter is the better choice for your drive technology? The answer depends on your individual requirements. For personal consultation and tailored solutions, please soft starters and frequency converters The choice between
soft starters and frequency convertersis crucial for drive efficiency. This article compares both drive controllers and assists in selecting for specific requirements.
In conveyor systems, the question arises: Soft starter for gentle starting or speed controller for speed control? The right choice reduces operating costs and can extend machine lifespan by up to 20%. Machine builders for packaging systems often make this decision. Understanding modern drive technology.
The aim of this article is to provide a detailed overview of soft starters (also known as soft starting devices) and frequency converters (often referred to as inverters) to illuminate their respective advantages and disadvantages and provide decision support for selecting the optimal solution based on specific application requirements.
Understanding technical nuances is essential for an economical decision. The most advanced solution is not always the optimal one. For simple pump applications with constant loads, a soft starter can save costs. See also: frequency converters how it works in detail.Functionality and technology
soft starters: Basics and functionality.
Soft starting devices enable gentle motor starting by reducing the motor voltage during start-up using thyristors, which limits inrush current and torque spikes. This protects mechanical components such as gearboxes and couplings. As a result, the load on a centrifuge during start-up can drop by over 60%. Basics for three-phase motors.
- soft starters reduce the motor voltage at start-up through thyristors.
- They limit inrush currents and torque spikes.
- This leads to the protection of mechanical components such as gearboxes and couplings.
- The mechanical load can be significantly reduced, for example by over 60% in centrifuges.
- frequency converters convert line frequency and voltage for precise motor control.
- They allow for stepless regulation of speed and torque.
- Frequency converters are ideal for variable speeds and can save energy (e.g., up to 50% in fans).
frequency converters: Basics and functionality.
frequency converters control motors precisely by converting grid frequency and voltage into variable values. This enables stepless speed and torque control, ideal for variable speeds. Fans in air conditioning systems then adjust their output and save up to 50% energy. More on motors with frequency converters.Advantages and disadvantages in detail
Advantages of soft starters.
For applications without the need for variable speed, such as simple conveyors, soft starters are cost-effective, with up to 30% lower acquisition costs compared to frequency converters of the same power class. Their compact design facilitates integration into existing panels. Another advantage is the reduction of current spikes at start-up by up to 70%.
Disadvantages of soft starters.
A significant disadvantage of soft starters is the lack of continuous speed control during operation. After start-up, the motor runs at nominal speed. For applications requiring variable speeds, such as dosing pumps, they are soft starters unsuitable. Their protective functions are often more limited.
Advantages of frequency converters.
frequency converters allow significant energy savings, often between 30% and 60%, by adjusting the motor speed to the process requirements. This applies to pumps and fans with variable loads. A 50 kW pump with FU (frequency converter) can reduce energy costs by thousands of euros annually. They help comply with EU efficiency regulations (ecodesign).
Disadvantages of frequency converters.
The acquisition costs for speed controllers are often significantly higher than those for soft starters, and their installation can be more complex. They can cause EMI, requiring filtering measures. Long motor leads often need shielded cables or output filters, increasing costs by 10-15%.Areas of application and selection criteria
Typical areas of application for soft starters.
Soft starting devices are ideal for applications with fixed speed, where the focus is primarily on reducing mechanical stresses and inrush currents. Examples include compressors that do not start against high pressure, or agitators, where a gentle start means material preservation. For a conveyor belt in a gravel pit with few starts per day, a soft starters is often the most economical solution. Discover motors for conveyors.
- soft starters are ideal for applications with fixed speed to reduce mechanical stresses.
- Typical examples for Soft starter-applications are compressors, agitators, and conveyors.
- frequency converters are the first choice when precise speed and torque control is needed.
- Application examples for Frequency converters are machine tools, extruders, and precise filling systems.
- The main selection criterion is the need for variable speed control during operation.
- Other criteria include starting frequency, control accuracy, and budget.
- Converters can improve product quality, for example in extrusion by up to 10%.
Typical areas of application for frequency converters.
frequency converters are the preferred choice when precise speed and torque control is required, for example in machine tools, extruders, or precision filling systems in the food industry. They are also advantageous for pumps and fans, where energy efficiency through speed adjustment is a priority. A speed controller can precisely control the speed of an extruder, thereby improving product quality by up to 10%. For variable-speed gear motors they are often integrated.
Selection criteria: Which type when?
The central question in deciding between soft starters and frequency converters is the need for variable speed control in operation. If this is required, usually a frequency converters is necessary. Other criteria include the frequency of starts, the required control accuracy, and the budget. For a simply running water pump, a soft starter may be sufficient, while an HVAC system with variable air volume control benefits from a Frequency converters .Energy efficiency and economic efficiency
Energy efficiency: soft starters vs. frequency converters.
frequency converters offer the greatest energy-saving potential through demand-based speed adjustment, often up to 60% with variable loads. Soft starting devices consume energy for voltage reduction primarily during the start-up phase; thereafter, they are often bypassed, and the motor runs with mains voltage. A soft starters with bypass can achieve an efficiency of over 99.5% in continuous operation. The direct comparison of energy efficiency between these motor controls depends on the application.
Economic considerations.
Although frequency converters have higher acquisition costs (sometimes 2-3 times higher than soft starters), they often pay off through energy savings and reduced mechanical wear within 1 to 3 years. A Total Cost of Ownership (TCO) analysis is crucial. For applications with few operating hours per year and low control requirements, a soft starters is usually more economical. For example, a 22kW fan with 4000 operating hours/year can achieve annual savings of around €800 through a frequency converters .Integration and maintenance
Integration into existing systems.
Both soft starters and frequency converters are designed for integration into industrial automation systems and offer interfaces such as Profibus or Ethernet. ATEK Drive Solutions assists with the seamless drive system integration. A new Frequency converters can often process the control signals of an older PLC. However, compatibility with existing sensors and actuators must be checked in advance.
Maintenance and lifespan.
Soft starting devices are generally more maintenance-friendly due to their simpler design; occasional cleaning and checking of connections is often sufficient. frequency converters contain more wear parts such as fans (lifespan about 20,000-40,000 hours) and capacitors (lifespan about 5-10 years), which require regular inspections and preventive replacement. An unplanned failure of a converter can cause production costs of several thousand euros per hour.
Find out which drive is best suited for your application: soft starter or frequency converter. We compare costs, benefits, and areas of use.
Are you facing the decision of whether a soft starter or a frequency converter is the better choice for your drive technology? The answer depends on your individual requirements. For personal consultation and tailored solutions, please soft starters and frequency converters depends significantly on the specific application requirements. speed controller offer comprehensive control options and high energy efficiency, while soft starter are compelling for applications with fixed speed due to lower costs and easier maintenance. A careful consideration of these starting and regulation devices optimizes drive technology. For individual advice on your drive solution, we are available.
