This simulator follows electrical service the whole way from the utility supply to a building load: utility → step-down transformer → service conductors → switchboard → panel → load. A 3D model with a selectable-part inspector lets you click any stage of that path while a full set of controls lets you change the utility supply, transformer, service and load parameters and watch every downstream value respond.
• A 3D power-path model with a part selector (click any component — transformer, service conductors, switchboard, panel — for its details) and Reset Camera / Hide Labels controls. • Utility supply controls: line-line voltage (HV, in kV) and frequency (Hz). • Transformer controls: rating in kVA, impedance (%Z), and secondary line-line voltage configuration — 208Y/120V, 400Y/230V, 480Y/277V or 600Y/347V. • Service controls: conductor length (m) and conductor area (mm² Cu). • Load and demand controls: building power factor, load demand as a percentage of connected load, and connected load in kW. • Protection control: main breaker trip setting as a percentage of transformer full-load-amp equivalent. • Fault mode selector: None, Sustained overload, Open service conductor, Transformer overtemperature, Panel bolted fault, or Poor power factor. • Start/Pause/Step (+0.1 s) simulation-time controls with Export JSON, a live measurement grid, an event log, and guided experiments.
Utility power arrives at a much higher voltage than any building load can use directly, so a step-down transformer converts it to a standard secondary configuration — the simulator lets you pick between 208Y/120V, 400Y/230V, 480Y/277V and 600Y/347V, the same secondary voltage families used in real low-voltage building service design. Transformer rating (kVA) sets how much load it can carry, while impedance (%Z) determines how much the secondary voltage sags under load and how much fault current the transformer can deliver into a downstream fault — both directly affect the numbers you see everywhere downstream in the model.
Service conductor length and cross-sectional area (mm² Cu) set the resistance of the run from the transformer secondary to the switchboard, which produces voltage drop under load exactly as it would with the panelboard branch-circuit model, just at the service-entrance scale rather than a branch-circuit scale. Connected load and load demand percentage let you model realistic diversity — real buildings rarely draw 100% of their connected load simultaneously — while power factor determines how much of that current is actually doing useful work versus circulating reactive current.
The five fault modes (sustained overload, open service conductor, transformer overtemperature, panel bolted fault, poor power factor) each stress a different part of the path, and combined with the main breaker's trip-setting percentage, let you see exactly which protective device responds to which condition and how the measurement grid and event log capture that response as it happens.
Utility power is delivered at a much higher voltage than building equipment and wiring are rated for, both for transmission efficiency and safety. A step-down transformer converts the utility's high voltage to a standard low-voltage secondary configuration (such as 208Y/120V or 480Y/277V) that panelboards, switchboards and building loads are designed to use directly.
Higher transformer impedance causes more secondary voltage sag under load but limits the fault current the transformer can deliver into a downstream fault; lower impedance does the opposite. This tradeoff is why %Z is a key transformer specification that affects both normal voltage regulation and protective device coordination throughout the building.
Connected load (kW) is the total capacity of everything that could draw power if fully on; load demand is expressed as a percentage of that connected load and represents what is actually being drawn at a given moment, since real buildings have diversity — not everything runs simultaneously at full capacity. Adjusting both separately lets you see how actual operating conditions differ from the building's theoretical maximum draw.
Sustained overload, open service conductor, transformer overtemperature, panel bolted fault and poor power factor each represent a distinct real-world failure or degraded-operation condition, stressing a different part of the utility-to-building path. Injecting each one while watching the live measurement grid, event log and main breaker trip-setting response builds intuition for how a real power system reacts to and protects against different fault types.