This simulator models four common substation bus arrangements — single bus, main-tie-main, ring bus and a breaker-and-a-half diameter — as an explicit connectivity graph. Switch topologies, open and close breakers, remove a source, or apply a bus-zone fault, and see exactly which circuits stay supplied and which lose service.
• A real-time 3D bus workbench — sources, bus conductors, labeled circuit breakers (CB1–CB5), two protected circuits and zone protection — with camera home view, focus-selected-part, toggleable enclosure, auto-rotate, expand and tap-to-inspect components. • A bus-arrangement selector (single bus, main-tie-main, ring bus, breaker-and-a-half diameter), a breaker-to-operate selector (CB1–CB5), source A and source B availability checkboxes, and a permit-synchronized-source-paralleling checkbox. • Play/pause, single step, larger step, and 0.1×/1×/10×/60× playback speed. • Actions to toggle the selected breaker, apply a bus-zone fault, and remove the fault while keeping breakers open. • A Connectivity & availability analysis tab with two live charts, the underlying model equations (graph reachability, closed-breaker conduction, bus-fault isolation), and snapshot measurements. • A Test & diagnose style Experiments tab with five guided experiments, an independent model-verification bench, and a timestamped event log with a copyable trial report. • A Learn & assess tab with guided lessons, a knowledge-check quiz and a written scope statement with a reference link.
The simulator treats each arrangement as a graph: sources, buses, breakers and circuits are nodes and edges, and a circuit is supplied only if a healthy path connects it to an available source through closed breakers. In a single-bus arrangement there is exactly one path per circuit, so opening the wrong breaker — or losing the one bus — strands every circuit downstream. Main-tie-main splits the bus into two sections joined by a normally open tie breaker, so if one source is lost, closing the tie can let the surviving source reach both sections, but only after synchronization permission is granted in this teaching interlock.
A ring bus and a breaker-and-a-half diameter both build in redundancy: the ring closes the bus into a loop so most single-breaker openings leave an alternate path, and breaker-and-a-half uses three breakers to serve two circuit positions, with the shared middle breaker introducing its own maintenance and failure considerations. A bus-zone fault opens every breaker incident to the faulted node — the simulator models selective isolation, not a decorative fault flag.
The metrics panel reports circuits supplied, total circuits, closed breakers, breakers in the current arrangement, and whether each source is available — all computed by walking the graph from available sources through closed, healthy edges. This is a logical service-availability model: it does not solve power sharing, fault current magnitude, relay selectivity, breaker-failure backup schemes, or synchronism checking. The source-paralleling permission is a logical fixture representing an interlock, not a measured phase-angle or voltage match, and only one breaker-and-a-half diameter is modeled rather than a full multi-diameter station.
Single bus has one bus section and no redundant path, so a single breaker or bus outage can strand circuits. Main-tie-main splits the bus into two sections with a normally open tie breaker that can be closed to restore service from the surviving source. A ring bus closes breakers into a loop so most single-breaker openings leave an alternate path. Breaker-and-a-half uses three breakers to serve two circuit positions between two buses, giving redundancy at the cost of a shared middle breaker.
It models the arrangement as an explicit connectivity graph and checks reachability: a circuit is supplied only if a healthy path of closed breakers connects it to at least one available source. Opening a breaker removes an edge from that graph, and a bus-zone fault removes a node along with every breaker connected to it, so the simulator reflects graph-based isolation rather than a simple on/off toggle.
The tie breaker starts open, separating two potentially live bus sections. Closing it between two energized sources without matching voltage, phase angle and frequency risks a severe out-of-phase closing event, so the simulator models a synchronized-paralleling permission as a teaching interlock before the tie can be closed.
This is a logical service-availability model, not a power-flow or protection-coordination study. It does not solve power sharing between sources, fault current magnitude, relay selectivity, breaker-failure backup, or an actual synchronism check — the source-paralleling permission is a logical fixture. Only one breaker-and-a-half diameter is shown rather than a full multi-diameter station.