Make control circuits click.
Practice Boolean logic, relay memory, level-control sequencing, and voltage-drop reasoning in a hands-on industrial electrical lab. Change inputs. Observe outputs. Understand why.
Original training material. This lab teaches general electrical principles using newly written examples and diagrams. It does not reproduce, endorse, or include any textbook pages. Virtual demonstration only — no instructions for working on energized equipment.
Flip the inputs. Follow the output.
Series contacts implement AND logic; parallel contacts implement OR logic. Normally closed contacts invert an input. Try all five functions and compare the truth table.
Logic engine
LIVE SIMULATIONBoth inputs must be ON to energize the load.
Current path
LOAD OFFTRUTH TABLE (1 = input active)
| A | B | Output |
|---|
Why does a motor stay on?
A three-wire starter has a momentary START button, a normally closed STOP, an M1 auxiliary seal-in contact, and an overload contact. See what happens after you release START.
Starter panel
M1 DE-ENERGIZEDSTART closes briefly. When the coil energizes, its NO auxiliary contact closes in parallel and holds M1 on.
Three-wire memory principle
ORIGINAL SCHEMATICNC
NO
NO
NC
A normally open auxiliary contact follows the energized state of the coil. Overload protection remains in series.
Build a smarter pump sequence.
Use a lower start threshold and an upper stop threshold to prevent rapid cycling. Experiment with HAND / OFF / AUTO and observe a maintained run command.
Water system simulator
PUMP OFFCycle: pump adds 12%, demand drains 4%. When off, demand drains 4%.
State explanation
HYSTERESISBelow 25% starts the pump. Between the thresholds, the run contact holds. At 80%, the pump stops.
The control mode selects the command. The overload contact should protect every mode, including HAND. This is an educational model, not a certified pump control design.
Measure the difference.
Learn the expected voltage drop across a control contact without touching a live circuit. Simulated source: 115 V AC; load and return path assumed intact.
Virtual multimeter
SIMULATED / NO LIVE POWERWith the contact open and a complete load-to-L2 return path, the supply appears across the open contact.
Fault-finding rule
115 VAC SOURCESafety: voltage-drop measurements on energized equipment require qualified personnel, approved procedures, appropriate test instruments, and electrical safety controls. This lab is conceptual only.
Test what you've learned.
12 original scenario-based questions. Your answers stay in this browser and are not transmitted or stored on our servers.
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Review. Flip. Remember.
Thirty independently written flashcards, plus a Quizlet-compatible import file for your own Quizlet account.
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Practice the logic. Keep human control.
Built for electrical apprentices, maintenance technicians, and curious problem solvers. Our next labs can cover relays, VFDs, PLC inputs, and troubleshooting sequences.