Comparison of Power Frequency and Frequency Conversion Power Saving of Screw Air Compressor and Selection Suggestions
in the selection process of screw air compressor, the power saving of power frequency and frequency conversion equipment is the focus of user’s attention. The following professional analysis is carried out from four aspects: working principle, energy efficiency difference, applicable scenario and selection suggestion:
1. working principle difference
-
power frequency air compressor
the power frequency equipment runs at a constant speed, and the output pressure is adjusted by loading and unloading. The starting method is usually star-triangle starting, and the starting current is large (about 5-8 times of the rated current), which has a large impact on the power grid and equipment. In the unloading state, the motor still runs at no-load speed, and the energy consumption is high. -
Variable frequency air compressor
the frequency conversion equipment adjusts the motor speed through the frequency converter to achieve on-demand air supply. The starting current is low (about 1.2 times of the rated current), and the impact on the power grid and equipment is small. At low load, the inverter can reduce the motor speed and reduce energy waste.
2. energy efficiency difference comparison
| characteristics | power frequency air compressor | variable frequency air compressor |
|---|---|---|
| energy consumption regulation | running at constant speed, the output power cannot be adjusted according to the load, and the energy consumption is high when unloading (about 20% of full load -40%). | Adjust the motor speed according to the actual gas consumption to achieve accurate gas supply and extremely low energy consumption during unloading. |
| energy saving effect | the efficiency is higher under constant load, but the energy consumption increases significantly when the load fluctuates. | In the scene of large load fluctuation, the energy saving effect is remarkable, and 20%-40% of electric energy can be saved in practical application. |
| Starting shock | the starting current is large, which has a large impact on the power grid and equipment. | The starting current is small, the soft start is realized, and the impact on the power grid and equipment is small. |
| Operating noise | the operating noise is high and fluctuates with the speed change. | Under most operating conditions, the operating speed is lower than the rated value, and the noise and wear are significantly reduced. |
3. applicable scenario analysis
- applicable scene of power frequency air compressor
- constant load: If the gas consumption is stable and close to the rated capacity of the equipment, the power frequency machine can maintain efficient operation and reduce the energy consumption difference with the frequency converter.
- Short or intermittent use: For scenarios with short running time and small gas consumption, the power frequency machine may be more economical due to no inverter loss.
- Cost-sensitive selection: The initial purchase cost is lower than that of the inverter, which is suitable for users with limited budget and low energy saving requirements.
- Variable frequency air compressor applicable scene
- large load fluctuation: If the gas consumption fluctuates with the production rhythm, the frequency converter can quickly adjust the output to avoid energy waste.
- long-term stable operation: In scenarios where continuous gas supply is required, the frequency converter can maintain efficient operation and reduce overall energy consumption.
- High requirements for air pressure stability: The frequency converter can realize precise pressure control to meet the needs of precision manufacturing, food processing and other industries.
4. selection recommendations
- preferential selection of variable frequency air compressor
- if the gas consumption fluctuates greatly, the running time is long or the energy saving requirement is high, the frequency converter is the better choice. Its energy saving effect is remarkable, and can extend the service life of equipment.
- Applicable scene of power frequency air compressor
- in constant load, short-term use or cost-sensitive projects, power frequency machines may be considered. However, it should be noted that its energy consumption may be higher than that of the frequency converter under long-term operation.
- Comprehensive assessment
- decisions need to be made in conjunction with the full life cycle cost of the equipment (including energy consumption, maintenance, life, etc.). Although the initial purchase cost of the frequency converter is high, it can save a lot of electricity bills under long-term operation, and the comprehensive economic benefits are significant.
Conclusion:
the variable frequency air compressor is more energy-saving in most scenarios, especially suitable for large fluctuations in gas consumption or long-term stable operation. Power frequency machines are suitable for specific scenarios, such as constant load or short-term use. In the selection, it is recommended that users comprehensively evaluate energy consumption, cost, maintenance and other factors, and choose the equipment that best meets the actual needs.
