Vintage Low-Voltage Motor Control Centers – Replace or Upgrade?

摘要

Low-voltage motor control centers are universally applied in process industries. These electrical assemblies are perhaps one of the most dynamic in industry, ever changing as low-voltage motor loads are constantly added and modified in response to necessary process revisions and upgrades. As existing low-voltage motor control centers (MCCs) approach 40 to 50 years age, industry users are challenged with a decision to replace vintage MCCs approaching their end of life, or consider upgrade of existing assemblies. This paper will discuss upgrade versus replace alternatives, addressing UL 845 North American industry standard requirements and how this affects design, installation and maintenance of both upgraded and new MCCs. Application issues including considering the cost of replacing load cables versus re-use of existing cables, high-resistant pulsing ground systems and opportunities for process improvements and network communications that leverage the latest technology will be discussed. Finally, a case study comparing the alternative of replacing an existing MCC versus a field upgrade based on changing out all exiting starter and feeder circuit breaker units and an estimate of the total installed cost for both MCC replacement and upgrade for this application will be reviewed.