C&I Engineering

Main-Tie-Main Switchgear Configuration


C&I completed the Feasibility, Definition, and Implementation phases of this infrastructure upgrade project in order to improve the electrical reliability for the Crude unit. To accomplish this, the existing single–source design with one (1) 13.8kV feeder and one (1) transformer at each voltage level was converted to a dual feed system with two (2) 13.8kV feeders, two (2) transformers, and a Main-Tie-Main (MTM) switchgear configuration at all voltage levels. To provide feed diversity, a second 13.8kV feeder from a separate substation was installed.  Additional reliability was achieved by extending the Main-Tie-Main philosophy to each of the downstream distribution voltage levels (4.16kV, 2.4kV, and 480V), which required dual transformation and double ended switchgear at each voltage level. 

To support the new electrical gear, a Power Distribution Center (PDC) was installed to house the 13.8kV and 4.16kv gear.  The existing brick substation was substantially modified internally to house the new 2.4kV and 480V gears.  In order to make this happen, the gear in the existing substation was removed and new gear was installed and tested on-site during a tight shutdown window, putting it on the critical path of the turnaround. Since there were other major upgrades occurring in the unit at the same time, C&I took the lead on a weekly coordination meeting with another engineering firm.

In addition to improved reliability, personnel safety was enhanced by providing arc resistant switchgear in a new PDC and electronic relay protective systems, providing high speed detection and clearing of electrical faults on the 13.8kV lines, transformers and switchgear buses at all voltage levels.  For added redundancy, the pump loads were redistributed so that A/B paired pump loads are split to separate switchracks fed from separate sides of the 480V MTM switchgear.  Three (3) new switchracks and a MTM configured MCC was included for the pump load redistribution and future 480V load expansion.  The 480V feeds to the switchracks were placed in a new cable tray system extending from the existing substation. 

What We Did...

This Project’s Team

  1. John Droste

    Project Manager

    Meet John