@Air Compressor
2025-04-11

How to judge whether a scroll compressor is frequency converted

To determine whether a scroll compressor is a frequency conversion model, it can be comprehensively identified through the following five dimensions:

1. Equipment identification observation

  1. Nameplate marking
    Inverter models are usually clearly marked:
    • “Inverter”
    • “Variable Frequency”
    • “Frequency conversion drive”
    • example: The nameplate of Mitsubishi compressors is marked with “FV Series”, which represents the inverter model.
  2. Technical Manual Parameters
    Review technical documentation for:
    • Frequency range (e.g. 30-90Hz)
    • Frequency conversion control methods (such as vector control/V/F control)

2. Control system testing

  1. Existence of frequency converters
    • Inverter compressors must be equipped with independent frequency converters (usually located in the electric cabinet)
    • appearance characteristics: The inverter has a cooling fan, digital display, and frequency adjustment knob
  2. control interface
    • Inverter models provide:
      • 0- 10V analog input (for central control)
      • Modbus/CAN communication interface
      • Frequency setting terminal

3. Analysis of operating characteristics

  1. start-up characteristics
    • Soft start of inverter compressor (current rises slowly)
    • The starting current of the fixed frequency compressor is 5-7 times the rated current
  2. noise change
    • Inverter models reduce the noise by 3-5dB(A) at 50% load compared to full load
    • The noise of fixed frequency models is basically constant

4. Comparison of energy efficiency ratios

load rate Inverter model EER Fixed frequency model EER
100% 3.2-3.5 3.0-3.3
70% 3.0-3.3 2.5-2.8
50% 2.8-3.0 2.0-2.3

V. Professional Detection Tools

  1. clamp ammeter
    • Measuring operating current: Inverter models reduce the current significantly under partial loads
    • example: The full load current of the 11kW compressor is 22A, the current of the inverter model is about 12A at 50% load, and the fixed frequency model still remains at 20A.
  2. spectrum analyzer
    • Test the vibration frequency of the motor: There is a deviation between the frequency of the inverter model and the power frequency (50Hz)
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