Fiber Optic Network Design

Location: Willmar, Minn.

Client: Willmar Minnesota Municipal Utilities Commission

Completion Date: 1997

Willmar Municipal Utilities (WMU) retained Burns & McDonnell to handle the design of its new substation and transmission facilities and to develop the design for an affordable yet reliable communications network. The new communications system would not only serve the new electrical facilities associated with the project but would replace the aging and unreliable buried telephone cables that served three other locations. 

  • Fiber optic design
  • Digital microwave design
  • Utility network design

As copper conductor pairs began to fail on their aging direct-buried telephone cables, Willmar Municipal Utilities (WMU) decided to implement a new and more reliable system of communications for their substation telephone, SCADA and protective relaying applications. The time to remedy the problem came in 1996 as WMU embarked on the design and construction of a new 69/12-kV substation and transmission line to serve the growing demand for power in Willmar, Minn.

Burns & McDonnell analyzed several alternatives. Looking to the future, WMU wanted to invest in fiber optics, but the costs were prohibitive for the total network. Fiber optic ground wire (OPGW) was justified for installation on the new transmission line. This fiber optic link spanning from WMU’s Willmar Substation to the newly constructed Southwest Substation, was combined with three hops of 6-GHz spread-spectrum digital microwave radio to form a secure loop-protected digital communications network.

The network serves WMU’s power generating plant, South Substation Willmar Substation, and the new Southwest Substation in a self-healing ring configuration. Intelligent T-1 multiplexers, specially designed for utility substation applications, have the capability to automatically sense a failure in the network and reroute signals around the failed segment.

Burns & McDonnell performed all design functions for the new system, application engineering, drawings, specifications and inspection.

  • Fiber optics
  • OPGW
  • Redundant rings
  • Digital microwave
  • Protective relaying