Transformer Vector Group & Polarity Visualizer

Transformer vector groups — Dyn11, YNd1, Dd0, Yy0 — encode the winding connection and phase shift in a compact notation that protection engineers, relay technicians, and substation designers must read fluently. But the relationship between that notation and the actual phasor diagram is rarely taught interactively. This visualizer lets you select any winding combination (Delta-Wye, Wye-Delta, Delta-Delta, Wye-Wye), set the clock-hour number representing phase shift, configure turns ratio, and immediately see the primary and secondary phasor diagrams update with annotated voltage vectors. The Winding tab shows the physical winding configuration with dot convention polarity marks. The Vector Group tab maps the IEC designator to the equivalent clock-hour diagram. The Phasor tab provides a detailed view of both primary (HV) and secondary (LV) voltages with measurements. The Design tab presents design challenge problems around vector group selection. The Scenario tab provides predefined configurations. Inputs include voltage sequence (ABC positive or ACB negative) and loading condition (balanced, unbalanced, single-phase). An essential tool for engineers reviewing protection schemes that rely on CT ratio and vector group compensation in 87T differential relays.

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A live look at the app you'll launch — every control on the left drives the visualizations on the right in real time.

• 01Interpret an IEC vector group designation (e.g., Dyn11, YNd1) and identify the winding connection and phase shift it encodes
• 02Draw the primary and secondary phasor diagrams for Delta-Wye and Wye-Delta connections and identify the 30° phase shift
• 03Explain dot convention polarity marks and use them to determine the relative polarity of primary and secondary voltages
• 04Explain why a Dyn11 (30° shift) transformer requires CT ratio and angle compensation in an 87T differential relay
• 05Distinguish balanced, unbalanced, and single-phase loading conditions and predict their effect on secondary phasors
• 06Select the appropriate vector group for paralleling two transformers given a requirement that secondary voltages must be in phase

Compare two designations and decide whether they can be paralleled.

No sign-in required. Progress is saved on this device.

• —Not a design document, stamped calculation, or approval record.
• —Not a substitute for engineering analysis by a licensed professional.
• —Not connected to live equipment and not a safety device.