The Virtual Lab is an interactive fault-diagnosis simulator built on real SVG circuit schematics. You place probes, take readings on a simulated multimeter, and work through the same diagnostic logic you'd use on an actual panel — with zero risk and instant feedback.
Available Circuits
| Circuit | What It Simulates |
|---|---|
| Circuit A — 3-Phase Motor Control | 480V or 208V primary (toggleable), stepped down through a 4:1 transformer to a 120VAC control loop. Start/stop switches, motor starter (MS) coil, auxiliary sealing contacts, and overload (OL) protection. |
| Circuit B — 120VAC Parallel | Single-phase distribution and multi-load terminal block wiring — built for practicing circuit balance, loop integrity, and multi-fuse isolation. |
| Circuit E — Diode Testing (12VDC) | Low-voltage diode circuit for practicing forward/reverse-bias testing and identifying shorted or open diodes. |
Guided Mode vs. Challenge Mode
Guided Mode walks you through normal operation first, then lets an instructor-style control panel inject a specific fault (a blown fuse, an open motor starter, a tripped overload) so you can trace it methodically. Challenge Mode drops you into a circuit with an unannounced fault and scores you on probes used and diagnosis accuracy — the closer to real troubleshooting conditions.
How to Diagnose a Fault
- Establish a COM reference. Secure the black probe to a verified ground or neutral return.
- Trace voltage sequentially. Use the red probe upstream and downstream of fuses and contacts. Full voltage before an element but zero after it under demand means that element is open.
- Identify blown fuses. Full line voltage measured directly across a fuse terminal block means the fuse has blown.
- Check the overload relay. An open OL auxiliary contact breaks the coil circuit and drops the motor starter out.
The full walkthrough of this logic — including how parallel resistive paths can mask a fault — is in the Study Guide's Fault Diagnosis section.
Reading History & Scoring
Every probe placement and reading is logged to a reading history you can review after each attempt. Challenges Solved is tracked in My Progress alongside your Safety and Theory scores, and the Troubleshooter badge unlocks once you've resolved every unique fault across all three circuits.
No risk, real reps. Every fault you'll see here is one you'd rather practice on a screen first.