# Single Line Diagram vs Load-Flow Model: Validation Before Analysis

> Check connectivity, units, operating cases and result validity before using a single line diagram for electrical engineering decisions.

- **Category:** Single Line Diagrams
- **Author:** Voltformer
- **Publication Date:** 2026-09-27
- **Reading Time:** 5 min read
- **Key Tags:** #SLD, #Single Line Diagram, #Engineering
- **Canonical URL:** https://voltformer.com/articles/single-line-diagram-load-flow-model-validation
- **Markdown Source:** https://voltformer.com/articles/single-line-diagram-load-flow-model-validation.md

### 1. Separate appearance from connectivity

A readable single line diagram can still contain an electrically disconnected terminal, an open switch or a missing source reference. Inspect the model’s connections rather than relying on symbol proximity. Check both sides of each transformer and identify every energized island and its reference source.

Start with an input register: source data, equipment ratings, transformer impedance and connection, branch impedance, load convention and switching state. Retain the source and unit of each value.

### 2. Check what the selected study needs

Different studies need different inputs. A load-flow case uses demand and source assumptions; a fault study needs appropriate source and network impedances; protection work needs device settings and current bases. A valid drawing cannot supply missing engineering data.

| Check | Question before accepting a result |
|---|---|
| Units | Are V/kV, W/kW and VA/kVA consistent? |
| Topology | Is the intended feeder energized in this case? |
| Solver | Did it converge, and are any outputs unavailable? |
| Scope | Does this model represent the physical case being studied? |
| Review | Can another engineer reproduce inputs and assumptions? |

Use Voltformer’s readiness and warning information with the results. Do not convert an unavailable result into zero, or treat an empty warning table as evidence of complete study coverage.

### 3. Make results reproducible

Retain a baseline case before changing loads, sources or switch positions. Compare the same case against an accepted reference using tolerances agreed in advance. Investigate changes in losses, bus voltages and unsupplied loads rather than checking only one headline number.

Save a revision, export the study package where supported, and preserve equipment data and solver settings. Agent-driven workflows should read the current document before saving with its expected version. Version conflict protection reduces overwrites; it does not replace engineering review.

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[Voltformer SLD](/single-line-diagram-editor) · [API](/agent-api#tool-getSldCapabilities) · [ETAP Alternative for Single Line Diagrams: A Practical Selection Guide](/articles/etap-alternative-single-line-diagram-editor) · [How to Create an Electrical Single Line Diagram Online](/articles/how-to-create-electrical-single-line-diagram-online)

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- [Machine-Readable API Catalog](https://voltformer.com/agent-catalog.json): Autonomous agent catalog data.