Execution of the RotorProtek project

ELECTRO DRIVES, S.L. announces the successful conclusion of the RotorProtek project, a technology aimed at the protection and monitoring of the starting control of wound rotor motors. This initiative found financial support by the Center for Industrial Technological Development (CDTI) and co-financed by the European Regional Development Funds (ERDF).

The project addresses a specific market need by developing a functional electronic controller prototype designed to be installed in liquid resistance starters for motor starting. This device incorporates several functionalities in a single electronic unit that acts on the starting process of wound rotor motors. The main functionalities are:

  1. Current, torque, and speed transducer

  2. Motor rotor protection

  3. Starts and events logger and analysis

  4. Conditioning monitoring

  5. Closed-loop speed/torque control

  6. Liquid rheostat protection

  7. Grinding mill protection, including frozen charge protection

Wound rotor induction motors play a crucial role in a wide variety of industries such as mining, cement, and metallurgy. These motors are used in key operations such as ore grinding using semi-autogenous or ball mills, driving fans, or powering rolling mills, among other applications that have a direct impact on production in these industries.

Typically, these motors are accompanied by auxiliary equipment designed to optimize their performance. These include liquid resistance starters, which are connected to the motor rotor to provide a higher initial resistance during startup, increasing torque, and reducing current demand during this process. In specific applications, variable speed drives are used, such as SER drives, which are capable of controlling speed beyond the motor rated speed, returning the slip energy to the grid.

Effective monitoring systems and proper maintenance are crucial for optimizing processes and avoid unnecessary shutdowns. In this context, RotorProtek plays a key role by providing valuable information that enables industries to anticipate critical equipment failures and plan preventive maintenance. Additionally, it offers active motor protection through adjustable faults and alarms to best suit each application.

To achieve this, RotorProtek will be installed in liquid resistance starters, where rotor cables are accessible, alongside one or two current transducers to measure rotor currents. Through these currents, RotorProtek calculates various parameters, such as stator currents, motor developed torque, speed, acceleration, resistant torque, system inertia, and rheostat resistance ratio, among others. This provides the plant process control a complete view of what is happening in the system.

The collected information will be accessible on any mobile device by connecting to RotorProtek’s on-board Wi-Fi network, allowing access to its web page. From there, users can enter administrator mode to customize system parameters, configure alarms, and manage faults. Additionally, RotorProtek can transmit this information to the plant control through standard communication protocols such as Modbus TCP, Ethernet IP, or Profinet, if desired.


The main goal of the RotorProtek project is to incorporate an innovative solution capable of improving the performance and extending the lifespan of high-power motors used in the grinding processes of the mining, cement, and metallurgical industries. Through the design, development, and testing of various electronic controller prototypes with interconnection capabilities, the project aims to integrate functionalities such as (i) main motor protection, as well as its additional starting and speed control equipment, (ii) optimization of startup energy consumption by controlling the movement of liquid rheostat electrodes, and (iii) speed and torque transducer incorporating data monitoring and acquisition capabilities to help monitor the operation of the motor and liquid rheostat.

This project has had a duration of 17 months with a budget of EUR 498,809.

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