After the pump motor is driven by variable frequency, is there no such thing as **secondary energy efficiency** for the motor anymore?

It’s a really insightful article; I’d like to learn more about it too

After variable frequency conversion of the pump motor, its energy efficiency rating changes, but the concept of **secondary energy efficiency no longer exists. For the evaluation of motor energy efficiency, **there is a clear standard system. Traditional fixed-frequency motors have corresponding energy efficiency classification levels, such as **Level 2 energy efficiency**. When the motor operates at variable frequency, its energy efficiency differs from that in the fixed-frequency mode; evaluation is usually carried out by taking into account factors such as the energy-saving effects resulting from variable-frequency control and the efficiency of the motor under different operating conditions. But this does not mean that motors cannot be evaluated using the concept of **secondary energy efficiency after frequency conversion. In some cases, specific testing and evaluation methods can be used to compare the energy efficiency standards of variable-frequency motors with those of fixed-frequency motors, in order to determine which energy efficiency category they roughly correspond to under equivalent operating conditions. Therefore, it is not necessary to choose only one of the two options; instead, the energy efficiency level of variable-frequency motors needs to be determined based on specific application scenarios, testing methods, and evaluation criteria. At the same time, the energy efficiency standards for fixed-frequency motors can also be used as a reference for comparative analysis, in order to better understand the energy-saving performance of these motors.

This post was last edited by In silence on 2024-9-2 at 11:39. Indeed, there is no energy efficiency rating for purchasing purposes, as no corresponding standards exist; however, an energy efficiency rating does exist for the use of the product. The reason is that GB18163 and GB30254 do not provide any specifications for variable-frequency speed control motors. In other words, **the industry is not yet ready to assign energy efficiency labels to variable-frequency motors. Documents from the Ministry of Industry and Information Technology, as well as industry standards, all mention variable-frequency motors with level 2 energy efficiency. Once the conditions permit, energy efficiency labels will be introduced.

I think it’s because variable-frequency motors experience large fluctuations in efficiency at different input frequencies. There are significant differences among products from different manufacturers, and even among products from the same manufacturer. Which aspect of efficiency are you evaluating? It’s difficult to unify.