About

We’re installing a standby generator on a property that already has a grid-connected solar system. To stop the solar system from back-feeding into the generator during a power outage, we need a 3-phase monitoring and control circuit designed. The system should disconnect the solar inverters when mains power is lost, and only reconnect them manually once grid power is restored and stable. How It Should Work Normal Operation - Mains power is healthy on all 3 phases. - The phase-failure relay is energized and keeps the solar inverter contactor closed (solar connected to grid). Power Failure / Phase Loss - If any phase is lost or voltage drops too low, the phase-failure relay de-energizes. - This opens the solar contactor, isolating the inverters. Generator Starts - After ~30 seconds, the generator automatically starts. - The solar remains disconnected so it doesn’t feed power into the generator. Mains Power Returns - The ATS (Automatic Transfer Switch) switches load back to the mains. - The solar system stays isolated until it’s manually reset. Manual Reset - The customer confirms mains power is stable. -They press a momentary push button to reset the system. - The reset energizes a latching relay and reactivates the solar contactor. - Solar inverters reconnect to the grid. We’re looking for an engineer to: - Design a schematic diagram showing: - 3-phase monitor relay (phase failure / undervoltage) - Contactor and latch relay logic - Manual reset push button and indicator - Provide a parts list (BOM) with model numbers - Include a short functional description Parts Can Be Sourced From You can choose components from any of the following: - RS Components (RS Online): https://au.rs-online.com - Door Electric: https://www.doreelectrics.com.au/ - Tradezone: https://www.tradezone.com.au