What functionality do electro magnetically operated contacts provide in overload relay units?

Electromagnetically operated contacts in overload relay units are primarily designed to trip the circuit when a predetermined current level is exceeded. This functionality is crucial because it protects the connected equipment, such as electric motors, from damage due to overheating or excessive current. When the current exceeds the set limit, the electromagnetic mechanism is activated, causing the contacts to open and disconnect power to the motor. This automatic response helps prevent potential failures, ensures operational safety, and reduces the risk of fire hazards.

The focus on tripping at a specific current level reflects the essential role that overload relays play in electrical systems, serving as a protective measure tailored to the operational characteristics of the motor or equipment in question. This aspect distinguishes this function from other options, which do not align with the purpose of overload relay units within electrical systems.