Load switching system and circuit

A load switching circuit, comprising:

• a first supply power terminal and a common terminal;
• a supply power availability detector (a SPA detector) coupled with the first supply power terminal and configured to detect availability of supply power at the first supply power terminal within sixty (60) milliseconds;
• a rail voltage detector with a rail voltage detector input terminal;
• a swell detector with a swell detector input terminal;
• a surge detector with a surge detector input terminal;
• control logic with inputs coupled with the SPA detector, the rail voltage detector, the swell detector, and the surge detector;
• a make timer with an input coupled with the control logic;
• a break timer with an input coupled with the control logic;
• a relay driver with an input coupled with the make timer and an input coupled with the break timer;
• a shunt switch control terminal coupled with the control logic;
• and
• one or more coil control terminals coupled with the relay driver;
• wherein the control logic is configured to:
• cause the relay driver to provide a second coil control output signal on the one or more coil control terminals within three hundred (300) milliseconds after receiving a power-up signal from the SPA detector;
• start the make timer upon receiving a “rail voltage present” signal and wait for a first delay time, then cause the relay driver to provide a first coil control output signal on the one or more coil control terminals;
• start the break timer upon receiving a “swell detected” signal from the swell detector to wait for a second delay time, then cause the relay driver to provide the second coil control output signal on the one or more coil control terminals;
• provide a shunt switch control signal on the shunt switch control terminal upon receiving a “surge detected” signal from the surge detector;
• and
• provide the second coil control output signal on the one or more coil control terminals within ten (10) milliseconds after receiving a “rail fail” signal from the rail voltage detector.