For decades, the ability to control motor speed (frequency), direction and torque was limited to DC motors. Industries of all types optimized processes for the power and control that DC voltage provided. Entire Segments of industry were designed around these processes and they have served industry very well for years. We might say to ourselves, “why change?” or “what i have still works fine”. With today's motivation and incentives for clean, efficient energy, modern industry requires more from each of us- more responsibility, more reliability, and more functionality; all on the same budget.
For years now, the development of Pulse Width Modulation (PWM) has made the ability to use AC power or Variable Frequency drives/motors commonplace on today's Container Crane or Yard RTG/RMG and Stacking crane projects. A green, cost effective alternative is finally at our fingertips. Yet, not everyone is able to benefit or can justify the cost of making these, often, expensive upgrades. To replace DC Drives and Motors with AC can cost hundreds of thousands of dollars, causing smaller operations to choose not to upgrade or simply not to justify the investment.