Final answer:
An overvoltage relay is a protective device used to prevent excessive voltage in an electrical system from causing damage to equipment or creating a safety hazard. It operates by isolating the system when a predetermined voltage level is exceeded. These relays are critical for ensuring system safety and reliability.
Step-by-step explanation:
The overvoltage relay is a protective device used in electrical systems to prevent voltage in the system from exceeding a predetermined level. When voltage exceeds this level, it can cause significant damage to electrical equipment and create a safety hazard. The overvoltage relay detects these excessive voltage conditions and operates to isolate the electrical system or equipment by tripping a circuit breaker or opening a switch. This operation helps to protect the system from harm due to overvoltage conditions, such as those caused by surges, faults, or incorrect switching.
Typically, overvoltage relays are set to operate at a voltage level that is above the normal operating range of the system but below the level that would damage equipment. The relay has settings that can be adjusted according to the sensitivity required for the particular application and the characteristics of the electrical system it is protecting.