When the load can’t tolerate an interruption, switching between AC sources becomes a core function — not a nice-to-have.
This system monitors three-phase inputs and automatically transfers the output to a secondary source when a failure is detected on the active one. SSRs were chosen for their silent, wear-free operation and precise electronic control over the switching process.
But using SSRs on AC isn’t just swapping a relay for a semiconductor. Voltage rating, thermal dissipation, leakage current, and switching behavior under load all need to be addressed. The STM32L152RET6 handles source and load detection, determines when to switch, enforces the right transfer sequence, and prevents any unsafe overlap between sources.
