Power Distribution and Management

DANGER: Are Your Electrical Single-Line Diagrams Out-of-Date or Missing?

Relax and let Schneider Electric experts manage and modernize your electrical SLDs for you

Single-line diagram Digital Twin

The electrical distribution network is the “lifeblood” of an operating factory, industrial site, mission-critical facility, hospital, or any commercial building dependent on power to serve its business needs. Safe, effective operation and maintenance (O&M) of the power system is an imperative. Along with power monitoring and building management systems, having an accurate, informative map of the electrical system is critically important. These maps are referred to as single-line diagrams (SLDs) or one-line diagrams (OLDs).

SLDs play a critical role throughout the lifecycle of the facility. In the design and construction phases, they serve as a key input to the creation of the construction documents. SLDs provide the necessary details about the electrical network to enable competing electrical contractors to make accurate pricing proposals or bids. Mistakes and misunderstandings about the design can result in project delays and costly change orders.

In the operations phase, preparing critical response plans begins with maintaining accurate SLDs. One-line diagrams enable electrical personnel to fully understand the design of the facility’s electrical distribution system. Whether it’s a new or an existing facility, the single line diagram is a roadmap for all future testing, technical studies, and maintenance activities done during the operation phase of the site. Well-maintained SLDs will help ensure safety, maintain regulatory compliance, reduce downtime, and make operations more efficient.

Given their safety-critical role in guiding operations and maintenance personnel in their day-to-day work on the electrical system, for many regions in the world, there is a regulatory requirement to maintain SLDs to ensure they reflect the current physical reality of the electrical network. As an example, National Fire Protection Association (NFPA) 70E (Chapter 2, under “General Maintenance Requirements,” Article 205.2) mentions, “A single line diagram, where provided for the electrical system, shall be maintained in a legible condition and shall be kept current.”

Despite this, in Schneider Electric’s experience, it is very common for SLDs to be out-of-date, exist as simple paper docs or static PDFs, or be outright missing. Instead, these sites have tended to rely on the internal tribal knowledge of the site’s electrician or engineering team and/or make the very risky assumption that original as-built drawings are correct enough. Operating in this dangerous way raises the risk of system downtime, injuries, or even death. Imagine, for example, if an upstream transformer had been replaced with one that has a lower impedance rating and that rating change was not reflected in the SLD. Operators may not know that the incident energy now exceeds safety limits at the low voltage switchboard or in the data center’s IT rack enclosure.

One of the reasons for sites being in this dangerous position is that it takes a significant ongoing commitment and effort by management and O&M teams to create and maintain SLDs over time. White Paper 520, “The Value of Accurate Electrical Single-line Diagrams (SLDs),” goes into what it takes to create and maintain accurate SLDs in some detail. Schneider Electric is answering this challenge by offering a new Electrical Digital Twin service in partnership with ETAP.

Electrical Digital Twin is a consulting service to create and digitize the client’s SLD and provide ongoing support to maintain and keep the model up to date on a recurring service agreement. After plant electrical data is collected, the Schneider Electric power system engineering team will deliver an ETAP model of the facility electrical system. Note, Schneider Electric’s engineering team of experts can also be contracted to do the data collection for the client. And with an ETAP base license for their power system engineering software platform, the client will have access to and ownership of the digital twin model that is created. This makes it easy to grant access to Schneider Electric for future studies and assessments, thereby avoiding the additional cost of having to collect new data for each study when they come up. Schneider Electric can also expand the scope of delivery upon customer request to include training, technical studies, and assessments such as arc-flash risk assessments. For those who lack the staffing and time to do all of this themselves, outsourcing the critical task of maintaining your SLDs to a qualified vendor like Schneider Electric is a sound idea.

To learn more about Schneider Electric’s new Electrical Digital Twin service, click here.


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