In the late 1970’s, Siemens partnered with Bucyrus International of Milwaukee, Wisconsin to build the first AC drive system for large electric mining shovels. In the meantime more than 100 shovels with Siemens Acutrol AC are operating in North and South America, Australia, Asia, and Europe.

In 2000 we introduced the third generation Acutrol Series III / IGBT to the market. The first BI 495BII with Acutrol III has been operating at a mine in Peru since February 2000, and is setting new standards for performance and reliability.

The overall goal that drives design and sales of shovels is to minimize the costs per ton of material moved. This goal is influenced by many factors over the useful life of the machine. The most important factors are productivity, reliability, compatibility with the mine’s power distribution system, efficiency, maintenance and ease of troubleshooting. Acutrol III / IGBT creates benefits for the customer in each of these important areas. We have taken another step towards the goal of becoming a “low cost per ton leader.”

The AC squirrel cage induction motor is fundamental in reducing cycle time and cutting maintenance costs. The absence of DC motor commutation limits enables the shovel’s motions to reach faster speeds in digging and repositioning. AC motors don’t need brushes and don’t require commutator maintenance / overhauls like DC motors.

Throughout the development reliability, MTBF, and MTTR were our utmost concern. We expect shovel drive system MTBFs in the hundreds of days from the use of medium voltage, modular IBGT inverters with high power density and fewer components, military grade controls, and a single welded enclosure with separate, sealed cooling air circuits for power modules and controls.

Acutrol III / IGBT represents a breakthrough in compatibility with mine distribution systems. Incoming AC power is converted into DC with a so called Active Front End (AFE) replacing the normal SCR input rectifier. Benefits include a 1.0 power factor without reactive power compensation equipment, record low total harmonic distortion of less than 5%, and high tolerance for input voltage fluctuations.

Troubleshooting becomes easy with our new, touchscreen diagnostic computer. Easy to read graphics and text messages help the electrician to find a faulty component, troubleshoot the fault, run test routines, and observe the function of the system during operation. An ethernet radio link will allow access to the diagnostic computer from a remote station in the near future.

Acutrol III / IGBT is setting out to become the drive system of choice for electric mining shovels. This will be achieved with technology helping the customer to achieve his ultimate goal – lowest costs per ton.