This simulator models a single-phase inductive voltage transformer (PT/VT) — a high-turns primary winding across the system voltage feeding a low-turns secondary winding that supplies a metering or relay burden. Adjust the primary voltage, transformer ratio, burden and lead resistance, then watch how voltage phasors, core flux and secondary faults behave.
• A real-time 3D cutaway model of the inductive voltage transformer with a toggleable enclosure, home-view reset, auto-rotate orbit, expandable 3D view and pause/play animation control. • Adjustable primary voltage, transformer ratio, burden and lead resistance via the supply, nameplate & burden control panel. • Secondary circuit mode selector: rated impedance burden, secondary short (fault fixture), or open burden / high-impedance voltmeter. • A reversible X1/X2 secondary polarity checkbox and a leading/lagging burden checkbox. • A primary-source energize/de-energize checkbox, plus 100 ms and 1 s time-advance buttons and a replace-fuse button tied to a synthetic secondary fuse model and live fuse-status readout. • Four live scope charts: voltage fidelity (ideal vs. meter voltage), core flux density with saturation-onset markers, secondary current, and voltage phasors (ideal reference, induced voltage, meter voltage). • A calculated-quantities panel with ratio error and the governing equations. • A tabbed workflow across four pages — VT workbench, Signals & equations, Experiments & tests, and Learn & assess. • Guided experiments, a 'Model verification bench' that runs built-in model checks, a diagnostic challenge exercise with a diagnosis selector, and a knowledge-check quiz with feedback and reset. • A session log recording actions, and an export-results-to-JSON button.
A PT is a step-down voltage transformer connected across the high system voltage rather than in series with the line current. Its ideal transformation follows a = rated Vp / rated Vs, giving an ideal secondary voltage of Eideal = Vp / a. In practice, series winding impedance (Z1 on the primary side, Z2 including secondary lead resistance) and the magnetizing branch (Ymag) cause the actual induced voltage E to differ from Eideal, following E = Eideal / [1 + Z1(Ymag + 1/(Z2 + Zburden))].
Unlike a current transformer, a PT can safely supply an open secondary — no dangerous voltage spike results — but a short-circuited secondary is the dangerous condition here, because the low-impedance PT tries to drive very high current into the fault. This simulator represents that with a generic secondary fuse governed by a synthetic inverse-time I²t accumulation, which will eventually operate and can be reset with the replace-fuse control.
The voltage fidelity chart compares the ideal transformed voltage (amber) against the actual meter voltage (mint) over one steady-state cycle. The phasor chart shows three vectors: the ideal voltage reference (amber), the internal induced voltage E (violet), and the meter voltage (mint) — the angular and magnitude gaps between them visualize how winding impedance and burden distort both magnitude and phase.
Secondary current is Is = E / (Z2 + Zburden), and meter voltage is Vmeter = Is × Zburden, with rated burden impedance sized as Zburden = rated Vs² / rated VA. Core flux is reported as Bpeak = |E| / (4.44288 f Ns A), letting you see how close the core sits to the modeled saturation onset. Ratio error is (|Vmeter| / Eideal − 1) × 100%. This is a generic single-phase inductive VT model — not a capacitive voltage transformer (CVT), not a manufacturer accuracy-class certification, and the fuse behavior is illustrative rather than a certified clearing-time curve.
A potential transformer works like a conventional voltage transformer: a primary winding with many turns is connected across the high system voltage, and a secondary winding with fewer turns produces a proportionally reduced voltage, following the turns ratio a = rated Vp / rated Vs. The reduced secondary voltage can then be safely measured by relays and meters.
Unlike a current transformer, a potential transformer can tolerate an open secondary, but a short-circuited secondary draws excessive current because the PT is essentially a low-impedance voltage source. This simulator models a generic secondary fuse using a synthetic inverse-time I²t accumulation, and a short-circuit fault will eventually operate that fuse.
Burden is the impedance connected across the PT secondary, sized from rated VA and rated secondary voltage as Zburden = rated Vs² / rated VA. Series winding impedance and lead resistance both cause the actual meter voltage to differ from the ideal voltage, which is reported in this simulator as a percentage ratio error.
The core flux density chart shows peak flux relative to a modeled saturation onset, computed from Bpeak = |E| / (4.44288 f Ns A). The phasor chart plots the ideal voltage reference, the internal induced voltage E, and the actual meter voltage, so you can see how winding impedance and burden introduce both a magnitude and phase difference between them.