Variable frequency drive technology is an essential component of state-of-the-art refrigeration technology. Users who are both open and interested will soon get up to speed regarding the requirements placed on the system planning and implementation.

The following essential advantages are obtained by continually adapting the power of a compressor pack by controlling the speed of a variable speed compressor:

• Improved cooling quality by maintaining a constant suction pressure
• Wider range of operation of the refrigeration power
• Increased power by increasing the speed of the variable speed compressor
• Energy saving
• Longer compressor lifetime
• Better possibilities of providing monitoring, remote setting and diagnostics

1. Effect of technical process
After the reform for fans, the damper which used to adjust the flow is fully-opened. Resistance loss is greatly reduced. In addition, as the motor operates in V/F mode in which operating frequency varies so resonance is avoided. It is unexpected that the problem of pipeline cracking is solved.

2. Impact on the grid
When motor starts in direct on line state, its starting current might be 7~8 times of rated. The peak current would increases the electric stress of the windings and leads to additional heat so that the motor's lifespan reduces. After the reform, soft-start becomes a reality by which motor current starts from zero speed/voltage (torque lifting is available) to work current. The load driven by AC drive operates in V/F control mode or vector control mode, hardly impact on the grid.

3. Maintenance
By AC drive, the motor usually runs in range of 30~40Hz. It reduces the speed of fan contrast to line frequency. In addition, soft-start could prolong the lifespan of spare parts, insulation and shaft. Moreover, it reduces the maintenance labour and cost.

4. Energy-saving of AC drive
In addition to the benefits above, what is more, the perfect energy saving effect is gained.