230kV Bells Mill Rd – Replace Transformer

230kV – Bells Mill Road Substation

Replace Transformer (WR# 3429028) – Rockville, Maryland

Project Scope:

Realtime Utility Engineers, Inc. (RUE) provided civil and electrical engineering to replace an existing 230/69kV, 220MVA transformer, along with replacing the transformer protection relays, and fire walls.  Design drawings included the installation of one (1) 280MVA, 220/69/13.8kV power transformer.  RUE’s design also included retrofitting two (2) relay panels to include one (1) GE-T60 and one (1) SEL-387T for transformer protection.

Detailed engineering included:

  • Providing engineering calculations, wall footings, and foundation sections to accommodate new piers and columns
  • Preparing calculations for oil containment capacity
  • Providing the interface from the new protection relay alarms, to the existing substation RTU

bellsmillreplaceDesign Challenges & Solutions:

The existing wall foundations were not adequate for installing the proposed, new (3)-wall containment enclosure.  The existing footing/wall foundation system required reinforcement by installing foundation footings and piers, to support masonry wall columns, or pilasters (perimeter wall), along the long wall section and in the SE and SW corners.  Realtime developed design details of connecting old concrete structure to new concrete structure for the wall foundation.