Resistor-Controlled Slip-Ring Motor → Modern VFD-Based Motion Control
DSC Engineering upgraded MHE Demag 60-tonne overhead cranes from resistor-controlled slip-ring motor systems to modern Invertek Optidrive P2 VFD-based hoist, LT, and CT motion control. Existing resistor banks were repurposed as dynamic braking resistors, absorbing regenerative energy during lowering operations and preventing DC bus overvoltage trips.
DSC Engineering Solution
- Conversion of slip-ring motor configuration for inverter operation
- Reuse of existing resistor banks as dynamic braking resistors
- Dedicated VFD systems for Hoist, LT, and CT motions
- Upgrade of crane control panels, power distribution, and control circuits
- Full commissioning, tuning, and performance optimization
Project Impact
- Smooth stepless speed control for lifting and travelling motions
- Improved load handling accuracy and operator control
- Reduced mechanical stress on motors, gearboxes, and brakes
- Lower maintenance and extended crane asset life
- Enhanced safety during steel coil handling operations
- Extended crane asset life — avoided costly full crane replacement