What is a VSD/PM screw compressor?
A screw compressor with a variable speed drive (VSD) automatically adjusts the speed of the screw compressor in function of the compressed air requirement and in real time according to the demand.
VSD/PM screw compressors are designed for activities where the demand for compressed air fluctuates, depending on what the compressed air users in the different processes need in terms of flow demand.
In contrast to compressors with a fixed speed, often V-belt driven screws, which only run at full power, the VSD/PM screw compressor offers numerous advantages:
- The VSD/PM screw compressor runs when it is needed, resulting in significantly lower energy costs, so that the extra investment in VSD/PM technology pays for itself.
- The VSD/PM screw compressor starts and stops under full system pressure, relief is no longer necessary, saving both time and energy.
- No time and especially energy is lost due to unnecessary idling.
- There is no blow-off loss during normal operation.
- Avoid fines from your energy supplier due to power peaks when (re)starting.
- The pressure in the compressed air system is more consistent but also lower because the delta can be lowered, minimizing possible compressed air leaks.
- This technology eliminates all the shortcomings of the conventional screw compressor and ensures that energy costs remain manageable.
An additional element of VSD/PM technology is that you have to be protected considerably lower, also important when using power generators, here also a much lower starting load.
Energy saving is an important element in the choice of this technology
- The largest cost component (about 70%) in the total cost of ownership of an industrial screw compressor is not the machine itself, but the energy cost.
A VSD/PM screw compressor costs significantly more than a conventional fixed speed compressor, but this extra investment is quickly recouped through the energy savings. The VSD/PM technology can reduce the energy costs of your screw compressor by a factor of up to 50%.
This depends on the application and the capacity of the compressor.
- The government and/or the electric utility may offer a rebate or tax break to encourage you as a company to switch to an energy-efficient VSD/PM technology that helps reduce power consumption and minimize sudden spikes in demand.
The operation of the VSD/PM screw compressor
- The variable drive saves energy by adjusting the speed of the compressor with a frequency control.
Unlike a conventional screw compressor, the PLC control supplies the VSD/PM screw compressor with the specific required voltage.
The system pressure and flow is measured in real time and this allows the integrated controller to adjust the motor speed and torque to the actual air requirement.
The idea is simple, but the underlying technology is highly advanced.
- The PM motor with a voltage field between 300 and 450 volts is controlled by vector control technology with ultra-fast response time.
This results in a high start-up impulse and has less effect on the wear of the moving parts.
- The insulation class IP-55 also makes these compressors ideal for use in a dusty environment (woodworking, sandblasting, breaking yards, etc.).
- The developed heat is removed centrally by a temperature-controlled and over-dimensioned air/oil cooler
- The compressor automatically follows the compressed air demand, both in pressure and flow rate, which makes it possible to work with a much smaller compressed air tank.
By fixing the working pressure at 7 bar, you also avoid useless pressure build-up in the boiler.
- The color touchscreen control panel is clear and allows easy operation as well as a schematic representation of the operation and maintenance schedule of the compressor.
As an option you have the possibility to monitor your compressor via the internet.
VSD drive
- The magic is in the drive, through the combination of motor and screw element.
The VSD technology has the best results with screw compressors, because their flow rate and energy consumption are speed related.
If the speed of the motor is adjusted, the screw element also follows this 1 to 1, resulting in an adjusted compressed air flow rate.
The IE5+ Oil-cooled PM electric motor is specifically designed for this application, in terms of cooling and efficiency across the entire speed range.
- Our latest VSD technology features an internal permanent magnet motor. (NdFeB)
In the VSD+ design, the PM motor shares the rotor shaft with the propeller element, creating a direct drive that is extremely quiet and, above all, energy efficient.
Motor and screw element form a closed oil-cooled circuit.
This is also part of the energy savings achieved.
Finally, the new technology considerably reduces the required floor space compared to the conventional screw compressor.
- A VSD compressor is by definition not designed to run continuously at full speed, even in a master/slave setup the VSD/PM compressor is the ideal technology to ensure optimum compressed air generation.
