What is the primary purpose of a thermal overload relay?

The primary purpose of a thermal overload relay is to prevent excessive current. This device is specifically designed to monitor the current flowing through a motor or electrical circuit. When the current exceeds a predetermined level for a certain period, the thermal overload relay operates and opens the circuit, thus protecting the connected equipment from overheating and potential damage.

This protective mechanism is crucial as excessive current can lead to the overheating of electrical components, which may result in failures or hazardous situations, such as electrical fires. The relay utilizes thermal sensors or bimetallic elements that respond to heat generated by current flow, ensuring the circuit is interrupted before any harmful damage occurs.

While other choices might touch on concepts relevant to electrical systems, they do not accurately describe the specific function of a thermal overload relay. For example, increasing voltage or improving efficiency involves different components and functions entirely, and using an overload relay does not inherently enhance performance in the sense described by the other options.