What is the required response time for backfeed protection upon disconnection of the input AC power source?

The required response time for backfeed protection upon disconnection of the input AC power source is critical in ensuring safety and compliance with electrical standards. A response time of 100 milliseconds is established to ensure that the system disconnects quickly enough to prevent any potential hazards, like electrocution or equipment damage, that could occur in the event of backfeed causing current to flow in unintended ways.

This time frame allows for the swift reaction needed to mitigate risks associated with the loss of the primary power source, especially in marine and other critical environments where equipment must be protected from faults. A shorter response time may not provide sufficient operational reliability under certain conditions, while longer response times could potentially lead to unsafe circumstances.

In the context of the other options, while 50 milliseconds might seem prompt, it may not allow for sufficient system stabilization. On the other hand, response times of 200 milliseconds and 500 milliseconds are considered too slow to ensure the immediate protection required in a disconnection scenario, increasing the risk of backfeed issues occurring. Therefore, a 100 millisecond response time is optimal for balancing safety with operational effectiveness.