How to Select the Frequency Converter?

Select the type of frequency converter according to the type of production machinery, speed regulation range, static speed accuracy, starting torque requirements, determine which control mode frequency converter is most suitable. The so-called suitable is not only easy to use, but also economical, in order to meet the basic conditions and requirements of the process and production.

Frequency Converter

The Motor to be Controlled and the Converter Itself

1) The number of poles of the motor. Generally, the number of poles of the motor should not be more than (extremely suitable, otherwise the capacity of the inverter must be appropriately increased.

2) Torque characteristics, critical torque, acceleration torque. In the case of the same motor power, relative to the high overload torque mode, the inverter specifications can be selected by derating. 3) Electromagnetic compatibility. In order to reduce the interference of the main power supply, a reactor can be added to the intermediate circuit or the input circuit of the inverter, or a front isolation transformer can be installed. Generally, when the distance between the motor and the inverter exceeds 50m, reactors, filters, or shielded protective cables should be connected in series between them.

Selection of Converter Power

The efficiency of the system is equal to the product of the efficiency of the frequency converter and the efficiency of the motor, and the system efficiency is higher only when both work at higher efficiency. From the perspective of efficiency, when selecting inverter power, pay attention to the following points:

1) It is most suitable when the power value of the inverter is equal to the power value of the motor, so that the inverter can run at a high efficiency value. To

2) When the power classification of the frequency converter is different from the power classification of the motor, the power of the frequency converter should be as close as possible to the power of the motor, but should be slightly larger than the power of the motor. To

3) When the motor is frequently started, braked, or under heavy load starting and working more frequently, a higher-level frequency converter can be selected to use the frequency converter for long-term and safe operation.

4) After testing, the actual power of the motor is indeed surplus. You can consider using a frequency converter with a power lower than the power of the motor, but pay attention to whether the instantaneous peak current will cause overcurrent protection. To

5) When the power of the inverter and the motor are not the same, the settings of the energy saving program must be adjusted accordingly in order to achieve a higher energy saving effect.

Selection of the Box Structure of the Frequency Converter

The cabinet structure of the inverter must be adapted to the environmental conditions, that is, factors such as temperature, humidity, dust, pH, and corrosive gases must be considered. The following structure types are commonly available for users to choose from:

1) The open type IPOO type has no chassis itself, and is suitable for installation in the electric control box or on the screen, panel, and rack in the electric room, especially when multiple inverters are used in a centralized manner. This type is better to choose, but the environmental conditions are more demanding.

2) The enclosed IP20 type is suitable for general use, where there may be a small amount of dust or a small amount of temperature and humidity;

3) The sealed IP45 type is suitable for environments with poor industrial site conditions;

4) The sealed IP65 type is suitable for occasions with poor environmental conditions, water, dust and certain corrosive gases.