Industrial Manufacturing Facility – Site Medium Voltage Evaluation & Detail Design



A large industrial manufacturing Client requested investigation of existing aging unit substations at an existing operating facility located in Decatur, Alabama to determine a renewal plan for the site.   


Fifteen existing unit substations ranging from 1000 kVA to 2000 kVA were at various stages of their rated operating lifetime and needed to be evaluated to determine fitness for their current application considering age, feeders, peak loading, loads served, equipment and electrical room dimensions.  The Client needed the development of a renewal plan that considered plant operability, reliability and personnel safety.


Excel Engineering contracted directly with the Client to provide the evaluation of existing equipment and the development of the unit substation renewal plan.   After a thorough evaluation of the plant equipment and operational considerations, Excel provided various options for consideration including installing a virtual main vs. secondary main circuit breakers and evaluating the ability to combine multiple unit substations into a single unit substation.  Additionally, Excel analyzed the medium voltage distribution design to develop a sequenced replacement plan focused on minimizing manufacturing downtime. 

Throughout the evaluation period project, Excel gathered input from various stakeholders and developed and maintained a priority list for constraints and replacement scenarios.  Six unit substations deemed high priority were queued for immediate replacement.  Preliminary fault current studies were performed on these substations to identify additional under-rated panelboards needing replacement.  Excel worked with equipment suppliers to provide equipment cost estimates and also developed budgetary installation costs for the Client’s consideration.


Following completion of the evaluation and development of the renewal plan, Excel assisted the Client with the detailed design and construction package development for substation upgrade or replacement.

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