Fully utilizing the intelligent electronic device capability to reduce wiring in rural electric distribution substations

Each wired termination in a substation represents a cost associated with engineering, installing and testing that wired point. These costs include the obvious financial labor costs, but also include intangible costs such as installation and commissioning time, potential for human error, panel space, increased resistive burden in circuits, and larger raceways. Additionally, each wired termination represents stranded engineering time that is used design these terminations rather than allowing the engineering staff to solve problems. Most rural electric distribution wiring design practices are taken for granted without thought as to the true cost and reliability of the practice and whether or not the function can be implemented with less wiring. Some standard rural electric distribution practices have evolved that seek to minimize wiring. An example of this practice is the use of multifunction microprocessor based relays that can logically develop a trip bus from protective elements rather than having to wire individual elements to create the same trip bus. This paper seeks to expose some of the hidden financial costs and reliability costs associated with copper process wiring. Additionally this paper will discuss ways in which modern IEDs can be fully implemented to further reduce wiring. The cost and reliability benefits associated with the reduced wiring will be discussed and quantified. Some of the solutions to be addressed include the use of breaker IEDs as an interface for breaker control, IED to DCS communications, IEC 61850 IED to IED communications, internal lockout Relays, IED pushbutton control, and process bus. Each of these solutions are currently available in today´s market place and have varying degrees of acceptance within the industry. The benefits and liabilities of each solution using traditional IED implementation versus maximized IED implementation shall be discussed.