Is it better to choose power frequency or frequency conversion for low-power screw air compressors

Technical description on selection of small power screw air compressor

In industrial production, the selection of low-power screw air compressors needs to be comprehensively judged based on equipment characteristics, use scenarios and long-term cost-effectiveness. The following provides you with a detailed analysis of the differences and applicability of power frequency and frequency conversion drive methods from the perspective of technical principles and industry practice.

1. Comparison of core driving principles

1. Power frequency air compressor
   • The power supply is supplied at a fixed frequency (50 Hz), the motor runs at a constant speed, and the exhaust volume is adjusted through a mechanical valve.
   • When starting, the star triangle starting method is adopted, and the current impulse can reach 6 times the rated value, which has a significant impact on the power grid load.
   • When the load fluctuates, it is necessary to adapt to the demand through frequent start-ups and stops or no-load operation, resulting in obvious waste of energy consumption.
2. variable frequency air compressor
   • The power supply frequency is changed by the frequency converter to achieve stepless adjustment of the motor speed, thereby accurately matching the gas demand.
   • Using soft start technology, the current rises gently (≤ 1.2 times the rated value), with little impact on the power grid.
   • During operation, the speed is adjusted in real time according to feedback from the pressure sensor to ensure stable air supply pressure and avoid no-load loss.

2. Analysis of applicable scenarios

1. Application scenarios for power frequency models
   • Stable air consumption: Scenes with small load fluctuations such as small processing workshops and laboratories.
   • cost sensitive: Users with limited initial procurement budget and able to accept certain energy consumption waste.
   • simple working conditions: Application scenarios with low requirements for the stability of supply pressure.
2. Application scenarios for inverter models
   • Gas consumption fluctuates greatly: Scenarios such as food packaging and electronics manufacturing that require frequent adjustment of gas supply.
   • High energy efficiency requirements: Users who pursue long-term operating cost savings or need to cope with differences in peak and valley electricity prices.
   • Strict process requirements: Scenarios where gas supply pressure needs to be stabilized to improve production efficiency and product quality.

3. Long-term cost-benefit assessment

1. Initial purchase cost
   • Due to its simple technology, power frequency models usually have low procurement costs.
   • Frequency conversion models require a high initial investment due to the need to be equipped with frequency converters and control systems.
2. Long-term usage costs
   • Energy consumption comparison: When power frequency models are running under part load, the no-load loss can reach 40%; frequency conversion models use frequency down-conversion technology to reduce the no-load power consumption to below 15%, and the overall energy saving reaches more than 20%.
   • maintenance costs: Due to stable operation and small mechanical wear, the maintenance cycle can be extended by more than 30%; frequent start and stop of power frequency models may easily lead to aging of parts and high maintenance costs.
   • equipment life: Frequency conversion models can extend the service life of equipment through soft starting and smooth operation; power frequency models have a high mechanical impact, and equipment depreciation rate is faster.

4. Comprehensive selection suggestions

1. Scenarios where frequency conversion models are preferred
   • Scenes where gas consumption fluctuates more than ±30%.
   • Industries that require 24-hour continuous operation and are sensitive to energy efficiency.
   • Scenarios that need to be connected to an intelligent management system for remote monitoring.
2. Scenario for power frequency models can be considered
   • Scenes with stable gas consumption and average daily running time ≤8 hours.
   • The initial budget is strictly limited and users who can accept higher energy costs.
   • The power grid capacity is insufficient to support the start-up requirements of inverter models.

conclusion
The selection of low-power screw air compressors needs to balance initial investment and long-term benefits. For scenarios with large fluctuations in gas consumption, high energy efficiency requirements, or stable gas supply is required, although the initial cost of the inverter model is higher, the overall cost-effectiveness is better by saving energy and extending equipment life; for scenarios with stable gas consumption and small load fluctuations, power frequency models can meet basic needs. Enterprises can choose the most suitable driving plan based on actual working conditions, energy consumption targets and budget conditions.