International Electrotechnical Commission ( IEC ) and national standards GB 18613 Energy efficiency levels are all classified based on the motor's efficiency rating. The motor's efficiency ( Efficiency ) is a core metric for measuring its energy conversion capability. It reflects the motor’s efficiency in converting electrical energy into useful mechanical energy; the lower the losses, the higher the efficiency.

 

I. The Defining Formula for Efficiency

η = Pout/Pin × 100%

-eta Motor efficiency (unit: % )   

- Pout Output mechanical power (useful power at the shaft end, unit: W or kW )   

- P in Input power (the total active power absorbed by the motor from the power supply, unit: ) W or kW )   

Key point: The input power must be the input active power (not the apparent power!), and the output power is mechanical power, which needs to be calculated using torque and rotational speed (formula: Pout = τ × ω ， tau For torque [N·m] ， omega For angular velocity [radians per second] ).

 

II. Sources of Energy Loss (Why Efficiency) < 100% )

During operation, motors primarily generate four major types of losses, resulting in some electrical energy failing to be converted into mechanical energy:   

1. Copper loss (winding loss): Current flows through the stator. / The rotor winding resistance generates heat, which increases significantly as the load current rises.                           2. Iron loss (core loss): Eddy current loss in the core caused by an alternating magnetic field. + Hysteresis loss, voltage / Increases as frequency rises.                       3. Mechanical losses: bearing friction, wind resistance (from cooling fans)—the higher the rotational speed, the greater the losses.                                                    

4. Stray Losses: Additional heating caused by leakage flux, air-gap harmonics, and other factors.                                               

III. The Engineering Significance of Efficiency

- Energy efficiency: The higher the efficiency, the less power consumed for the same output (e.g.: η=90% the motor than η = 80% Energy savings approximately 10% ).   

- Operating costs: Although high-efficiency motors have a higher initial purchase price, their long-term electricity costs are lower (suitable for industrial applications involving continuous operation).   

- Temperature Rise and Lifespan: When losses are converted into heat, high-efficiency motors experience lower temperature rises, slower insulation aging, and longer lifespans.   

- Environmental requirements: International standards (such as IE3、IE4 ) Mandate the improvement of motor efficiency to reduce carbon emissions.

 

IV. National Standards and International Standards (with IEC 60034-30-1 For example) Comparison

International Electrotechnical Commission ( IEC ) promulgated by IE Energy efficiency rating, since 2008 Since its introduction, it has become a globally widely adopted standard for motor energy efficiency. This standard further subdivides motor energy efficiency into: IE1 To IE5 Five levels, of which IE1 Represents the lowest energy efficiency, while... IE5 This signifies the highest energy efficiency. The classification into these levels is based on the motor’s efficiency rating: the higher the efficiency rating, the lower the motor’s energy consumption, and consequently, the better the energy-saving effect.

China's Motor Energy Efficiency Standards GB 18613 “Energy Efficiency Limit Values and Energy Efficiency Grades for Electric Motors” is a mandatory national standard. It has been issued in successive versions. 2006 Edition, 2012 Edition and 2020 Three versions, 2020 Version standard for 2020 Year 5 Moon 26 Released daily, and in 2021 Year 6 Moon 1 It will officially take effect starting today. It applies to rated voltages in... 1000V The following, 50Hz Supplied by a three-phase AC power source, with a rated power range of: 120W To 1000kW three-phase asynchronous motors, single-phase asynchronous motors, and motors used in air conditioner fans. The energy efficiency levels specified in this standard are categorized as: 3 level, and from the date of implementation of the standard, the energy efficiency standards for motors must be met. 3 Level or above.

 

GB 18613 - 2020 To put IE5 Efficiency is rated as the highest energy efficiency class for China's three-phase asynchronous motors. IE4 The efficiency rating is Level 2 energy efficiency. IE3 The efficiency rating is Level 3 energy efficiency. From the date of implementation of the standard, IE3 Efficiency has become the minimum energy efficiency limit (Level 3) for China’s three-phase asynchronous motors. Three-phase asynchronous motors falling below this energy efficiency limit are prohibited from being manufactured and sold.

Some people also believe that the Level 3 efficiency rating in the 2020 standard corresponds to IE2. To verify this, the editor has conducted a thorough investigation and can confirm that the Level 3 efficiency rating in the 2020 standard actually corresponds to IE3. The screenshot below shows that the values within the red boxes are identical. If you spot any inaccuracies, please feel free to point them out.

National standard:  

IEC Standard:

 

V. Recommendations:   

1. Made in the Chinese market / To sell motors, the following must be met: GB 18613-2020 Energy efficiency 3 Level ( IE3 );   

2. Exporting enterprises must simultaneously meet the standards of the target country (e.g., the European Union). EU 2019/1781 );   

3. High-end projects should prioritize energy-efficient options. 2 Level ( IE4 ) The motor is designed to reduce long-term energy consumption.   

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