System Protect is a 5-minute delay prior to calling for heating or cooling to protect the system from short cycling. It is only applied if the thermostat has detected an unexpected relay state internal to the thermostat during a call.
From ADC: “System Protect is intended to cover rare cases of power issues with the HVAC system. If System Protect is being seen frequently or appears on every call for heat or cool, it points to poor HVAC performance or pre-existing incompatibility. Frequent or extreme System Protect delays can be resolved by installing an isolation relay.”
You’ll need to install an isolation relay in this case. The T3000 terminals are digital relays rather than mechanical, and are very sensitive to excess current draw.
A similar thread is found here detailing this issue and how to resolve.