This simulator lets you build three-phase winding connections yourself — wye (star) or delta — on an interactive six-terminal board, then energize a live 3D RLC load bank to see exactly how the connection changes line and branch voltages, currents and power. It pairs a hands-on wiring exercise with a full circuit solver, phasor diagrams and a fault-injection test bench.
• Winding connections tab: a six-terminal board where you tap terminals to add or remove ideal copper links, with quick-load wye example, delta example and an incorrect-link challenge, plus a validate-and-apply step before the isolated wiring reaches the live circuit. • An isolated DC continuity meter (selectable probe pair, adjustable per-winding resistance) to trace U1–U2, V1–V2, W1–W2 winding pairs before energizing, plus a winding voltage-rating calculator against 230Δ/400Y and 400Δ/690Y nameplate examples. • Connection lab tab: a real-time 3D three-phase RLC load bank with wye/delta selector, load-neutral connect toggle, energize/open-contactor controls, time controls (run, step 0.1 s, step 1 s, advance 30 s), per-branch resistance and reactance (inductive or capacitive) controls with a copy-to-all-branches shortcut, and camera controls (isometric view, wiring view, auto orbit, expand). • A fault-fixture selector: open neutral, high-resistance neutral (20 Ω), open line A, open branch 1, low-impedance branch 1 short (0.1 Ω), or source phase B sag (30%), plus an overcurrent protection toggle with live protection status. • A virtual true-RMS voltmeter and clamp ammeter with selectable probe/clamp points across lines, neutral and branches, and a live circuit-measurements table with a diagnosis readout. • Phasors & waveforms tab: selectable voltage-vector view (branch, line-to-line, source phase) and current-vector view (line or branch), a waveform chart (branch voltage, line current, or instantaneous branch/total power) over two cycles, a phasor-proof formula panel, a power-accounting breakdown, and two-wattmeter method readouts. • Wye vs. delta comparison tab: a same-impedance or equivalent-balanced-load (ZΔ = 3·ZY) comparison mode, a break-before-make star→open→delta reconnection demonstration, and a resistance sweep chart comparing wye vs. delta line current across branch resistance 5–80 Ω. • Experiments & diagnostics tab: a 24-check verification bench that runs on isolated fixtures, a guided-experiments panel, a troubleshooting mystery-fault challenge with a diagnosis selector, and an exportable event log. • Learn & quiz tab: stepped lessons on isolated-to-parallel wye/delta behavior, model-scope notes, external references, and a knowledge-check quiz.
A three-phase source or load has three windings, each with a start and finish terminal. In a wye (star) connection, the finish end of every winding is joined at one common star point, and the three start ends go out to the line conductors; a neutral conductor can optionally be run from the star point back to the source. In a delta connection, the windings are joined end-to-end in a closed triangular loop, and each line conductor taps from one of the three junctions — there is no star point and no neutral.
Because the three phase voltages (or currents) are 120° apart, combining two of them by vector subtraction — rather than simple arithmetic subtraction — produces a magnitude that is √3 times a single phase quantity. In a balanced wye system this shows up as line voltage = √3 × phase voltage (while line current equals phase current). In a balanced delta system it's the reverse: line current = √3 × phase (branch) current, while line voltage equals phase voltage. Real power in a balanced three-phase system is P = √3 · VL · IL · cos φ regardless of which connection is used, as long as VL and IL are the actual line quantities.
The voltage and current phasor plots show RMS magnitude and angle, with the A-phase (or source-phase) vector fixed at 0° and angles increasing counterclockwise; in wye, a white vector marks the star point when it's displaced from its ideal zero position, which is a direct visual sign of an unbalanced or faulted neutral. The waveform chart shows two full electrical cycles at the supply frequency, with peaks at √2 times the RMS value shown on the phasor plot — a useful cross-check that both views agree.
The live measurements table and true-RMS meter let you probe any two points in the circuit and compare against the two-wattmeter power readout, which sums to total real power even when the load is unbalanced. The 24-check verification bench and the DC continuity reference readings (bare U1–U2 = 2 Ω, wye U1–V1 = 4 Ω, delta U1–V1 = 1.333 Ω, for a 2 Ω winding) give you a way to confirm the solver's Kirchhoff and vector math is behaving correctly before trusting the fault-diagnosis experiments.
In a wye connection, one end of each of the three windings is joined at a common star point, and the other ends connect to the three line conductors; a neutral can be brought out from the star point. In a delta connection, the windings are connected end-to-end in a closed loop, with each line conductor tapped from a junction between two windings, and there is no neutral point.
It comes from vector (phasor) subtraction of two 120°-apart sinusoidal quantities. In a balanced wye connection, line voltage equals √3 times phase voltage because it is the vector difference of two phase voltages. In a balanced delta connection, line current equals √3 times phase (branch) current for the same reason, applied to currents instead of voltages.
If the load is unbalanced and the neutral opens, the star point is no longer held at a fixed reference and shifts based on the relative branch impedances, causing branch voltages to become unequal — some rising above and some falling below the nominal phase voltage. A balanced delta load has no neutral and is unaffected by this fault.
In a three-wire three-phase system, total real power can be measured with only two wattmeters: W1 = Re[(VA − VB)·IA*] and W2 = Re[(VC − VB)·IC*]. Their sum equals the total real power delivered to the load, and this holds even under unbalanced conditions, without needing a third wattmeter unless a current-carrying neutral is present.