A **Single Line Diagram (SLD)** is a simplified representation of an electrical power system. It provides a one-line overview of the connections and components within an electrical network. The SLD uses standardized symbols to represent elements such as transformers, generators, circuit breakers, and switches, showcasing how power flows from the source to the load [[1](https://www.iacsengineering.com/single-line-diagram-sld/)]. ### Main Inputs and Outputs of an SLD: 1. **Inputs**: - **Power Sources**: These include generators, utility supply, or renewable sources, indicating voltage levels and type of connection to the system [[2](https://www.studyforfe.com/blog/fundamentals-of-single-line-diagrams/)]. - **Transformers**: Transformers that step-up or step-down voltage as power moves through the network. - **Protection Devices**: Components like circuit breakers and relays that manage safety within the system. 2. **Outputs**: - **Loads**: The representation of electrical devices or systems drawing power, such as motors or lighting systems. - **Switchgear**: Various switchgear components showing how the flow of electricity is controlled within different parts of the network. - **Monitoring Indicators**: These could include relays or sensors to illustrate the state of different parts of the system for control and situational awareness [[4](https://www.copadata.com/en/industries/energy-infrastructure/energy-insights/control-and-situational-awarness-single-line-diagram/)]. The SLD provides clarity for engineers to design, operate, and maintain electrical infrastructure efficiently.