Which device is responsible for monitoring electrical parameters in a system?

The protective relay is essential for monitoring electrical parameters in a system, as it continuously observes the electrical characteristics such as voltage, current, frequency, and phase balance. Its primary function is to detect abnormal conditions that may indicate faults, such as overloads or short circuits. Upon identifying such issues, the relay can initiate actions to protect electrical equipment and ensure system stability, often by sending signals to circuit breakers to disconnect affected components.

In contrast, transformers are designed to alter voltage levels and do not typically monitor system parameters. Contactors serve the role of switching electrical circuits on and off but lack monitoring functions. Switchgear does play a role in controlling and protecting electrical equipment but is not primarily dedicated to the real-time monitoring of electrical parameters as the protective relay is. Thus, the role of monitoring specifically aligns with the functions of a protective relay.