Permanent Magnetic VSD Screw air compressor APM series

Variable Speed Screw Air Compressors with Permanent Magnet Motors

The APM series variable speed screw air compressors combine permanent magnet motors with inverter control, allowing compressor output to adapt to actual compressed air demand. Instead of operating continuously at maximum speed, the system regulates motor speed according to the required air delivery.

This operating principle is particularly suitable for facilities where compressed air consumption changes throughout the working day. Typical examples include production lines with different operating modes, CNC machines, pneumatic tools, metalworking equipment and automated manufacturing processes.

When correctly sized, a variable speed screw air compressor can reduce unloaded operation, limit sudden pressure fluctuations and provide a better balance between the amount of compressed air produced and the amount actually consumed.

Models from 7.5 to 75 kW

The APM series includes nine main power ratings covering different levels of compressed air demand:

• SCR10APM – 7.5 kW;
• SCR15APM – 11 kW;
• SCR20APM – 15 kW;
• SCR30APM – 22 kW;
• SCR40APM – 30 kW;
• SCR50APM – 37 kW;
• SCR60APM – 45 kW;
• SCR75APM – 55 kW;
• SCR100APM – 75 kW.

The smaller models are suitable for workshops, individual machines and local pneumatic systems. Compressors in the 22–45 kW range can supply larger production areas and groups of machines, while the 55 and 75 kW models are intended for installations with higher and more continuous compressed air demand.

Selection should not be based on motor power alone. The required air delivery, operating pressure, peak consumption and possible future expansion of the pneumatic system should also be considered.

Free Air Delivery from 0.43 to 12.2 m³/min

The APM variable speed screw air compressors cover an overall free air delivery range from 0.43 to 12.2 m³/min. The actual output depends on both the selected motor power and the required working pressure.

For example, the 7.5 kW SCR10APM provides up to 1.15 m³/min at 7 bar. The 37 kW SCR50APM delivers up to 6.2 m³/min, while the largest SCR100APM model reaches up to 12.2 m³/min at 7 bar.

As working pressure increases, maximum air delivery generally decreases. The compressor should therefore be selected according to the required combination of pressure and air flow, rather than only according to the highest capacity stated for the series.

Working Pressure from 7 to 16 Bar

Depending on the model, APM compressors are available in configurations for 7, 8, 10, 12.5, 13, 15 and 16 bar. Not every motor power is available with every pressure configuration.

The SCR10APM and SCR40APM models are primarily available in versions up to 10 bar. The SCR50APM, SCR60APM, SCR75APM and SCR100APM include configurations up to 12.5 bar. The SCR15APM, SCR20APM and SCR30APM ranges also include higher-pressure versions reaching 15 or 16 bar.

How to Determine the Required Working Pressure

The compressor working pressure should be matched to the requirements of the connected machines and pneumatic tools. Pressure losses through pipelines, filters, dryers and other compressed air treatment equipment should also be taken into account.

Selecting a significantly higher pressure than necessary is not recommended, as it can increase energy consumption and reduce the available air delivery. The correct approach is to determine the pressure required at the point of use and then allow a reasonable margin for actual pressure losses within the system.

Advantages of VSD Control

The main advantage of VSD technology is its ability to adjust compressor output according to current air demand. This is important in systems where the number of operating machines and the required air flow change throughout the working day.

Variable speed control supports:

• smooth regulation of motor speed;
• more stable system pressure;
• fewer frequent load and unload cycles;
• reduced operation without useful compressed air production;
• adjustment to fluctuating compressed air demand;
• smoother motor starting.

Actual operating efficiency depends on correct compressor sizing, the facility’s consumption profile and the condition of the entire compressed air system. Variable speed control cannot compensate for an incorrectly sized compressor, unnecessarily high pressure settings or significant air leakage.

Applications of APM Screw Air Compressors

The compressors in the APM series can supply a wide range of industrial compressed air consumers and pneumatic equipment. Typical applications include:

• CNC machining centres;
• metalworking machines and production lines;
• pneumatic tools;
• automated manufacturing lines;
• assembly and packaging machines;
• industrial workshop equipment;
• pneumatic control and automation systems;
• centralised compressed air installations.

For applications with specific compressed air quality requirements, the compressor should be combined with suitable filters, an air dryer, an air receiver and an appropriate condensate drainage system.

How to Select a Variable Speed Screw Air Compressor

Determine the Actual Compressed Air Demand
Calculate the rated air consumption of all machines that may operate simultaneously. For consumers that operate intermittently, their actual duty cycle should be considered rather than only the maximum value stated in the technical documentation.

Check Peak Air Consumption
Average air demand is not always sufficient for correct compressor sizing. The simultaneous start-up of several machines can create a short-term pressure drop. In such cases, maximum instantaneous consumption and the required air receiver capacity should also be evaluated.

Select the Correct Working Pressure
The lowest pressure at which the connected equipment can operate reliably should be selected. A reasonable allowance should be made for pressure losses without sizing the compressor for unnecessarily high values.

Allow for Reserve Capacity Without Oversizing
A moderate capacity reserve can support future expansion and compensate for temporary consumption peaks. However, an excessively large compressor may operate outside its optimum range for long periods. The selected model should work efficiently under the facility’s normal operating conditions.

Check the Installation Conditions
The compressor dimensions and weight, access for service and maintenance, room ventilation, ambient temperature and connection size should all be considered when planning the installation.

Consultation for Selecting an APM Series Compressor
Correct compressor selection requires information about the required working pressure, average and peak air consumption, the number of connected consumers and their operating schedule. This information can be used to determine the appropriate compressor model and the additional equipment required for compressed air treatment and storage.

Contact our team for technical consultation and assistance in selecting a variable speed screw air compressor according to the requirements of your pneumatic system.

Frequently Asked Questions

What is a variable speed screw air compressor?

A variable speed screw air compressor uses a frequency inverter to regulate electric motor speed. Compressor output changes according to the current compressed air demand.

When is a VSD compressor a suitable choice?

A VSD compressor is particularly suitable for applications with fluctuating demand, where different machines switch on and off throughout the working day. For constant air demand, the selection should be made after comparison with a fixed-speed compressor.

What is the power range of the APM series?

The series includes models with power ratings from 7.5 to 75 kW, corresponding approximately to 10–100 HP.

What is the maximum air delivery of the series?

The maximum stated free air delivery is 12.2 m³/min for the SCR100APM model in its 7 bar configuration.

Are all models available for 16 bar working pressure?

No. High-pressure configurations are available only for selected models. The technical specifications of the individual compressor should be checked before selection.

Is an air receiver required?

In many installations, an air receiver helps cover short-term demand peaks, stabilise system pressure and reduce rapid changes in air consumption. The required receiver volume depends on compressor capacity and the operating profile of the system.