Subsynchronous SER Drive

Subsynchronous SER Drive being assembled in factory.

Subsynchronous Recovery Drives (SRD) is a simpler and cost-effective solution that is used widely in Wound Round Induction Motors (WRIM) applications. These type of drives are capable of starting the motor from standstill and are used for smaller quadratic load applications such as fans or pumps. 

Subsynchronous SER Drives offers the best value solution for applications using slip ring motors (WRIM) allowing users to upgrade their existing mill without replacing their existing motors. Integrating the SER drive also provides significant cost saving for electricity consumption with a very high return-of-investment (ROI) - typically a payback period shorter than 1 year. Detailed calculation of process improvement can be provided during the study phase.


Background of our Technology Partner

Our SER drives are manufactured by ElectroDrives, who is one of our trusted technology partners.

Electrodrives is based in Madrid-Getafe, Spain and is a global market leader in Slip Energy Recovery (SER) Drives for Slip Ring Motors that are mainly used in the mining industry especially for SAG Mills. Following the acquisition of International Electronics S.A. (IES) in 2018, ED is focused to further innovate and continue developing customer-focused solutions for the mining industry.

Technical Specifications : Subsynchronous SER Drive


Typical Applications:

Motor Rated Power:

Typical Speed Ranges

(% of Synchronous Speed)

Typical Grid Voltages:

Motor Rotor Voltage:

Input Power Factor:


Starting Method:


Operating Temperature:

Cooling Method:

Switching Semiconductor:

Plant Communications:

Single Drive

Quadratic Load (Fans, Pumps, Blowers, Compressors)

500 kW up to 7,000 kW (per motor)

0% - 100% (Default for starting)

70% - 100% (Typical without starting)

60% - 100% (Extended range of motor synchronous speed)

3.3kV, 4.16kV, 6.0kV, 6.6kV, 11kV, 13.8kV

Up to 4,200V

0.85 (typical)

>99.3% ( For motors of 5,000kW and above)

Starting capability included (0-100% speed range) or External LRS/RCS

Bump-less bidirectional transfer to LRS/RCS

+0 .. +50 deg C

Air-cooled (No water or other fluids)

IGCTs rated 4,500V

Ethernet/IP, Modbus-TCP, Profibus, Profinet, Ethercat, Devicenet