The WEG drive system, consisting of 5000KW 4160V 8-pole W60 induction motors, MVW01 medium voltage drives with input panel, control a semi-autogenous mill (SAG) at the Meliadine mine in the Nunavut territory, Northern Canada.

The SAG mill is one of the main equipment of the site, responsible for the grinding process of the extracted ore and, therefore, requires the equipment used for its propulsion and control to have very high reliability and availability.

The combination of WEG induction motor and frequency inverter deliver a simple, versatile and reliable solution to the customer, reducing maintenance needs and downtime, as well as the implementation of various protections and overall process optimization.

The frequency inverter ensures smooth operation without mechanical stress or impacts on the grid during startup and operation. Through its speed control, the inverter enables the mill to operate at the optimum operating point of the system, providing higher grinding quality and offering significant energy savings.

The WEG MVW01 medium voltage frequency inverter, selected for its modern and simplified construction, thanks to the use of medium voltage power components and WEG's 30 years of experience working with frequency inverters, also has specific functions that have improved the process and avoid common problems in this type of application such as:

  • Frozen Charge function (detection & release): prevents damage to the mill structure due to the possibility of material sticking to the mill structure wall at the time of start-up;

  • Positioning Function: Fast and automatic positioning of the mill based on angle or linear reference, and allows creeping at low speeds to facilitate component maintenance and replacement.

  • Roll Back Function: The inverter automatically controls the mill's return smoothly to the rest position where speed and torque are zero and with the mill balanced.

In addition to the proven technical expertise for this type of application, WEG has also shown the ability to meet customer agreed delivery times, another critical point in this supply due to the weather conditions in this region. In winter, the local temperature can reach -48°C and, due to the polar climate, transportation by ship to the site is only possible during few weeks of the year.

Due to the low temperature, the storage, installation and commissioning of equipment were also a challenge apart. WEG has the important advantage of being able to perform all the necessary tests for the complete system in Jaraguá do Sul (SC), Brazil, the main manufacturing site of its medium voltage equipment. These tests, which can be performed in different laboratories up to 20 MVA, require all the equipment to be previously interconnected, verified and placed under nominal load, allowing the identification and resolution of some difficulties normally encountered only at the time of installation on the customer’s site. As a result, the entire installation and commissioning process was completed in a very short time and quite successfully.