What function does a protection relay typically serve?

A protection relay primarily serves the function of monitoring electrical current within a motor or electrical system. Its main role is to detect abnormal conditions, such as overloads, short circuits, or other electrical faults that could lead to damage or failure of the motor. When it identifies a fault condition based on preset thresholds, the protection relay takes action to disconnect the motor from the power supply, thereby preventing potential damage and ensuring safe operation.

The monitoring function is crucial because it allows for real-time assessment of the electrical parameters, facilitating quick responses to potential issues. This protective mechanism is essential for maintaining the longevity and reliability of motors and electrical equipment in various applications.

Other options like regulating motor speed or providing a power supply pertain to different functionalities not typically associated with the role of protection relays, which focus specifically on safeguarding against faults rather than controlling operational parameters or supplying power.