Automation Readiness: AC or DC Cranes

Automation Readiness

Many of our clients and potential clients who are considering automation of older cranes have to make the decision to retrofit an older DC crane or purchase a new automation ready AC crane. The following is some considerations for calculating the ROI on whether to retrofit or purchase new:

Energy Savings
  • Many older cranes operate using DC power since when those controls were built, DC was much easier to supply and provided the power load necessary to drive large and heavy pieces of industrial equipment. Since that time, AC technology has advanced dramatically. Today, switching from an old DC powered crane to a new AC powered crane provides a dramatic decrease in power consumption. In some cases, power consumption can be lessened by as much as 50%. Newer, more compact, lower HP motors powered by AC draw a fraction of the amperage in comparison to the older, higher HP DC counterpart.
  • An automated crane environment does not require climate control or lights to operate. This results in significant energy savings over the course of one year. For example, at a Natural Gas cost for heating @ $1.25 per square foot over the course of a year and Electricity cost for lighting @ $0.68 per square foot over the course of a year, a 20,000 square foot facility can expect to save $38,600 dollars on utilities alone.
Maintenance / Sustainability / Green Initiatives
  • By making the switch to AC power, facilities will see savings as it relates to production downtime. Most facilities that depend on DC powered cranes know that a malfunction can turn into a major problem, seeing as most DC technology is no longer available as far as replacement parts are concerned. Even worse is the fact that DC parts are very expensive and require long lead times – sometimes as much as 6 months to a year. Furthermore, DC crane contactors allow for a huge inrush of current, which results in stress on equipment (think of flooring a car from 0 to 60). In contrast, AC power improves the longevity and life expectancy of a crane. Variable frequency drives of AC systems substantially extend the life of cranes since there is less wear and tear on motors and mechanical parts. In an automated environment, programmable speed curves are used to ensure that there are no harsh starts or stops in any direction. This also ensures that no product gets damaged. From an environmental perspective, DC cranes typically require more maintenance, due to their age and the added stress that is imparted on the crane due to the use of DC power. The need for more wear parts and spare parts means that DC cranes have a more significant negative environmental impact in comparison to their automated AC counterpart. In most cases, depending on the working environment, you can witness a savings of 20 to 50% on wear parts and spare parts.

There are a lot of additional considerations when looking to automate an older DC crane versus purchasing a newer AC crane, these could include:

  • Age of the existing crane, what would be the replacement timeline on the crane regardless of any Automation Project
  • Lost production / uptime for the retrofit crane versus installing a new AC crane off to the side with minimal production interruption
  • Overall optimized automation program for the facility and where this fits in with the plan

If you are unsure of the right optimized automation plan for your facility contact CareGo today, we offer engineering services to evaluate the options in front of you and provide the necessary information to help to make the right decision for you and your operations.

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