Breaker Trip Unit Simulator

Electronic trip units give engineers precise control over breaker behavior across four protection functions — Long-Time (overload), Short-Time (sustained fault), Instantaneous (high-level fault), and Ground-Fault — but understanding how LSIG settings interact on a time-current curve is a skill that only comes with hands-on repetition. This simulator puts a live TCC in front of you: adjust Long-Time pickup and delay, Short-Time pickup and delay, Instantaneous pickup, and Ground-Fault pickup and delay, then dial in load or fault current to see exactly where the operating point lands on each region. Frame sizes of 400A, 800A, 1600A, and 3200A anchor the exercise in real-world equipment. Six presets — Normal, Overload, Short Circuit, High Fault, Ground Fault, and Poor Coordination — load common field scenarios in one click. The Trip Curve tab shows the full TCC with current annotation. The Compare tab places two breaker configurations side by side for coordination margin evaluation. The Event Simulator injects current and steps through the trip sequence. The Design Lab (Scenario tab) presents five industry-specific engineering scenarios: Hospital Critical Branch, Data Center Selective Coordination, Warehouse Ground-Fault (GFPE), Manufacturing Line Ride-Through, and Retail Store Basic Protection — each with a defined context and target coordination outcome. The Learn tab covers upstream vs. downstream device roles, the distinction between overload, short-circuit, and ground-fault protection, ground-fault protection for equipment vs. personnel, selective coordination, common LSIG mistakes, and a set of knowledge challenge questions.

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A live look at the app you'll launch — every control on the left drives the visualizations on the right in real time.

• 01Identify the four LSIG regions on a time-current characteristic curve and explain the protection purpose of each
• 02Adjust Long-Time pickup and delay to define the overload response band without encroaching on load inrush or motor-starting curves
• 03Distinguish Short-Time Delay from Instantaneous trip and explain when STD is preferred for selective coordination in downstream breaker pairs
• 04Configure Ground-Fault pickup and delay for equipment protection (GFPE) versus personnel protection and explain the NEC 230.95 threshold
• 05Use the Compare tab to evaluate coordination time interval margin between an upstream main and a downstream branch breaker
• 06Apply one of the five Design Lab scenarios to configure settings for a defined industry context and verify that the TCC meets the scenario's coordination objective

• —Not a design document, stamped calculation, or approval record.
• —Not a substitute for engineering analysis by a licensed professional.
• —Not a relay setting file and not a coordination study of record.
• —Not connected to live equipment and not a safety device.