IE Efficiency Classes Explained
The IE classification system was introduced by IEC 60034-30-1 (2014) to provide a globally harmonised framework for motor efficiency ratings. Efficiency is measured at full load, rated voltage, and rated frequency using standard test methods.
| IE Class | Name | Status |
|---|---|---|
| IE1 | Standard efficiency | Banned for new motors >0.75 kW in EU since 2021 |
| IE2 | High efficiency | Mandatory for 0.12–0.75 kW in EU; permitted above 0.75 kW only with VFD |
| IE3 | Premium efficiency | Mandatory for 0.75–1,000 kW in EU since July 2021 |
| IE4 | Super premium efficiency | Voluntary; typically PM or SynRM motors |
| IE5 | Ultra premium efficiency | Emerging; defined in IEC 60034-30-2 for variable speed drives |
Efficiency Values by Power Rating (4-pole, 50 Hz)
| Rated power (kW) | IE1 (%) | IE2 (%) | IE3 (%) | IE4 (%) |
|---|---|---|---|---|
| 0.75 | 77.4 | 80.7 | 82.5 | 85.7 |
| 1.5 | 81.0 | 84.1 | 87.4 | 89.5 |
| 4 | 84.3 | 87.4 | 89.8 | 91.8 |
| 7.5 | 87.1 | 89.8 | 91.7 | 93.3 |
| 15 | 89.1 | 91.4 | 93.0 | 94.4 |
| 37 | 91.7 | 93.3 | 94.5 | 95.7 |
| 75 | 93.0 | 94.3 | 95.4 | 96.4 |
| 200 | 94.2 | 95.4 | 96.2 | 97.0 |
Energy Savings from Upgrading
Annual energy saving from upgrading IE1 to IE3 at rated load:
Prated = rated output power (kW), h = annual operating hours
Example: 7.5 kW motor, 6,000 h/year, £0.15/kWh
- IE1 losses = 7.5 × (1/0.871 − 1) × 6,000 = 7.5 × 0.1481 × 6,000 = 648 kWh losses
- IE3 losses = 7.5 × (1/0.917 − 1) × 6,000 = 7.5 × 0.0905 × 6,000 = 407 kWh losses
- Annual saving = 241 kWh × £0.15 = £36/year per motor
For a plant with 50 × 7.5 kW motors, total saving = £1,800/year. Motor premium over IE1: ~£100–200 per motor. Payback: 2.8–5.6 years — often justified by regulatory compliance alone.
EU Regulations Timeline
- June 2011: IE2 mandatory for 0.75–375 kW motors (EU Regulation 640/2009)
- January 2015: IE3 (or IE2 with VFD) for 7.5–375 kW
- July 2021: IE3 mandatory for 0.75–1,000 kW (EU Regulation 2019/1781); IE2 for 0.12–0.75 kW; IE2 for 2-pole 1–1,000 kW, 4-pole and 6-pole 1–1,000 kW motors for some hazardous-area motors
Exemptions apply to motors for explosive atmospheres (ATEX), submersible pumps, crane-duty motors, and some high-slip designs. Check the full regulation for your specific motor application.
Reading the Efficiency on the Motor Nameplate
IE3 motors carry the IE3 symbol on the nameplate. The efficiency value (ηN) at rated load, rated voltage, and rated frequency is also stated. When purchasing, verify both the IE class symbol and the numeric efficiency value — both must match the IEC 60034-30-1 minimum values for the rated power and number of poles.