Industrial Motor Protection with IoT Alerts

Three-phase induction motors are industry's workhorses — pumps, conveyors, compressors, machine tools — and when one fails, the line stops. Most such failures are not random: sustained overload cooks the winding insulation, a lost phase overloads the remaining two, and overheating degrades the motor long before it seizes. A simple fuse or MCB cannot catch any of this properly — fuses are far too slow for single-phasing and blind to gradual thermal damage. Real factories solve it with protection relays that combine inverse-time overload curves, phase-loss detection and thermal sensing. This project recreates that protection panel at demonstration scale: an ESP32 watches per-phase current through ACS712 sensors, body temperature through a DS18B20 probe and phase presence through optocouplers, then trips a 3-pole contactor within seconds of a fault and logs every trip with its cause — the same protection-coordination thinking, in hardware you can actually demo.

1. ACS712 current sensors on each phase feed analog readings to the ESP32, which computes RMS current per phase every mains cycle window.
2. Optocoupler circuits monitor each phase's presence; if any phase disappears while the motor is commanded to run, single-phasing is declared.
3. The DS18B20 probe tracks motor body temperature against the thermal limit.
4. The firmware runs the protection logic: inverse-time accumulation for overload, instantaneous comparison for overcurrent, threshold comparison for temperature, and phase-loss voting.
5. On any protection pickup, the ESP32 de-energizes the contactor coil through a relay driver, latches the trip, sounds the buzzer, lights the fault LED and pushes an alert to the dashboard.
6. The dashboard logs the trip with its cause and pre-trip readings; the operator investigates, fixes the issue and presses reset to allow restart.

• Overload protection with an inverse-time (I²t) thermal curve — trips faster on heavier overloads, like a real thermal relay
• Instantaneous overcurrent trip at an adjustable high-set threshold
• Single-phasing / phase-failure detection via optocoupler sensing on each of the three phases
• Motor overheat protection via DS18B20 temperature probe on the motor body
• Automatic contactor trip on any fault — typically removes motor supply within ~2 seconds of fault detection
• Buzzer + fault-specific LED annunciation (overload, overheat, phase loss each get their own indication)
• IoT dashboard with live per-phase current and temperature graphs
• Trip-event log with fault cause, timestamp and pre-trip values for the report
• Manual reset with lockout after a trip — the motor cannot restart until the fault is acknowledged
• Onboard test buttons to simulate overload and phase loss for live demos without real faults

• Fully assembled motor protection panel with simulated-fault test procedure
• Complete firmware source code (Arduino IDE, well-commented, I²t curve documented)
• Circuit diagram and wiring schematic (power + control + sensing)
• Protection settings and testing procedure sheet
• Project report PDF (protection theory, fault types, simulated-fault test procedure with trip timings, conclusion)
• PPT presentation for final review
• Viva Q&A preparation document (relay curves, single-phasing damage, contactor sizing)
• Dashboard setup guide

FAQs

1. Why is motor protection needed — can't a fuse do this? A fuse only responds to gross overcurrent and is far too slow for single-phasing or gradual overheat, which silently destroy motor windings. This panel combines overload (I²t), phase-loss and thermal protection — the three killers of induction motors — and the report explains each with winding-damage diagrams.
2. What happens during single-phasing? The optocouplers monitor each phase; when one disappears, the remaining two phases carry ~1.73× current, overheating the windings in minutes. The panel trips the contactor immediately and annunciates "phase loss" — you can demo this by switching off one phase of the demo supply.
3. How is the overload trip time calculated? The firmware accumulates I²t (current-squared × time), mimicking a thermal overload relay's heating curve — light overloads take minutes, heavy ones trip in seconds. The settings sheet shows the curve math and how to adjust pickup.
4. How do I demo trips safely in my review? The panel has onboard test buttons that simulate overload current and phase loss electronically, so every protection function trips visibly without stressing the demo motor. You see the full sequence: fault → trip → alarm → logged cause.
5. Does it need WiFi to protect the motor? No — all protection logic runs locally on the ESP32 and trips the contactor even with WiFi down. The cloud side only adds graphs, alerts and the trip log.
6. Can this scale to a real industrial motor? Conceptually, yes — swap the ACS712s for CTs and size the contactor to the motor, and the same protection logic applies. The report covers the scaling math, which makes a strong future-scope slide.