Explore how transformer volts per hertz sets core flux, how the B–H loop approaches saturation, why magnetising current becomes distorted, and how switching angle and residual flux influence energisation inrush.
Scope: Educational reduced-order transformer-core model. Use measured material data and appropriate electromagnetic/transient software for design, protection settings or equipment studies.
Bpk≈ V / 4.44 fNA
B–Hhysteretic material
Saturationpermeability collapses
Currentbecomes distorted
01 // Interactive transformer core simulator
Use the overview for the complete V/Hz → flux → hysteresis → current chain, then move into the detailed B–H, waveform, energisation and core-loss experiments.
Core, B–H loop and waveforms
normal excitation
2.5D CORE VIEW // NONLINEAR MAGNETIZATION MODEL
What to watch: Higher V/Hz pushes the core toward saturation. The B–H operating point moves toward the knee and the magnetising-current waveform becomes increasingly distorted.
—peak flux density
—Bpk / Bsat
—V/Hz vs nominal
—magnetising-current index
—relative core-loss index
B–H loop
detailed material view
DETAILED CORE VIEW // NONLINEAR MAGNETISATION MODEL
Detailed mode. —
02 // Why volts per hertz matters
For a sinusoidally excited winding, the voltage, frequency, number of turns and core area set the peak flux density.
TRANSFORMER EMF
Bpk ≈ Vrms / (4.44 f N A)
Higher voltage increases flux. Higher frequency, more turns or a larger core area reduce flux for the same applied voltage.
SATURATION
Near the material’s saturation knee, incremental permeability falls. Producing a little more flux requires disproportionately more magnetising force H and therefore more current.
HYSTERESIS
B does not follow H along a single reversible line. The loop area represents energy dissipated per magnetic cycle; practical core loss also includes eddy-current and other frequency-dependent contributions.
03 // V/Hz operating gauge
Use this as an intuition aid: pushing the calculated peak flux beyond the illustrative knee drives the nonlinear current waveform.
Model scope: the overview uses the steady-state V/Hz saturation model. The Energisation inrush tab adds switching angle, residual flux and a reduced-order source/winding resistance limit. The Core loss split tab uses a normalized hysteresis-like and eddy-current-like loss index at the present flux density; it is not W/kg data and is not a substitute for measured electrical-steel loss curves.
Frequently asked questions
Short explanations of the effects shown in the simulator.
For sinusoidal excitation, peak flux density is approximately V/(4.44 f N A). With voltage, turns and core area unchanged, reducing frequency increases volt-seconds per cycle and therefore increases the required core flux swing.
Near the knee of the B–H curve, incremental permeability falls sharply. The applied voltage still demands a nearly sinusoidal flux waveform, so disproportionately more magnetising force H—and therefore winding current—is needed near the flux peaks.
Flux is the time integral of winding voltage. Closing angle and residual core flux can add a large decaying offset to the normal AC flux, temporarily driving the core deep into saturation and producing a large asymmetric magnetising-current transient. The current magnitude also depends on source and leakage impedance, which this reduced-order model does not solve in full.
No. The loss tab reports a normalized teaching index that separates hysteresis-like f·Bⁿ scaling from eddy-current-like f²·B² scaling. Actual W/kg depends on grade, lamination thickness, processing, waveform, temperature and manufacturer test data.
Background, assumptions & references
Open these notes when you want the engineering detail behind the animation.
The numeric outputs use the equations and reduced-order relationships described on this page. The core rendering, flux glow, B–H trajectories and waveform animations are schematic teaching visuals rather than finite-element electromagnetic results. For this transformer page, peak sinusoidal flux is calculated internally from the exact integrated-sine relation; the familiar 4.44 coefficient is shown as the rounded engineering form. The B–H material presets are representative teaching curves rather than manufacturer datasheets, the inrush mode is a reduced-order flux-offset model, and the loss tab reports normalized indices rather than W/kg.
No. The simulator is intended for education, screening and intuition. Actual equipment selection and design should use manufacturer data, applicable standards and project-specific analysis.