What is the first step in the procedure to start SIVs when volts drop below 82?

The first step in the procedure to start the SIVs (Static Inverter Vehicles) when the voltage drops below 82 volts is to trip both pantograph MCBs (Miniature Circuit Breakers). This action is necessary because if the voltage level is too low, it can indicate a fault condition or that the electrical supply may not be stable, which can damage the equipment. Tripping the MCBs clears the circuit and helps protect the systems from potential electrical issues.

Once the pantographs are secured, further troubleshooting or corrective actions can be taken to bring the system back to a functional state, ensuring the safety and reliability of the vehicle's electrical systems. Other alternatives, such as raising the local pantograph or resetting the MCBs without first tripping them, do not address the fundamental issue of voltage instability. Pressing the emergency button is reserved for situations requiring immediate action that does not focus on the electrical supply issue at hand.