A microcontroller-based system designed for household backup power applications. It continuously monitors mains voltage and automatically controls a generator during power outages. The system integrates an automatic transfer switch (ATS) mechanism to ensure a seamless transfer of the electrical load between mains and generator power.
Power outages can disrupt household operations and damage sensitive equipment. Hades provides an automated solution that:
- Detects power failures.
- Initiates a generator start sequence.
- Transfers load safely to generator output.
- Returns to mains power when available.
The system is built using discrete components and a microcontroller (Arduino), prioritizing reliability and electrical isolation.
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Mains and Generator Voltage Monitoring
Step-down transformers with filtering provide accurate voltage readings and galvanic isolation. -
Automatic Generator Start/Stop
Includes a controlled cranking sequence and shutdown logic. -
Oil Level Protection
Continuously checks the oil level to prevent generator damage. -
Automatic Load Transfer (ATS)
Controls solid-state relays (SSR) to transfer Line and Neutral connections between mains and generator. -
Self-Power Management
Powered from the generator's 12V battery with a 5V regulator. Includes a hold relay to power down the MCU when mains power is restored.
- Monitor mains voltage continuously.
- When voltage falls below the configured threshold:
- Initiate generator cranking.
- Wait until generator voltage stabilizes (215–240V).
- Transfer the load from mains to generator using SSRs and the ATS.
- When mains power is restored:
- Transfer load back to mains.
- Shut down the generator and power down the MCU.
| Pin | Signal Name | Description |
|---|---|---|
| D9 | DO_Generator_Crank_P9_K1 |
Crank relay (initiates generator start) |
| D8 | DO_Generator_Start_P8_K2 |
Start relay (maintains generator run) |
| D7 | DO_OilLamp_Indicator_P7_K3 |
Oil level warning lamp |
| D6 | DO_ArdSup_HoldContact_P6_K4 |
MCU hold relay (self-power management) |
| D5 | DO_GeneratorLine1_Contact_P5_K5 |
Generator Line 1 output relay |
| D4 | DO_GeneratorLine2_Contact_P4_K6 |
Generator Line 2 output relay |
| D3* | DO_MainsLine1_Contact_P3_K7 |
Mains Line 1 output relay (not used) |
| D2* | DO_MainsLine2_Contact_P2_K8 |
Mains Line 2 output relay (not used) |
*Currently commented out in the code.
| Pin | Signal Name | Description |
|---|---|---|
| A3 | DI_Oil_LowLevelContact |
Oil low-level switch input |
| Pin | Signal Name | Description |
|---|---|---|
| A0 | AI_Generator_VoltageLevelSensor_PA0 |
Generator voltage measurement (isolated) |
| A1 | AI_Mains_VoltageLevelSensor_PA1 |
Mains voltage measurement (isolated) |
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Hardware Preparation
- Connect transformers, SSRs, relays, and sensors based on the pinout table.
- Ensure proper isolation for all mains connections.
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Upload the Firmware
- Open
src/hades.inoin the Arduino IDE. - Select the correct board and COM port.
- Upload the firmware to the microcontroller.
- Open
-
Test and Calibrate
- Verify voltage readings.
- Simulate a mains power loss to confirm generator start and transfer sequence.
- This system operates at mains voltage (220–240V). Incorrect installation or handling can result in serious injury or death.
- Ensure all high-voltage wiring is performed by a qualified electrician.
- Improper generator handling (especially during cranking) can damage the generator or cause personal injury.
- Add configurable thresholds via user interface.
- Support for three-phase systems.
- Integrated logging and diagnostic features.