What does the built-in circuitry of an electronic overload relay sense?

The correct answer focuses on how electronic overload relays function in motor protection. Specifically, they are designed to monitor the current flowing through the motor as well as the temperature, which can indicate overheating conditions.

The built-in circuitry of an electronic overload relay continuously assesses the current levels to detect any deviations from normal operational parameters. When the current increases beyond a predetermined threshold—often indicative of an overloaded condition—the relay responds to prevent potential damage to the motor. Additionally, the relay often incorporates temperature sensing to provide a dual method of protection; high current draw can lead to excessive heating, which the temperature sensing element can detect and react to by trip the circuit.

This ability to sense both current changes and temperature makes electronic overload relays highly effective for safeguarding motors against overheating and excessive current, ensuring reliable operation and longevity of the equipment. Other options, while they might relate to different scenarios in electrical applications, do not accurately reflect the specific capabilities of an electronic overload relay.