What defines the continuous rating of a device?

The continuous rating of a device primarily refers to the maximum load the device can handle continuously without overheating or experiencing performance degradation. This rating is crucial because it establishes the safe operating conditions for the device over extended periods, ensuring reliable performance.

In contrast, the other options touch on different aspects of electrical devices. The level of current above which the device begins to react to overcurrent pertains to the protective features of a device, rather than its continuous rating. The maximum short-circuit current speaks to the device's ability to withstand temporary fault conditions, which is not related to its continuous operation. Finally, the minimum operational voltage refers to the lowest voltage at which the device can function but does not define how the device performs under continuous load conditions.

Thus, the correct understanding of the continuous rating revolves around the device's capability to manage sustained loads effectively.