Contactors are rated according to which of the following criteria?

Contactors are primarily rated based on the maximum amperage that can safely pass through their contacts without causing damage or failure. This rating is crucial because it ensures that the contactor can handle the electrical load required for the application it is used in, preventing overheating or potential circuit failure.

If a contactor is subjected to current levels that exceed its rated amperage, it may overheat, leading to welds forming on the contacts or eventual failure, which can pose safety risks. This amperage rating also takes into consideration the duty cycle, which refers to the amount of time the contactor is expected to operate under specific conditions.

While voltage across terminals is an important aspect of selecting a contactor, it doesn't fully define the capacity of the device as the amperage rating does. Similarly, frequency of operation impacts the contactor's functionality and lifespan, but it isn't the primary rating attribute. Size and weight of the device might be of concern for physical installation, but they do not directly correlate to the electrical capacity and operational safety of the contactor itself. Thus, maximum amperage through the contacts serves as the key standard for rating contactors.