Relay and Industrial Load Control
Control a low-voltage simulated load with isolation, interlocks and fail-safe output logic.
Learning objective
Control a low-voltage simulated load with isolation, interlocks and fail-safe output logic.
Components and tools
- Development board
- Current-limited low-voltage supply
- Digital multimeter
- Oscilloscope or logic analyser
- Emergency power disconnect
Safety before motion
- Students must not wire mains or high-energy industrial loads.nA qualified person must design actual isolation, protection and enclosure.nUse hardware interlocks for hazardous motion.
Practical procedure
- Use only a 12/24 V isolated training load.nVerify relay coil/input rating.nImplement power-up OFF state.nTest manual stop and feedback/interlock.nSimulate welded-contact or missing-feedback fault.
Measurement checkpoints
| Checkpoint | Expected | Instrument | Safety limit |
|---|---|---|---|
| Power-up | Output remains OFF | DMM/indicator | Fail-safenInterlock |
Troubleshooting
| Symptom | Check | Corrective action |
|---|---|---|
| Relay chatters | Supply/drive insufficient | Correct driver/flybacknOutput unsafe at boot |
Engineering sizing tools
Calculate before powering
Mandatory pre-start gate
Machine safety checklist
The simulated enable button remains locked until every item is confirmed.