Is there a difference between fixed frequency and non-fixed frequency of screw units?

There are differences between fixed frequency and non-fixed frequency (converter). There are significant differences in the working principle, operation mode, energy consumption, stability, noise and vibration, cost, and applicable scenarios.

1. Working principle and operation mode

• Fixed frequency screw unit:

  • Working principle: Gas compression is achieved through the rotational movement of a pair of spiral-shaped yin and yang rotors that engage each other in the cylinder.
  • Operation mode: The motor’s running speed is fixed and cannot be adjusted according to actual needs. Regardless of how the air demand changes, the motor speed remains the same.

• Frequency converter screw unit:

  • Working principle: Also based on the screw compression principle, but precise control of the motor speed is achieved through advanced frequency conversion technology.
  • Operation mode: Can dynamically adjust the motor speed according to actual air demand. When the air demand increases, the motor speed increases accordingly; when the air demand decreases, the motor speed decreases.

2. Energy consumption and energy saving

• Fixed frequency screw unit:

  • Energy consumption: Because the motor speed cannot be adjusted, when the air demand is low, the unit still operates at full power, resulting in waste of energy.
  • Energy-saving: relatively low, not suitable for occasions with high requirements for energy-saving.

• Frequency converter screw unit:

  • Energy consumption: By dynamically adjusting the motor speed, it can achieve efficient and energy saving under different load conditions.
  • Energy-saving: significantly better than fixed frequency units. Depending on actual use, the energy-saving effect of the variable frequency screw unit can reach 15% or even higher.

3. Stability and output quality

• Fixed frequency screw unit:

  • Stability: The output pressure and flow rate are relatively stable, suitable for occasions where the air demand does not change much.
  • Output quality: performs well under stable load.

• Frequency converter screw unit:

  • Stability: Able to adjust the speed in real time, operate under different loads, providing more stable output pressure and flow.
  • Output quality: higher, meeting the conditions where there are high requirements for compressed air quality.

IV. Noise and vibration

• Fixed frequency screw unit:

  • Noise and vibration: Due to the fixed motor speed, greater noise and vibration may be generated.

• ChangeFrequency screw unit:

  • Noise and vibration: Run more smoothly, with less noise and vibration, providing a better working environment.

5. Cost and maintenance

• Fixed frequency screw unit:

  • Cost: The manufacturing cost is relatively low, the structure is simple, and it is easy to maintain and repair.
  • Maintenance: Regular maintenance of lubricant and filter elements can ensure normal operation.

• Frequency converter screw unit:

  • Cost: The manufacturing cost is relatively high, but due to its energy saving and stability, it can save a lot of energy expenditure and maintenance costs in the long run.
  • Maintenance: The structure is relatively complex, but it is usually equipped with advanced intelligent control systems and fault diagnosis functions, which can promptly detect and solve problems. The operation is smoother, reducing mechanical wear and failure rates, so maintenance costs are relatively low.

6. Applicable scenarios

• Fixed frequency screw unit:

  • Applicable scenarios: suitable for occasions where air demand is relatively stable, energy-saving requirements are not high, and budget is limited. For example, some small factories, workshops, or specific process links.

• Frequency converter screw unit:

  • Applicable scenarios: suitable for occasions where air demand fluctuates greatly, high energy saving requirements, and high requirements for equipment performance. For example, large factories, production lines, central air conditioning systems, and industrial applications that require continuous and stable gas supply.

7. Summary

The fixed frequency screw unit and the variable frequency screw unit have their own advantages and disadvantages. Which type of unit is selected should be evaluated based on specific application needs and economic factors. In situations where the airflow demand is relatively stable and the budget is limited, a fixed frequency screw unit is the appropriate choice; while in situations where the airflow demand fluctuates greatly and requires high energy saving and equipment performance, a variable frequency screw unit has more advantages.