What is the minimum output duration needed for a light source used to field test arc-flash detection relays?

The correct answer is 1 ms. In the context of field testing arc-flash detection relays, a very brief duration of light output is essential because the relays are designed to detect instantaneous changes in light intensity caused by an arc flash event. A minimum output duration of 1 ms is sufficient for the detection mechanisms within the relay to register the light signal accurately.

This short duration is crucial because arc flashes occur very rapidly, and the ability of the relay to respond to such an event can significantly impact safety and protection measures in an electrical system. A longer duration may not be as effective because it could introduce delays or noise that might confuse the relay's detection capabilities. Therefore, the requirement of 1 ms ensures that the light signal used for testing reliably triggers the sensor without unnecessary complications.