This simulator models a generic thyristor soft starter feeding a squirrel-cage induction motor. Inspect the antiparallel thyristors, heatsink and bypass contactor while comparing voltage-ramp acceleration against a configurable current limit, then verify the model against a built-in check bench.
• 01 / Motor laboratory: a real-time 3D test bench (housing, stator, windings, rotor, shaft, bearings, fan, guard, six-terminal box, six thyristor power devices, heatsink, bypass contactor, main contactor K1, isolator and a firing/ramp monitor) with home view, focus-selected-part, cutaway, exploded view, auto-rotate and expand/hide-labels controls, plus start, stop/coast, reset trip, apply locked rotor and release-shaft actions, a run/pause toggle, 0.02 s and 0.2 s step buttons, and playback speed from 10x slow motion to 20x faster. • Settings: line-to-line supply (200-460 V), supply frequency (40-60 Hz), motor poles (2/4/6), load torque, load law (constant vs quadratic fan/pump), combined inertia, initial voltage fraction, requested voltage ramp time, current limit (1.5x-5x the 18 A base) and stalled-start timeout, plus a lock-the-shaft checkbox. • 02 / Curves & measurements: an illustrative chopped thyristor waveform chart, a voltage-and-current history chart, the underlying model equations, and live snapshot readouts of rotor speed, fundamental RMS current, applied equivalent voltage, torque, elapsed start time and illustrative firing angle. • 03 / Experiments: four guided scenarios (fan-load soft start, tight 2x current limit, insufficient starting torque with a constant 45 N·m load, and a locked-rotor timeout test), plus a Verification bench that runs automated model checks against fresh independent models, and a timestamped event log with a prepared trial report you can copy. • 04 / Learn & assess: four lessons (thyristors change applied voltage, current limiting can limit acceleration, bypass is a distinct state, a ramp setting is not a guaranteed start time), a two-question knowledge-check quiz, and a written scope-and-references statement linking to an ABB soft-starter technical reference.
The motor is a generic balanced fundamental-frequency induction-motor equivalent circuit (Rs=0.65 Ω, R2′=0.45 Ω, Xs=X2′=1.1 Ω, Xm=28 Ω at 50 Hz on a star-equivalent base, with reactances scaling with frequency). Synchronous speed and slip set the rotor branch impedance R2′/s, from which stator current, air-gap power and electromagnetic torque are computed each step, and mechanical speed integrates J dω/dt = Te − Tload − 0.012ω.
The soft starter reduces the effective stator voltage below the requested ramp value whenever doing so is needed to respect the configured current limit — the applied voltage is the lesser of the ramp voltage and the voltage needed to satisfy the limit. After full requested voltage is reached and the rotor is up to sufficient speed, the model closes the bypass contactor so the SCR path no longer controls voltage. The displayed chopped waveform and illustrative firing angle use a resistive-load RMS identity purely for visualization — actual inductive thyristor commutation, harmonics and torque ripple are not solved.
The voltage/current history chart plots the fundamental RMS envelope over physical simulated time as the starter ramps voltage under the current limit; the chopped waveform panel is a separate illustrative visualization tied to the same computed voltage fraction, not a true switching-transient solver. Watch how a tighter current limit slows acceleration and can leave a heavily loaded or locked rotor unable to reach bypass before the stalled-start timeout trips.
Per the model's stated scope, this is a generic representative starter (not a manufacturer-specific product): iron loss, saturation, unbalance, harmonics, bearing dynamics and subcycle switching transients are not solved, the starter does not vary supply frequency, and the firing-angle/waveform display is illustrative only rather than a solved inductive-commutation waveform.
A thyristor soft starter controls the applied line-frequency voltage using antiparallel SCR pairs per phase — it does not change electrical frequency. In this simulator, the effective voltage ramps up under a configurable current limit until the motor reaches bypass.
No. A tighter current limit reduces the voltage — and therefore torque — available to accelerate the load. The experiments tab includes a scenario where a low limit combined with a 45 N·m constant load leaves the rotor stalled until the start times out.
After the requested voltage ramp completes and the rotor reaches sufficient speed, the model closes the bypass contactor so the thyristor path no longer controls voltage. The semiconductor package remains visible in the 3D scene, but current no longer flows through it.
The Experiments tab includes a Verification bench that runs automated checks against fresh, independent copies of the motor and soft-starter model without disturbing your current trial, plus a timestamped event log and a copyable trial report.