Drives, (variable speed inverter drives) have not had a similar IE classification as motors. The recently published EN 50598-2 standard addresses this and introduces two new energy efficiency indicators: an IE class for the drive; or “complete drive module” (CDM) as defined in the standard.

EN 50598-2 will help OEMs and users get better operational efficiencies in complete systems, resulting in energy savings and improved ROI of the entire operation. It defines energy efficiency indicators (“IE” and “IES”) for the complete drive module (CDM) and the combination of the CDM and motor to form a “power drive system” or PDS. The standard includes methodology to determine the CDM and PDS losses, assigning the IE and IES values.

New IE classification

The first new classification for a variable speed drive is IE, which the standard calls a “complete drive module,” or CDM. The CDM consists of the drive and any of the other auxiliary equipment connected to the drive, like a braking chopper or EMC filter. The IE classification is like what motors have had, ranging from IE0 to IE4. The lower the IE number, the less efficient the CDM.

New  IES classification

The second new classification is an IES system classification for the “power drive system” or PDS, which is the combination of the motor and the drive together. This is new, and is valuable because in addition to the overall efficiency classification, regulators provide in the EN 50598-2 standard a defined set of operating points at which the efficiency of the power drive system is measured.

Engineers realise, many motors don’t need to be run at full speed all the time, they typically run at partial loads, so these measurements at defined operating points provide that partial load efficiency values. Users can estimate energy use for your process or machine based on their typical operating profiles.

IES classes are defined from IES0, the lowest efficiency, to IES2, the current label for the highest-efficiency class. More IES classes will be defined in the future. These new classifications are valid for motor and drives that are within the 100 to 1,000 volts, with a power up to 1,000 kW.

The IE classification for drives, the CDMs is done differently than for motors. For motors, the IE classification is taken at 100 percent motor speed and 100 percent motor torque. For the CDM, the classification is taken at 90 percent frequency and 100 percent current. As such, you can’t add a motor IE classification and a CDM classification to get the PDS IES value.

To learn more about the new standard, the new IE and IES classifications and how they might affect you visit ABB’s EcoDesign website