What is the rated frequency of the screw blower?

Basic Standard for the Rated Frequency of Screw Fans

The rated frequency of a screw blower primarily depends on the design standards of its accompanying motor and the grid regulations of the intended operating region. Globally, the rated frequencies of industrial AC motors are generally governed by two main standards:50Hzand60Hz.

• 50Hz Standard: In China, Europe, Oceania, and most of Asia, the standard grid frequency is 50Hz Therefore, standard screw-type fans sold and used in these regions typically have motors rated at a frequency of 50Hz.
• 60Hz Standard: In North America, certain countries in South America, as well as regions such as Japan and South Korea, the standard grid frequency is 60Hz For screw blowers intended for these markets, the rated frequency is designed to be 60Hz.

The Influence of Rated Frequency on Fan Operating Parameters

The rated frequency directly determines the motor’s synchronous speed under rated operating conditions, thereby influencing the core performance parameters of the screw blower:

• Rotational Speed and Airflow: Under the same number of motor poles, 60Hz The motor’s rated speed is higher than 50Hz Motor. Therefore, the same physically structured screw blower unit, in… 60Hz The displacement and air volume at the rated frequency are typically greater than 50Hz Operating conditions.
• Shaft Power and Energy Consumption: As engine speed and displacement increase, 60Hz Under operating conditions, the shaft power required by the fan will also increase accordingly. When selecting a motor, it is essential to ensure that its rated power can adequately meet the load requirements at the corresponding frequency.

Distinction between Variable-Frequency Control and Rated Frequency

In practical industrial applications, many screw blower systems are equipped with variable-frequency drives to achieve energy savings and flow regulation. In such cases, it is essential to distinguish between “rated frequency” and “operating frequency”:

• Rated frequency: is the reference design frequency indicated on the motor nameplate (e.g., 50Hz), at this frequency, the motor delivers its rated power and rated torque.
• Operating frequency: This is the actual output frequency of the inverter. Through variable-frequency control, the screw blower’s operating frequency can be adjusted below its base frequency (rated frequency), thereby changing the rotational speed and airflow rate to achieve on-demand air supply.

It should be noted that when the operating frequency is below the rated frequency, the motor typically operates in the constant-torque region; when it exceeds the rated frequency, it enters the constant-power region, where airflow increases but pressure may be limited.

Recommendations for Equipment Selection and Parameter Verification

When purchasing and installing screw blowers, accurately verifying the rated frequency is essential to ensuring the equipment’s safe and stable operation.

• Verify the on-site power grid.: It must be ensured that the rated frequency indicated on the fan’s nameplate exactly matches the actual frequency of the local power grid. If… 50Hz Wind turbine connection 60Hz In the power grid, this can cause the motor speed to increase, the current to rise, and even lead to overload and burnout; conversely, it may result in insufficient airflow and reduced motor output.
• Check the motor nameplate.The rated frequency of a screw-type blower is directly indicated on the drive motor’s nameplate. During equipment acceptance upon arrival, particular attention should be paid to verifying key parameters on the nameplate, such as frequency, voltage, and power.Fan parameters.